## Craig Loehle Reconstruction

Thread for discussion of Loehle 2007. I’ll try to comment later but have some other obligations right now.

Craig Loehle sneds the following information on provenance:
1) GRIP borehole temperature (Dahl-Jensen et al., 1998): See Moberg Nature site supplementary material [SM – digitized version is at http://data.climateaudit.org/data/moberg/djgrip.dat )
2) Conroy Lake pollen (Gajewski, 1988): ftp://ftp.ncdc.noaa.gov/pub/data/paleo/pollen/recons/liadata.txt
3) Chesapeake Bay Mg/Ca (Cronin et al., 2003): ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2003/ [SM question: two T series – which column?]
4) Sargasso Sea 18O (Keigwin, 1996); ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/keigwin1996/
5) Caribbean Sea 18O (Nyberg et al., 2002); ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/nyberg2002/ CL: converted to temperature on the Moberg article nature site suppl material. SM – which version is used in Moberg (and Loehle?)
6) Lake Tsuolbmajavri diatoms (Korhola et al., 2000); See Moberg Nature site supplementary material. Digitized version from print version at http://data.climateaudit.org/data/moberg/lauritzen_fig11_points
7) Shihua Cave layer thickness (Tan et al., 2003); ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/china/shihua_tan2003.txt use col 7 temp
8.) China composite (Yang et al., 2002) CL – this does use tree ring width for two out of the eight series that are averaged to get the composite, or 1.4% of the total data input to the mean computed below; ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yang2002/china_temp.txt SM- which version?
9) speleothem data from a South African cave (Holmgren et al., 1999); CL: from authoremail sent for archive link SM: compare to ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/africa/cold_air_cave.txt
10) SST variations (warm season) off West Africa (deMenocal et al., 2000); ODP_658C ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/demenocal2000/
11) SST from the southeast Atlantic (Farmer et al., 2005);ODP_1084B ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/farmer2005/
12) SST reconstruction in the Norwegian Sea (Calvo et al., 2002) – MD952011 SM: perhaps box core JM97-948/2A (CL link incorrect: compare to http://doi.pangaea.de/10.1594/PANGAEA.438810?format=html http://doi.pangaea.de/10.1594/PANGAEA.510801?format=html
13-14) SST from two cores in the western tropical Pacific (Stott et al., 2004); MD98_2181 MD98_2176
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/stott2004/
15) mean temperature for North America based on pollen profiles (Viau et al.,2006);
http://www.lpc.uottawa.ca/data/reconstructions/index.html
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/pollen/recons/northamerica/viau2006namerica-temp.txt
16) a phenology-based reconstruction from China (Ge et al., 2003);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/historical/china/china_winter_temp.txt
17) annual mean SST for northern Pacific site SSDP-102 (Latitude 34.9530, Longitude 128.8810) from Kim et al. (2004);
http://doi.pangaea.de/10.1594/PANGAEA.438838
18) Spannagel Cave (Central Alps) stalagmite oxygen isotope data (Mangini et al., 2005).
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/europe/austria/spannagel2005.txtmean SST for northern Pacific site

Script (RichardT) for site map:

ibrary(maps)map()
pos=list(GRIP=c(73, -38),Conroy=c(46, -68),Chesapeake=c(38, -76),Sargasso=c(33, -57), Caribbean=c(18, -67), Tsuolbmajavri=c(68, 22), Shihua=c(40,116),Cold_Air_Cave=c(-24, 29.2),ODP_658C=c(20.75, -18.58),ODP_1084B=c(-25.5, 13),MD952011=c(66.967,7.633),MD98_2181=c(6.3, 125.83),MD98_2176=c(-5, 133.44),SSDP_102=c(34.9530, 128.8810), Spannagel=c(47.0882, 11.6715))
pos2=t(sapply(pos,function(p)p))
points(pos2[,2],pos2[,1], col=2, pch=16)
text(pos2[,2],pos2[,1], col=2, label=rownames(pos2), pos=c(2,2,2,2,2,4,2,4,2,2,2,2,2,2,2), cex=.7)

1. Craig Loehle
Posted Nov 15, 2007 at 12:46 PM | Permalink

What happens if you do a climate reconstruction without using tree rings? You don’t have as much data, but the result is:
Loehle, C. 2007. A 2000-year global temperature reconstruction based on non-treering proxies. Energy & Environment 18(7-8): 1049-1058.
Abstract:
Historical data provide a baseline for judging how anomalous recent temperature changes are and for assessing the degree to which organisms are likely to be adversely affected by current or future warming. Climate histories are commonly reconstructed from a variety of sources, including ice cores, tree rings, and sediment. Tree-ring data, being the most abundant for recent centuries, tend to dominate reconstructions. There are reasons to believe that tree ring data may not properly capture long-term climate changes. In this study, eighteen 2000-year-long series were obtained that were not based on tree ring data. Data in each series were smoothed with a 30-year running mean. All data were then converted to anomalies by subtracting the mean of each series from that series. The overall mean series was then computed by simple averaging. The mean time series shows quite coherent structure. The mean series shows the Medieval Warm Period (MWP) and Little Ice Age (LIA) quite clearly, with the MWP being approximately 0.3°C warmer than 20th century values at these eighteen sites.
available at:
http://www.ncasi.org/publications/Detail.aspx?id=3025

2. Pat Keating
Posted Nov 15, 2007 at 1:29 PM | Permalink

565
WOW! Thanks for the great post, Craig, and congratulations on putting together a much-need temperature reconstruction. That is big.
What does RealClimate say?

3. Posted Nov 15, 2007 at 1:35 PM | Permalink

# 564

Steven Mosher, Thank you!

# 565

Craig Loehle,

Very interesting and well documented paper! I have a suggestion; make the x axis crosses at the minimum value so the legends of time series are readable. BTW, I also used Moeberg data for the reconstruction of anomalies of temperature from 700 AD to date.

4. jae
Posted Nov 15, 2007 at 1:37 PM | Permalink

Craig: GREAT, I’ve been waiting, as you know. Congrats.

5. steven mosher
Posted Nov 15, 2007 at 1:51 PM | Permalink

RE 565. Congratulations craig.

I say you need to run the GAUNTLET here at CA and have people throw tomatoes at your paper.
I cannot imagine anything more exhilerating than having the CA crowd throw tomatoes at my work.

I’ve downloaded yours. Sad to say my tomatoes are small but I’ll throw what I have when I get a chance.

6. Craig Loehle
Posted Nov 15, 2007 at 2:58 PM | Permalink

Re: Steven Mosher throwing tomatoes at my reconstruction (see toward end of Unthreaded #24): Thanks to CA I was warned about certain data sets, and warned also about the variety of tomatoes that can be thrown, so I’m not too worried about that. I can imagine that RC will turn up their noses at the proxies I used, since they are addicted to bristlecones and I didn’t use any fancy stats. By the way, GRL sent it back unreviewed because they were tired of seeing reconstructions.

7. tpguydk
Posted Nov 15, 2007 at 3:58 PM | Permalink

you’re right Craig, they’ll ignore it. Going to read it now. Congrats on getting something that bucks the consensus published; it’s about time.

Posted Nov 15, 2007 at 4:15 PM | Permalink

From Craig’s paper

Many other series could not be used because they had too few dates within the 2000-year span or were not calibrated to temperature. In a few cases, data that were appropriate could not be obtained from authors.

Just wondering, who wouldn’t give up their data?

9. Posted Nov 15, 2007 at 4:49 PM | Permalink

Craig Loehle:
I am not a statistician, but I see a major problem with your method of subtracting each series’ mean from the series data points. Assuming that the late 20th century is warmer than earlier periods, a short series that ends in the late 20th century will be artificially cooled. (Similarly, a short series centred on the MWP would be artifically cooled, but you are unlikely to have any series centred on that time frame).

To illustrate, pretend that we have the following average temperatures (completely made up, but showing MWP roughly equal to present day):
1950-2000: 1.0
1800-1950: 0.5
1100-1800: 0.0
1000-1100: 1.0

And we have the following perfect proxy series:
Series A: 1800-2000
Series B: 1000-2000

Series A has an average of 0.3125. Series B has an average of 0.225. So, after shifting, we get:
1950-2000: A=+0.375, B=+0.775, Avg=+0.575
1800-1950: A=-0.125, B=+0.275, Avg=+0.075
1100-1800: A=(none), B=-0.225, Avg=-0.225
1000-1100: A=(none), B=+0.775, Avg=+0.775

So, even though the imaginary temperatures were the same from 1000-1100 as 1950-2000, the reconstruction using your method shows 1000-1100 to be warmer by +0.2.

I am also curious why your plots seem to end around 1970 instead of 2000.

10. Posted Nov 15, 2007 at 4:50 PM | Permalink

Typo above: Series A has an average of 0.625 (not 0.3125).

11. Posted Nov 15, 2007 at 4:51 PM | Permalink

One more question:
Could we see the individual proxy temperatures before combining? If many of them show a warmer MWP, that would be a very strong case for your argument.

12. reid simpson
Posted Nov 15, 2007 at 5:56 PM | Permalink

JohnV:

Not sure I understand your point and do not want to answer for Craig, but the abstract states: “In this study, eighteen 2000-year-long series were obtained that were not based on tree ring data.” Since each of the series was 2000 years long, doesn’t this allay your concerns?

13. Posted Nov 15, 2007 at 6:09 PM | Permalink

reid simpson:
Ah yes, I see that in the Abstract now. I was reading the body of the paper, where the lengths of the series were not clear (or I missed them). I will have to think about the effect of subtracting the mean from trends with different shapes. I know that I rejected that approach for OpenTemp because it had some issues — I just can’t remember exactly what they are.

Elsewhere the paper states “This was done instead of using a standardization date such as 1970 because series date intervals did not all line up or all extend to the same ending date.“. I am not sure how to reconcile that with “eighteen 2000-year-long series” from the abstract.

Hopefully Craig Loehle can provide the series data. The current archive seems to include only the eighteen-series mean.

14. scp
Posted Nov 15, 2007 at 6:44 PM | Permalink

Well, I think RC will say “It’s Energy & Environment don’t you know.
No need to take that seriously”. Then, they’ll run for the ice. ; -)

15. pk
Posted Nov 15, 2007 at 6:57 PM | Permalink

Well, I think RC will say Its Energy & Environment dont you know.
No need to take that seriously. Then, theyll run for the ice. ; -)

What ice?

16. bender
Posted Nov 15, 2007 at 7:07 PM | Permalink

My review:

I would accept this paper for publication subject to major revision.

The writing style is clear and concise, and the introduction is useful, especially the summary of the problem with tree ring based based proxies. For that reason the approach is novel and the results worthy of publication.

There are several problems with the paper as submitted, but none of them are fatal.

(1) The locations of the proxies are not mapped. The audience needs to know two things: (i) what’s the largest area not covered by the network; (ii) what’s the average distance between sample points. i.e. What is the extent & resolution of the proxy network.
(2) The locations of the proxies that could not be obtained are not mapped. Consequently there is now way to evaluate the potential spatial importance of these missing data.
(3) There is no indication as to how spatially variable the proxies are in their degree of coherence to the global mean. Readers will want to see a global map of the correlation field.
(4) The individual proxy series should absolutely not be smoothed prior to the analysis of among-proxy variability. Through the Slutsky effect, this has the effect of exaggerating mid-frequency coherence, and attenuating between-proxy variability. The proxies are likely not as reliable as the analysis supposes. Although the attempt to quantify this variability is laudable.
(5) Although a permutation approach to sensitivity analysis is acceptable, there are boostrap methods available for robust significance testing. Generelized cross-validation should also be explored. Uncertainty analysis is one of the most critical areas of proxy-based temperature reconstruction and this paper has an opportunity to make a very useful contribution in this area. Exploration here will boost the value of the paper and attract the interest of a wider audience.
(6) The author should consider plotting 95% confidence intervals on the mean chronology, although it is recognized that there is error in both the x (date) and y (proxy value) co-ordinates, making this task more difficult than with accurately-dated tree-ring based proxies.
(7) Limitations in the proxies used should be discussed more fully. e.g. In the same level of depth that the tree-ring based reconstrucitons are discussed in the introduction.
(8) Individual proxies should be archived and the analysis script made available to verify correctness.

The author should address each of these concerns in a rebuttal or make the necessary changes. I would leave it to the Editor to determine if re-review is required. I would be pleased to serve in that role if called upon.

17. Posted Nov 15, 2007 at 7:09 PM | Permalink

Re #13:
If the series are all 2000 years long, then subtracting their mean will have no effect on the combined shape. That is, my concerns from above are unfounded if all series are 2000 years long.

So, are they all the same length?

18. bender
Posted Nov 15, 2007 at 7:10 PM | Permalink

Attacking EE is ad hom. Well done, Dr. Loehle.

19. steven mosher
Posted Nov 15, 2007 at 7:12 PM | Permalink

CA regulars, Craig deserves your best criticism.

You all know what people will say about E&E. THAT critique does NOTHING to help craig
refine his case and add something to our knowledge bucket.

So, Give craig a worser beating than Pennstate Mann’s “peer review” gave him.

There are worse things than being wrong.

20. Timo Viitanen
Posted Nov 15, 2007 at 7:22 PM | Permalink

#9

It looks like all the series are clamped to the same time frame, 2000 years ago to now, so that shouldn’t be a problem?

21. Timo Viitanen
Posted Nov 15, 2007 at 7:25 PM | Permalink

Sorry, didn’t hit “refresh” often enough :p

22. JS
Posted Nov 15, 2007 at 7:32 PM | Permalink

How does the computed mean compare with, say, the first few principal component?

Think of it as just another robustness test.

The implicit hypothesis behind the averaging of the data is that each series contains a signal plus some noise that cancels out in the averaging. Principal components analysis just takes that process a little further by presuming a signal plus other components that can be common or idosyncratic. If you use PCA to find the common components (not necessarily confined to one particular principal component) its just a slightly different way of cancelling out the idosyncratic noise than averaging. You would probably want to check the loadings of the series into the principal components to make a determinantion about common or idiosyncratic.

23. bender
Posted Nov 15, 2007 at 7:34 PM | Permalink

#21
Agreed. I had intended to submit my review at CA even before your admonition to do so. I formulated it in my head over coffee break but it took a few hours to get home to type it in.

24. bender
Posted Nov 15, 2007 at 7:36 PM | Permalink

Re #24
Usually the first PC in PCA IS the mean vector.

25. JS
Posted Nov 15, 2007 at 7:51 PM | Permalink

#26

Really?!

That isn’t obvious to me and I’d be surprised if it was a general result. But I’m happy to be surprised…

(I can think of restrictions that might make it true, but those restrictions kind of presuppose the answer, which defeats the need for PCA.)

26. bender
Posted Nov 15, 2007 at 7:57 PM | Permalink

I don’t know under what condiitons it is true or not – just that it happens a lot of the time with the data I use. Steve M is an algebra-nut though. He might know.

27. Steve McIntyre
Posted Nov 15, 2007 at 8:07 PM | Permalink

PCA has the disadvantage of not caring about the sign – which is “throwing” away relevant information if you think that you know the orientation of theproxy – which you should. I’d encourage people to think about linear mixed effects as a method if you think that there is a “signal” where the “noise” can vary. Easier to say than to do, tho.

28. bender
Posted Nov 15, 2007 at 8:17 PM | Permalink

When I said PC1 is usually the mean, I should have said ‘absolute value of the mean’. The issue here is not the sign of PC1, but its loadings. i.e. its shape.

29. bender
Posted Nov 15, 2007 at 8:21 PM | Permalink

Maybe it’s because I do not work with non-stationary input vectors? The HS of bcps is highly non-stationary, and this may be what promotes the blade up to PC1 despite it not being the mean vector? Just guessing.

30. Allencic
Posted Nov 15, 2007 at 8:23 PM | Permalink

#19
Yes, there are things worse than being wrong. You could be Al Gore, which means being not only wrong, but scientifically and mathematically dumb too.

31. Kristen Byrnes
Posted Nov 15, 2007 at 8:42 PM | Permalink

I agree with John V. in that the graph ends in the 70’s. I think the reconstruction is pretty good because I can see all of the solar events I would expect to see, but only up until about 1975.

32. steven mosher
Posted Nov 15, 2007 at 8:55 PM | Permalink

Craig,

the approach of selecting non “tree ring series” is methodologically interesting.

I’m interested in your selection criteria after that. The total list of non tree ring
stuff, why did you picked 2000 years?

Throwing out tree rings can also be a subtle form of cherry picking.

More to follow.

33. Steve Moore
Posted Nov 15, 2007 at 9:27 PM | Permalink

A nit to pick with #5:

I say you need to run the GAUNTLET…

One runs a GANTLET (a form of punishment in which a person is forced to run between two lines of men facing each other and armed with clubs or whips to beat the victim).

One wears or throws a GAUNTLET (a glove worn with medieval armor to protect the hand).

34. Bernie
Posted Nov 15, 2007 at 9:42 PM | Permalink

This is a compelling article. However, the general tone here is on target, in that those committed to tree rings and HS will be fierce in how they pull this apart. I suspect it is already being dissected and torn apart.
Has the raw proxy data been archived? Can Craig’s work be replicated?

35. steven mosher
Posted Nov 15, 2007 at 9:44 PM | Permalink

Re 33. I like having my nits picked. Kinda primal.

36. Geoff Sherrington
Posted Nov 15, 2007 at 9:49 PM | Permalink

Re # 32 Steven Mosher,

Are you not being a little unkind in saying that throwing out tree rings can be a form of cherry picking? I thought the logic behind the paper went that there was doubt about the utility of tree rings, so let’s see what other proxies look like without tree rings. I can also pick at points after a first reading of the paper, but to me the important factor was that the signal:noise ratio looks favourable. Sure there can be better description of noise, and we might be treated to more such data.

My main philosophical problem is that some arguments used to doubt tree ring thermometry can often be levelled at the remaining methods. While it is encouraging to see other methods marching in step, one wonders if part of this is due to a dominant effect, such as the scientific truth of oxygen isotope work upon which a lot of reliance is placed. But not all, which is good.

Bender #16 has written a short thesis of his own which covers other comments I could volunteer. But overall, Dr Loehle has done good work to answer a question that many of us must have asked. Take away tree rings, then what do you find?

37. Bob Koss
Posted Nov 15, 2007 at 10:40 PM | Permalink

A nit to pick with #33: 🙂

One runs a GANTLET (a form of punishment in which a person is forced to run between two lines of men facing each other and armed with clubs or whips to beat the victim).

One wears or throws a GAUNTLET (a glove worn with medieval armor to protect the hand).

Not being familiar with the spelling you used, I checked with my friend Merriam.
He seems to think GANTLET is a variant of GAUNTLET. Webster

38. Steve Moore
Posted Nov 15, 2007 at 10:54 PM | Permalink

Bob in #37:

Webster gives the variant spelling, but I used the definitions I was taught — which I still believe to be the primary ones.

The King’s English just ain’t what it used to be:
Perimeter/parameter, compose/comprise, gantlet/gauntlet, etc…

39. Posted Nov 15, 2007 at 11:09 PM | Permalink

A Nit to pick with # 5, # 33, # 37, etc…

Stop this senseless discusion, Gantlet is “…a section of double railroad tracks formed by the temporary convergence of two parallel tracks in such a way that each set remains independent while traversing the same ground, affording passage at a narrow place without need of switching.”

Taken from The Free Dictionary 😉

40. tetris
Posted Nov 15, 2007 at 11:31 PM | Permalink

Re: 16 and 36
Bender and Geoff Sherrington
Gauntlets, tomatoes and other trivia aside, it would seem to me that it might be a tad more useful all around to focus on Bender’s detailed comments in 16 and Geoff’s pertinent question in 36 [“take away tree rings, then what do you find”?]

41. Jonde
Posted Nov 15, 2007 at 11:46 PM | Permalink

Because of limited data in the 20th century and the fact that the reconstruction is only done until late 1970’s, I would suggest that Dr. Loehle would only focus on pointing the globe wide phenomenons of MWP and LIA. Last paragraph of the paper in page 7 “One persistent question…” should be committed because of lack of sufficient data to back up this conclusion. This way the paper would leave much less room for AGW hand waving. Focus on only to the point you can clearly prove and leave speculation to minimum.

42. DeWitt Payne
Posted Nov 16, 2007 at 12:16 AM | Permalink

I would be interested in seeing a frequency domain analysis of the series.

43. Posted Nov 16, 2007 at 12:23 AM | Permalink

Ok, Tetris.

# 16

Bender,

I would agree with you on points 1-3 if Dr. Loehle wouldn’t include references to his work. The references fill in the hole you referred to on his paper.

I agree with you on point 4, although it has not serious statistical consequences upon the analysis of Dr. Loehle’s paper.

I don’t understand your point 5. Would you be so kind as to expand yourself on that point?

I disagree on your point 6. Proxies based on carbonates, pollen, sediments, diatoms, foraminifera, oxygen isotopes in clam shells, iron stains, etc., are more accurate than tree rings proxies. If it was not thus, then our wristwatches were based on pines logs… 🙂

I agree with you on point 7.

What you ask for in your point 8 would be useful if Dr. Loehle was a thesis. It’s not.

# 36

Geoff Sherrington,

As I told Bender, proxies from carbonates, pollen, sediments, diatoms, foraminifera, oxygen isotopes in clam shells, iron stains, etc. are more consistent than tree-rings alternate method. One of the advantages of data completed from alternate methods is their abundance, their stability, their dispersion on the planet, their accessibility, etc. Tree rings proxies might be useful at high latitudes only and require special attention to confounding factors.

44. Posted Nov 16, 2007 at 12:30 AM | Permalink

# 41

Jonde,

I would suggest that Dr. Loehle would only focus on pointing the globe wide phenomenons of MWP and LIA.

You’re right, but first I would demonstrate that MWP and LIA were real.

Focus on only to the point you can clearly prove and leave speculation to minimum.

Yeah, you’re right.

45. joshua corning
Posted Nov 16, 2007 at 12:31 AM | Permalink

The Kings English just aint what it used to be:

Technically isn’t the King’s English French?

46. Posted Nov 16, 2007 at 1:21 AM | Permalink

I’ll just copy Bender’s (4), (6), (8), and add

To date, only two long-term reconstructions have been published (low-frequency series of Moberg et al., 2005; Viau et al., 2006) that do not incorporate tree ring data.

Note http://www.ncdc.noaa.gov/paleo/ei/ei_nodendro.html (not very long-term).

I’d avoid repetition of word ‘believe’ in this kind of publications. Extra points for not using term ‘remarkably similar’.

OT-ish, if proxy response has a limited bandwidth wrt. target, the commonly used model P=scale*T+noise won’t work well.

47. Posted Nov 16, 2007 at 1:23 AM | Permalink

John V in #9 has got it right (and he is not even a statistician). The author dude does not know anything about censored data, which comes up in survivability analysis among other areas. The real crisis you guys will never touch, oil depletion, has to always deal with a bunch of cornucopians running around talking about abundances of reserve oil growth due to their improper use of censored data. The way around this is to actually come up with a model of what’s happening with the censored data so that you can merge in the sets of data properly. But of course you won’t do this because you are not actually scientists or engineers.

And once again, great idea in ending the data at 1970 … bleh.

A really pathetic paper.

48. Hans Erren
Posted Nov 16, 2007 at 1:49 AM | Permalink

re 13

The series used were:
1) GRIP borehole 18O temperature (Dahl-Jensen et al., 1998);
2) Conroy Lake pollen (Gajewski, 1988);
3) Chesapeake Bay Mg/Ca (Cronin et al., 2003);
4) Sargasso Sea 18O (Keigwin, 1996);
5) Caribbean Sea 18O (Nyberg et al., 2002);
6) Lake Tsuolbmajavri diatoms (Korhola et al., 2000);
7) Shihua Cave layer thickness (Tan et al., 2003);
8) China composite (Yang et al., 2002) which does use tree ring width for two out of the eight series that are averaged to get the composite, or 1.4% of the total data input to the mean computed below;
9) speleothem data from a South African cave (Holmgren et al., 1999);
10) SST variations (warm season) off West Africa (deMenocal et al., 2000);
11) SST from the southeast Atlantic (Farmer et al., 2005);
12) SST reconstruction in the Norwegian Sea (Calvo et al., 2002);
13) SST from two cores in the western tropical Pacific (Stott et al., 2004);
14) mean temperature for North America based on pollen profiles (Viau et al.,2006);
15) a phenology-based reconstruction from China (Ge et al., 2003);
16) annual mean SST for northern Pacific site SSDP-102 (Latitude 34.9530, Longitude 128.8810) from
Kim et al. (2004); and
17) Spannagel Cave (Central Alps) stalagmite oxygen isotope data (Mangini et al., 2005).

This gave a total of eighteen (?) series with quite wide geographic coverage (including tropical) and based on multiple proxies.

49. richardT
Posted Nov 16, 2007 at 2:01 AM | Permalink

#16
In addition to several of your recommendations for revision, my review would add that the manuscript should include a figure comparing the proposed reconstruction with that of previous hemispheric and global reconstructions, and detail what new insights, if any, if offers over Moberg et al.

50. richardT
Posted Nov 16, 2007 at 2:12 AM | Permalink

From the manuscript: “all data were used that had at least 20 dates over the 2000-year period.”
This is simply wrong. Few, if any, of the sediment proxies have 20 dates in the last 2000 years. Sargasso Sea 18O (Keigwin, 1996) certainly does not.

51. MarkR
Posted Nov 16, 2007 at 2:51 AM | Permalink

Craig Loehle. Excellent paper. Good selection of Proxies. Good geographical spread. Straight forward transparent Statistical method. Written in good clear English. Good tests for Robustness to particular Proxies being left out.

Having read a lot of the Hockey Team papers, you put them to shame for your clarity, straight forwardness, succinctness. Thank you so much.

The criticism above that the data ends in 1970 applies to all the multi proxy studies, cos the scientists won’t update their Proxies, or won’t publish if they have updated.

The message is clear. 20th Century Warming is not unprecedented. The MWP was not localised to Northern Europe. Temperature does not rise and fall in concert with CO2. We can now also see the Roman Warm Period, matching ours for temperature.

I would like to see a paper based on the longer series Proxies going back Millennia.

52. Hans Erren
Posted Nov 16, 2007 at 3:41 AM | Permalink

Before I give my verdict, I’d like to see the input data. I remember well Steve Mc’s apple picking exercise to “get” the MWP.
So, links to the archives, anybody?

53. Robinson
Posted Nov 16, 2007 at 3:51 AM | Permalink

Nice work. Am I the only one to question why this hasn’t been looked at before? Surely it occurred to someone to see what happens when you don’t use tree proxies?

54. MarkR
Posted Nov 16, 2007 at 3:56 AM | Permalink

Robinson. The Hockey Team are school bullies who gang up in the Peer Review process to prevent publication if they can. This one slipped through, but they have Nature etc. under lock and key with the co-operation of the Editorial Staff. Be interesting to see how hostile the Peer Review was on this one.

55. MarkR
Posted Nov 16, 2007 at 4:17 AM | Permalink

Swedish Gatlopp

56. Hans Erren
Posted Nov 16, 2007 at 4:28 AM | Permalink

57. Douglas Foss
Posted Nov 16, 2007 at 5:11 AM | Permalink

The clear prose was a breath of fresh air. I cannot comment on the statistics, not having the training. But, at least a couple of aspects of the paper stood out to me.

First, looking at the graphs, the rate of increase of climate temperature over time derived from these proxies appears to be greater over the last 300+ years than leading up to the MWP. As reflected in Figure 2, between c. 1650 to 1995, the anomaly went from -0.6ºC to 0.5ºC, whereas the anomaly moved from roughly -0.4ºC in about 450 A.D. to roughly 0.75ºC about 950 AD. The current warming is not as great in terms of anomaly, but the rate of change since the end of the LIA appears to be about a third larger. Relative rates of change offer fodder for a claim that increased levels of carbon dioxide accelerate the rate of temperature increase. I could not determine from the graphs precisely, but it appeared that the rate of change early in the 18th century was greater than the rate of change in the latter portion of the 20th century. Perhaps Craigs data and methods do not afford a degree of resolution necessary to reach conclusions on these points.

Craigs conclusions conform with alternative proxies not generally mentioned. His Figure 2 graph reflects optimal warmth during the peak of Roman order and influence  the age of the Antonines. The sharp decline in the temperature graph after about 200 A.D. corresponds to increasing disorder in the empire. Temperatures rose thereafter as shown on Figure 2, and by the late 200s, under the Tetrachy of Diocletian and ultimately under Constantine, order was largely restored in the empire. But Craigs data reflects another precipitous drop in temperature beginning about 370 A.D. The empire had largely collapsed by 411 A.D. when Alaric and the Goths sacked the City, but historical reports prior to 376 A.D. reflect pressures upon various Gothic tribes along the eastern reaches of the Danube. Historians believe that as early as the 350s, Huns were pressing westward and southward against the Alans, who in turn pressed into a Gothic tribe known as the Greuthungi. There are accounts of disruptions caused by this influx or peoples along the Don River and north of the Sea of Azov. Ammianus account of events have the Huns pressing into the Alans, the Alans into the Greuthungi, and the Greuthungi into another Gothic tribe known as the Tervingi. We know from Eunapius that 200,000 Tervingi appeared on the banks of the Danube in the spring of 376 petitioning to be admitted across the river and into the Roman Empire, a petition which was granted. It therefore would not be the least surprising that temperatures fell sharply over the decades from 350 A.D. through 410 A.D. and forced wholesale relocation of peoples. Finally, probably known to everyone here, absolute peak warmth on Craig’s graphs coincides with the Vikings raising corn on Greenland. In other words, Craigs data conforms to what I remember of history.

58. kim
Posted Nov 16, 2007 at 5:19 AM | Permalink

Time machine insight, Douglas; thank you.
=========================

59. Rob Wilson
Posted Nov 16, 2007 at 5:22 AM | Permalink

Craig et al,
A few of the comments above have wanted to see some comparison with previous reconstructions.

See figure below (hopefully it can be seen)

Panel A compares the Loehle series with the DArrigo RCS, Esper and Moberg NH reconstruction. All series have been smoothed with a 30 years spline and standardised to the common period. So  they all show a generally similar shape. The large difference in Panel A is in the recent period, where the relative levels of the recent period are quite different between series. This has implications for calibration.

I only skimmed the paper quickly, but cannot remember seeing what method or target you used for calibration. In Panel B, I have scaled (same mean and variance for the period of common overlap – 1850-1979) all the series to NH temperatures (averaged from 0-90 degrees latitude using the CRU3 land/ocean data-set). This is likely not an optimal target for all the data-sets, but it is a compromise for this exercise. Panel C shows the same graph, but for the last 250 years.

The Loehle series clearly shows an elevated MWP compared to the other records with temperatures comparable to the late 20th/early 21st century period.

Now the real question is  how robust is your reconstruction? Without seeing the individual constituent proxy records, it is difficult for a reader to make a site-by-site assessment of MWP vs. present conditions. Also  as #9 notes above, the method you used could introduce bias when comparing MWP and present conditions. As I am sure Steve will tell you, some of your proxies may not be true temperature proxies either.

If your series is robust, it would have major implications for attribution studies. However, by giving up after rejection from GRL and going for E+E, it is quite likely that your series will never be taken seriously.

My 10 pence worth
Rob

60. Robinson
Posted Nov 16, 2007 at 5:24 AM | Permalink

MarkR, maybe I have too much faith in Science. Theories become “fashionable” (string theory for example) but I don’t believe there is a systemic attempt at deception going on in any branch of science. A collective delusion I could understand however. I do believe the truth will win through eventually, whatever that may turn out to be.

61. Jason
Posted Nov 16, 2007 at 6:25 AM | Permalink

There should be no mystery why the data ends early.

The paper explicitly says that each series goes from 1AD to 1995AD and was smoothed with a running mean (producing values from 16AD to 1980AD).

62. Jason
Posted Nov 16, 2007 at 6:31 AM | Permalink

What were the comments from GRL when they rejected this?

63. MattN
Posted Nov 16, 2007 at 6:34 AM | Permalink

My oh my. This is looking to be quite a week. Congrats on the paper Craig.

Any word from Broke Stick Mountain?

64. MattN
Posted Nov 16, 2007 at 6:36 AM | Permalink

I suppose the question has to be asked: Craig, which oil company are you funded by?

😛

65. DocMartyn
Posted Nov 16, 2007 at 6:49 AM | Permalink

Very nice plots. I wonder if you have done the same analysis in the oppisite direction; make up a series that just uses tree ring data, and no other proxies. It would be rather nice to see that in relation to time. It would also be nice to see delta T from non-trees vs. delta T from tree’s. It might then be possible to see what artifacts there might be in a tree ring proxy. This might show the relationship between tree ring grow and temperature.

66. Don Keiller
Posted Nov 16, 2007 at 7:03 AM | Permalink

Rob re#59. I would take your 10 pence worth more seriously had you not spliced instrumental NH temperature measurements (which are subject to question in their own right) to proxy reconstructions. This is a classic “apples and oranges” comparison which has been systematically discredited on CA.
PS any comments about Steve’s own attempts at dendroclimatology, or on Ababneh’s failure to discuss the Graybill BCP series in her thesis? Comments from a “dendro” would be appreciated.

67. Rob Wilson
Posted Nov 16, 2007 at 7:13 AM | Permalink

Don and Doc,
Esper et al. and D’Arrigo et al. are entirely tree-ring based NH recons.

No splicing has been done using instrumental data – look at panel C – the instrumental data (grey unfiltered / black – 30 yr spline) are just additional series on the graph.
Rob

68. Gary
Posted Nov 16, 2007 at 7:23 AM | Permalink

Agreeing with #42 DeWitt Payne, it might be useful to see spectral analyses of all of the proxies. If the frequencies between so many differently obtained series lined up, one could have a lot more confidence in the embedded signal being common to them all. Then for an interesting test, see how the tree-ring series compare.

69. MattN
Posted Nov 16, 2007 at 7:23 AM | Permalink

Esper et al. and DArrigo et al. are entirely tree-ring based NH recons.

And that’s your problem right there….

70. MattN
Posted Nov 16, 2007 at 7:25 AM | Permalink

So. How are the boys a Broke Stick Mountain going to attack and discredit this? Because you know they are.

71. Hans Erren
Posted Nov 16, 2007 at 7:46 AM | Permalink

I see a downward hockeystick:
2) Conroy Lake pollen (Gajewski, 1988);

72. Posted Nov 16, 2007 at 8:09 AM | Permalink

It sounds like each series was somehow calibrated locally. Is it correct to say that many other studies are calibrated to global mean temperatures?

73. Craig Loehle
Posted Nov 16, 2007 at 8:10 AM | Permalink

Thank you all for your comments and interest. My strategy in writing this was to make it as short as possible to avoid complications during review, being aware of how controversial it was. Thus plotting the 18 series was out of the question. If anyone would like to collaborate on doing this over with more data (more is probably available by now) and fancier stats, just email me (its on the ms). Most of the questions have been answered by others here, but let me clarify a few things. The data go to 1995 and were smoothed with a simple running 30 year mean, so the last data point is 1980. Since the data are not annual, and some have data only every 50 to 100 years, there is no decade which can be used to normalize them. The many methods used mean that concern about any particular proxy (e.g., oxygen isotopes) does not affect the result much. For the data, all are archived and most are at the standard data archive sites or are listed in the appendix. The suggestion that I list all the data NOT given to me would be to rile up people who might in fact give me data in the future. I did search the archives and did not cherry pick. I chose the data BEFORE looking at it based only on length and coverage. Why 2000 years? Because if you want to show a pattern besides a linear decline over the last 1000 years, you need at least 2000, but longer than this and there is not enough data. As for my code, anybody can get it, just email me. The E&E review was as rigorous as for any other journal Ive submitted to (of my 107 pubs). The GRL review was simply that they were tired of seeing such reconstructions and they did not even review it. I did not attempt hypothesis tests with only 18 data series and do not claim that it is a valid representation of global temp, and did not grid it or weight the series to get a global value.

74. bender
Posted Nov 16, 2007 at 8:11 AM | Permalink

Rob Wilson predicts the work will be ignored, but I don’t think it can be. Not completely anyways. If the major achievement of Loehle (2007) is to become part of a Wilson spaghetti-o-gram that stretches the envelope of possibilities vis a vis MWP vs CWP, that’s not a bad outcome.

Regarding a putative apples-oranges splice in Wilson’s graph. He has smoothed both instrumental and proxy series in the same way and is therefore not making an unfair comparison between time-periods. There is a big difference between overlaying multiple time-series on a single panel and blending them to blur the distinction. The only thing that is apples-oranges is the fact that there is error in the x direction on the non tree-ring proxies, whereas the tree-ring proxies are accurately dated, possibly 100% error-free. Don’t forget that when trying to determine how well the proxies match each other. Loehle’s graph does not honestly portray his error in the x-direction. The TR-based proxies do.

Nasif Nahle, a list is not a map. Not only do readers need a map of the sites, they need a map of the correlation field of individual proxy to mean.

75. MattN
Posted Nov 16, 2007 at 8:15 AM | Permalink

Because if you want to show a pattern besides a linear decline over the last 1000 years, you need at least 2000,

I’ve told people the reason Mann stopped at year 1000 was because he knew what was on the other side of it. The bulk of the MWP….

76. steven mosher
Posted Nov 16, 2007 at 8:22 AM | Permalink

RE 36. Geoff. I said I think not using tree rings was methodoligcaly interesting. My last comment
about ” subtle form of cherry picking” wasnt meant in a mean way. I’m thinking others may see it that
way. The justification for not using trees is clear.

77. Allencic
Posted Nov 16, 2007 at 8:30 AM | Permalink

Has it occurred to anyone that if Loehle’s paper had been written before MBH and had been taken seriously (as I believe it should) there might be no need for the IPCC and all the silly nonsense about carbon dioxide as a pollutant, carbon credits and footprints, the reluctance to build clean coal power plants, etc., etc. Mann would be teaching freshmen weather courses and Al Gore wouldn’t have the Nobel and Oscar. The rest of the world would just be going about its business in a climate that everyone could see just has some normal historical variation and is no threat at all. A lot of wasted grant money might have been available to help solve some genuine problems.

78. bender
Posted Nov 16, 2007 at 8:35 AM | Permalink

If you want a fruit salad, you gotta have cherries.

79. Pat Keating
Posted Nov 16, 2007 at 8:38 AM | Permalink

73 Craig

You probably know this but, if you use a recursive moving average, you can bring the average right up to the end of the series (1995?), at the cost of ‘missing’ the average for the earliest data points:
av(n) = av(n-1)*(1-a)+ a*x(n).

I believe that it is also less likely to introduce artifacts from the sharp edges of a simple MA filter window.

80. Posted Nov 16, 2007 at 8:45 AM | Permalink

#59,

In Panel B, I have scaled (same mean and variance for the period of common overlap – 1850-1979) all the series to NH temperatures (averaged from 0-90 degrees latitude using the CRU3 and/ocean data-set). This is likely not an optimal target for all the data-sets, but it is a compromise for this exercise. Panel C shows the same graph, but for the last 250 years.

i.e. variance matching. Can you tell how noise will affect these reconstructions, i.e. how to estimate confidence intervals ? Thinking about scaling error, maybe Craig has the most accurate reconstruction, and that’s why is has the largest variation 😉

81. Dave Dardinger
Posted Nov 16, 2007 at 8:50 AM | Permalink

re: #50 Richard T,

I see your point hasn’t been addressed, even by Dr. Loehle so I’ll do so.

Here’s the entire sentence you quoted part of:

After an extensive search, all data were used that had at least 20 dates over the 2000-year period.

What’s a bit confusing is that this is immediately followed by the list of proxies used. But the sentence above doesn’t state that “only” proxies with 20 dates were used. A better sentence would have been, “… all proxies were used that had at least 20 dates over the 2000-year period plus a few that had fewer dates.” Then a graph without the sparse sets could be added which would let us see if these proxies served as cherries or not.

82. bender
Posted Nov 16, 2007 at 8:53 AM | Permalink

Let us suppose for a moment that Loehle’s MWP is correct. Let us suppose further that the Anasazi people in the SW US did indeed go into decline as a result of a series of MWP “megadroughts”. What do you think bristlecone pine ring widths would look like under those circumstances, given they grow in a subalpine desert where “water is the essence of life”? Fat? Or narrow? Would this be consistent or inconsistent with the Sheep Mtn bcp update? Is it possible that Loehle’s data and Ababneh’s data are wholly consistent?

83. Craig Loehle
Posted Nov 16, 2007 at 8:54 AM | Permalink

Re: Bender’s comments: “Loehles graph does not honestly portray his error in the x-direction.”
I discuss this in the paper and devoted an entire ms to this issue (see my 2005 pub in Math Geology). The main effect of dating error on a multiproxy mean is to LOWER the amplitudes. Thus my reconstruction is conservative re the true magnitude of the MWP. Read my 2005 paper before replying.

84. Craig Loehle
Posted Nov 16, 2007 at 9:05 AM | Permalink

Re: Rob Wilson’s second plot. He scaled all series including mine to have common mean (ok) and variance (not ok). Scaling variance to be the same prevents one from seeing that one reconstruction has more amplitude than others. Also Rob: I did not do a calibration. each series had been independently calibrated on temperature inthe original pubs, so you need to look them up. this in a sense is a double blind study–I did not do the calibrations to temperature so I couldn’t have gotten the answer I wanted.

85. Craig Loehle
Posted Nov 16, 2007 at 9:11 AM | Permalink

I want to thank CA for inspiring this paper and also for a model of transparency. You will hopefully notice a lack of handwaving and obfuscation in both the ms and my replies.

86. bender
Posted Nov 16, 2007 at 9:11 AM | Permalink

I agree with rebuttal #83. My point was directed at others who might try mentally “wiggle-matching” two recons that ought not be “wiggle-matched”. (Wiggle-matching only works if there is no dating uncertainty.)

But to get back to this paper: knowing the direction of the bias (a good thing) does not excuse the obligation to plot robust confidence intervals. In this case that would include error in both x (date) and y (magnitude), and the confidence envelope around your MWP would be correspondingly wider. The only way to have a fair MWP vs CWP comparison is to have a robustly estimated confidence interval around each.

87. Hans Erren
Posted Nov 16, 2007 at 9:11 AM | Permalink

re 73:

For the data, all are archived and most are at the standard data archive sites or are listed in the appendix

Craig
I count only 17 references in your proxy list http://www.climateaudit.org/?p=2380#comment-161786 and there isn’t an appendix to the pdf.
Can you please give a list of used proxy urls?

88. Rob Wilson
Posted Nov 16, 2007 at 9:22 AM | Permalink

Craig,

Re: Rob Wilsons second plot. He scaled all series including mine to have common mean (ok) and variance (not ok). Scaling variance to be the same prevents one from seeing that one reconstruction has more amplitude than others. Also Rob: I did not do a calibration. each series had been independently calibrated on temperature inthe original pubs, so you need to look them up. this in a sense is a double blind studyI did not do the calibrations to temperature so I couldnt have gotten the answer I wanted.

the scaling makes little difference to your series except depressing the cooler period (e.g. the LIA) a little. The MWP levels are the same. I only did this to ‘fit’ the series on to the same scale. Personally, I think the TR NH series should be calibrated against NH summer temperatures. With multi-proxy records like yours and Moberg, the optimal season is not so easy I think.

Still – it would be very informative to see a stack plot of all 17/18 records

R

89. Jean S
Posted Nov 16, 2007 at 9:31 AM | Permalink

each series had been independently calibrated on temperature in the original pubs

IMO, this should have been stressed more in the paper! So now we have finally a quantitative reconstruction departing from the Mannian school (and what have been asked several times here in CA): first calibrate on the local temperature and then combine. This is an excellent start!

90. Rob Wilson
Posted Nov 16, 2007 at 9:50 AM | Permalink

Craig,
can you list the sampling resolution of your 17/18 proxy series?

I am troubled with the use of a 30 year moving average on a time-series that only has 20 observations over 2000 years.

What are the potential biases from aliasing and how could such effects impact the final mean series?

Rob

91. Rob Wilson
Posted Nov 16, 2007 at 9:52 AM | Permalink

also

I am interested in the following data:

12) SST reconstruction in the Norwegian Sea (Calvo et al., 2002);

can you give us the link as to where these data are archived
thanks
Rob

92. Jean S
Posted Nov 16, 2007 at 10:01 AM | Permalink

However, by giving up after rejection from GRL and going for E+E, it is quite likely that your series will never be taken seriously.

That would tell a lot about the quality of science by the people doing multiproxy reconstructions. I don’t think the key issue in Craig’s paper is the exclusion of the tree rings, IMO the key issue is the local vs. the global (hemispheric) calibration. The Mannian school of calibration on large scale temperature trends has not been, to my best knowledge, justified anywhere. Now we have a reconstruction, which takes a different approach and shows significantly different results as you graphs show. So the ball is now with the global calibration people as the local calibration seems much more sensible approach (at least to most people, I think).

93. DaveR
Posted Nov 16, 2007 at 10:14 AM | Permalink

Craig, it would be useful if you could publish the full comments from GRL. Did it get as far as referees or did the editor reject it?

94. Posted Nov 16, 2007 at 10:26 AM | Permalink

I dont think the key issue in Craigs paper is the exclusion of the tree rings, IMO the key issue is the local vs. the global (hemispheric) calibration.

Silly assumption, proxy responds to local changes instead of global.. How can you claim small enough CIs then 😉

95. Spence_UK
Posted Nov 16, 2007 at 10:28 AM | Permalink

By the way, GRL sent it back unreviewed because they were tired of seeing reconstructions.

If that is the case – and GRL has no bias – then we should not be seeing ANY more temperature reconstructions there in the near future. If we do see reconstructions that match a certain shape, that will tell a story in itself.

96. Posted Nov 16, 2007 at 10:32 AM | Permalink

I am troubled with the use of a 30 year moving average on a time-series that only has 20 observations over 2000 years.

so am i.

ending the series in 1995 of course is rather a CONVENIENT thing.

it removes about 7 of the 10 hottest years EVER from the record.

http://tamino.wordpress.com/2007/11/10/temperature-2007/#more-476

with the 30 years interval, that centers the last “warming” in 1980.

anyone got access to the data, to calculate a Mann hockey stick mean for the 1965 to 1995 period?

i think even the Mann data will look rather “cool” then..

ps: it would be really great, if someone with some time at hand could provide a link list to even just the abstracts of the proxy papers.
the most important data of course would be the year of the last data point used to calculate that means up to 1995.

pps: had to laugh on this one:

Whats a bit confusing is that this is immediately followed by the list of proxies used. But the sentence above doesnt state that only proxies with 20 dates were used. A better sentence would have been,  all proxies were used that had at least 20 dates over the 2000-year period plus a few that had fewer dates.

sounds slightly like “islands had to be evacuated” to me.

97. kim
Posted Nov 16, 2007 at 10:34 AM | Permalink

GRL was too tired to hear the different strains of the melody. The monotone just precedes the snore.
==========================================================

98. Rob Wilson
Posted Nov 16, 2007 at 10:36 AM | Permalink

JeanS,

Now we have a reconstruction, which takes a different approach and shows significantly different results as you graphs show.

lets not forget that the differences could also just simply be related to the use of a different set of proxies rather than the method.

This is of course easy to test. Normalise (same mean and standard deviation) the 17/18 series to a common period, average them together and then calibrate (regression or scaling) the final mean series to a NH target temperature time-series (Let’s call this the Esper/D’Arrigo approach as it is methodologically quite different to the Mann methods). Then compare with the Loehle E+E version.

Rob

99. Dave Dardinger
Posted Nov 16, 2007 at 10:47 AM | Permalink

Well, we’re getting a lot of suggestions of things that could be done, but given the abilities of the group here, most of these things can be done here in short order. I suppose when Steve gets time he’ll copy over the data to his data store and people can go to town.

100. steven mosher
Posted Nov 16, 2007 at 10:51 AM | Permalink

RE 85. Dr. Loehle. Thanks for sharing the paper and subjecting your self to questions. I won’t draw
comparisions between yourself and others in this regard. But, you can figure who they are. Well done.

101. Posted Nov 16, 2007 at 11:15 AM | Permalink

# 74

Bender,

Yeah, I know a list is not a map, but you wrote:

“The locations of the proxies are not mapped.”

Sorry… 😉

102. Posted Nov 16, 2007 at 11:15 AM | Permalink

honest question:

is 900-1100 considered to be the current “official” time frame of the MWP?

it is somewhat CONVENIENT to declare a 500 years period MWP.
http://en.wikipedia.org/wiki/Medieval_Warm_Period

(i m quite good at guessing lottery numbers. this week my bet is on the first 5 million numbers)

103. Posted Nov 16, 2007 at 11:17 AM | Permalink

Wikipedia? Heh!

104. Craig Loehle
Posted Nov 16, 2007 at 11:19 AM | Permalink

Bender wants to know what the x and y errors are. So would I. Dating error is rarely quantified and combining dating error and temperature estimation error have never been done to my knowledge. Feel free to publish a method. I used Jacknife and Bootstrap methods as the best I could do under the circumstances.
Re: 17 vs 18 records. Stott had 2 cores that were not close together that were used. Rob Wilson wants to calibrate the series against NH temp data, but the individual series are already calibrated against temperature. Please read some of them to see what they did. Sod implies that 1995 was convenient as an end point. That was as far as the data went. Sorry. Feel free to check the refs out.

105. Al
Posted Nov 16, 2007 at 11:26 AM | Permalink

Dr. Loehle, thank you for publishing this.

The method(s) you use for determining sensitivity to individual data series seems like it would be extensible to the treering data. I have a visual image of how I expect a ‘complete reconstruction minus bristlecones’ to compare with ‘complete reconstruction minus some other random series’. That is, Figures 2 & 3 where bristlecone pines are one (or several) of the series.

The impression from CA is that the bristlecones are crucial – but there aren’t published evaluations with the sort of graphic impact your Figure 2 or 3 would have with a bristlecone in the mix.

106. bender
Posted Nov 16, 2007 at 11:26 AM | Permalink

sod,
Look up “megadrought” while you’re at it.

107. steven mosher
Posted Nov 16, 2007 at 11:29 AM | Permalink

Re 99.

Ya and no FOIA required.

Posted Nov 16, 2007 at 11:29 AM | Permalink

RE: #47 – Hey punk, I am a scientifically trained engineer, at least in terms of my uni. I have a bachelors in geophysics and a masters in EE. If my masters was in a “science” and not “engineering” I’d properly label myself a scientist. (Some might even argue my bachelors alone allows that label).

(Folks – this is so typical of the ongoing smear campaign. They try to characterize us toothless hicks, without educations, sitting in red state double wides. That’s always how it is. The reality of well educated blue staters rising up against the high priests breaks the stereotypes. How dare we.)

Posted Nov 16, 2007 at 11:33 AM | Permalink

RE: #70 – see #47, a typical portent of things to come.

110. Jean S
Posted Nov 16, 2007 at 11:34 AM | Permalink

Rob(#98)

lets not forget that the differences could also just simply be related to the use of a different set of proxies rather than the method

Sure, it could be also an artifact of double low pass filtering, for example. I don’t know, I haven’t tried. Whatever the reason the local vs. the global thing (and the paper) can not be just ignored.

The test you propose is definitely worth trying. If you use the calibration time for the standard period and flip the series with negative correlation, then it is also Juckes’ CVM. That is such an excellent method as it recently passed flawlessly through an unbiased review as we all know.

111. Posted Nov 16, 2007 at 11:35 AM | Permalink

Hmm, after all, this one is not that different from Mann’s reconstruction:

Let’s compare AD1000 step with that illegal variance scaling step of Mann, and without PC1 fixing,

remarkably similar during 1400-present. Now, how to fix Mann 1000-1400.. Let’s see..

112. Posted Nov 16, 2007 at 11:37 AM | Permalink

with that illegal variance scaling

without, I meant. I don’t want to break the law.

Posted Nov 16, 2007 at 11:37 AM | Permalink

RE: #74 – Rob wants it to be ignored, too close to his own bread and butter for comfort.

114. Jean S
Posted Nov 16, 2007 at 11:39 AM | Permalink

SteveSadlov: Please send me e-mail (jean_sbls@yahoo.com), I have something off-topic for you.

115. Al
Posted Nov 16, 2007 at 11:40 AM | Permalink

Sod,

The span of the MWP depends entirely upon how long the temperature anomaly is above zero circa 1000. It is ‘the name of the bump’ – so whatever size the bump is -> that’s the size of the MWP.

It makes a tremendous amount of sense that anything witnessing “A strong MWP” is going to also have “A longer length of time where the average anomaly is above zero.” Witness the pictures in the “Thompson’s Thermometer” thread. A weak-to-no MWP reconstruction – like Mann-Thompson’s, can’t even claim the 200 years Wikipedia does. Note that there is a roughly 200 year period where Loehle’s reconstruction is above 0.3-or-so. (Just picture the origin adjusted up to 0.3)

Posted Nov 16, 2007 at 11:41 AM | Permalink

Re: #75 – The bulk of the MWP, plus the RWP, plus the Minoan WP …. wouldn’t want people to make any sorts of connections in their psyches between civilizational golden ages and warm periods (or any sorts of connections between dark ages, barbarian conquests, war, famine, pestilance, poverty and death, with cold periods).

117. Pat Keating
Posted Nov 16, 2007 at 11:42 AM | Permalink

re 47, 108
And I have a PhD in Physics from one of the top universities in the US, and a research reputation and publication record I am proud of. I think I could reasonably be referred to as a “scientist”, don’t you?

Posted Nov 16, 2007 at 11:47 AM | Permalink

Re: #77 – To be fair, there is something to be said for at least scaling back on the rise in GHG emissions. Until we better understand what the real sweet spot for CO2 concentration actually is (we don’t know it now) some caution is warranted. That, of course, does not mean I agree with the IPCC / Gore program. It does mean that “business as usual” is probably not currently defensible either. I would speed studies regarding what the CO2 sweet spot is (based on the paleo record). I would also aggressively pursue an uptick in scientifically driven global hazard analysis, employing Sigma methodology and advanced statistics and physics.

119. Pat Keating
Posted Nov 16, 2007 at 11:47 AM | Permalink

111
You need to get rid of that NH instrument splice, too. Half the world’s surface lies in the SH, and we know that is cooling…

Posted Nov 16, 2007 at 11:49 AM | Permalink

RE: #82 – Yes.

121. steven mosher
Posted Nov 16, 2007 at 11:51 AM | Permalink

RE 116.

You know if you look at the SRES, Wealthy futures are warm. Poor futures are colder.

Posted Nov 16, 2007 at 11:53 AM | Permalink

RE: #114 – Got it, will do later today.

123. richardT
Posted Nov 16, 2007 at 11:56 AM | Permalink

#104
See Blaauw M, JA Christen, D Mauquoy, J van der Plicht, KD Bennett, 2007. Testing the timing of radiocarbon-dated events between proxy archives. The Holocene 17: 283-288

124. Bill
Posted Nov 16, 2007 at 11:58 AM | Permalink

Doctor Loehle,

Well-done, and thank you for submitting to the gauntlett / gantlet.

I’ve seen several of these studies appear here and there, one at a time, over the last few years. But it is impressive to see them coalesce in a single graph. Mann’s hockeystick was a sort of “lamination” of other researchers’ data; this seems an appropriate and necessary reply, maybe even a tour-de-force. Other technically-savy writers here can advise you about the statistical pitfalls therein. I was blown away by seeing the “line-up” under your “Methods” section.

A good argument might start by making “points” one at a time, and establishing the validity of each. A commenter earlier asks that you detach a few of the individual components to show what they look like. I think this makes good sense, as a sort of “disclosure” of the merits of each research, and adds weight to the final combined graph. It might be worth the time and extra paper to overview some of these.

You’ve devoted a page to explaining why tree rings don’t work for temperature analysis, and you take pains to point out that “no tree rings were used…” but neglected to inform the readers how the methods you’ve chosen are efficacious or “proven” as accepted proxies. Perhaps this is a redundancy for some researchers, but then, I think your paper may be forging a path into new territory. You could bolster your argument by demonstrating how other processes of layer deposition provide a more readable, reliable result. As a non-techie, I’d be interested in knowing how general categories of this research (18 O, cave speleothems, SST, etc) have been validated.

Your first “reviewer” caught the business about uncovering the numbers on the timeline. This would help those of us looking for particular historical periods.

Now for the rottenest tomato of all: you use the word “quite” about 4-5 times, enough to be a little annoying.

Thanks for giving me the opportunity to line up with the real experts. It was fun.

125. bender
Posted Nov 16, 2007 at 12:04 PM | Permalink

#111 Nice.

126. Michael Jankowski
Posted Nov 16, 2007 at 12:12 PM | Permalink

ending the series in 1995 of course is rather a CONVENIENT thing.

it removes about 7 of the 10 hottest years EVER from the record.

http://tamino.wordpress.com/2007/11/10/temperature-2007/#more-476

Welcome to the “bring the proxies up to date” crowd, where we strive to actually see if the proxies are capable of identifying the warm extremes they are portrayed as having done so hundreds of years ago! Why don’t you invite your buddies at Tamino to join in the cheer?

http://www.climateaudit.org/index.php?p=89

The hockey team has been making excuses for years now. It’s nice to see such an argent proponent of the hockey stick such as you to join the crusade. I am sure that in no time, we’ll see a massive push from you and your cronies to update the proxies so that not only does this reconstruction come up close to present, but all the others do, too! Then none of them will “conveniently” end too soon.

127. MattN
Posted Nov 16, 2007 at 12:24 PM | Permalink

Hmm, after all, this one is not that different from Manns reconstruction:

I’ll say again. There’s an excellent reason Mann stopped at year 1000. He *knew* what was on the other side of it….

128. mccall
Posted Nov 16, 2007 at 12:27 PM | Permalink

Congratulations! Great effort.

===== future supplement info candidates ===

1) I’ll echo the stacked 17/18 proxy request.

2) In the Wegman Report (in testing an M&M conclusion), the major proxy contributors to the HS were identified (~19 BCP + 1 other), and there contribution to HS was determined — conclusion: no BCP ==> not much of a HS (validating M&M conclusion)! I would like to see similar effort, on the big contributors from 1 — I suspect Keigwin’96 Sargasso will be one.

===== re: 47 Webster Hubble Telescope =====
WHT is an historic (and hysterical) TROLL … major worshipper of Deltoid with a minor in Rabett worship … a virulent left-wing idealogue of weak physical science.

A sample WHT post from his blog, when a Professor Dan Epp posted regarding “Taken By Storm” review thread:

Professor Dan Epp said… I would love to witness a debate between you and the authors. Your refutations do not seem to have much technical or scientific substance. We all need a cause, but it seems to me that you are a little too shrill in your comments. What is your agenda. I do not pretend to be well versed in math and the sciences, but these guys seem to make sense. Dan Epp 7:56 PM
[snip]

129. bender
Posted Nov 16, 2007 at 12:27 PM | Permalink

I am inclined to agree somewhat with #127 and have said so before. The rate of warming in many recons during the period AD910-990 appears to be faster than what we see in the CWP. #59 hints at this as well.

130. mccall
Posted Nov 16, 2007 at 12:30 PM | Permalink

Note: I deliberately omitted posting a link to his post(s). Use a search engine to track, if you must; but I don’t think he’s earned the hits.

131. Posted Nov 16, 2007 at 12:40 PM | Permalink

Pat, am I a scientist? 😦

Craig Loehle,

It would be interesting to insert the graph of the Solar Irradiance reconstruction in the last 400 years on any one of your graphs. I made it a few minutes ago and it is disturbing… The correlation is closer from your graphs than from the Hockey Stick. Hockey Stick construct is a funny story, really. It opposes to nature logics hah!

132. steven mosher
Posted Nov 16, 2007 at 12:40 PM | Permalink

I know I asked this question before and have forgotten the answer ( Gunnar syndrome) Why would
you use a centered Smooth? I can see averaging the past into the future ( a trailing MA)
kinda carrying information content forward… but what is the physical justification
for a centered Smooth…. ah wait..hmmm. Anyway, Explain away. I’m wearing golf shoes
and don’t want to tread on my tender parts.

133. mccall
Posted Nov 16, 2007 at 12:50 PM | Permalink

re: 127 & 129, I’m of the opposite view.

In the HT spaghetti charts, a relative maximum often occurs at ~1000. Therefore the team can safely move back ~300 years prior to MWP @ 1000 relative maximum, and extend the “1990s warmest decade in 1300 years” claim as was done in AR4 and summary policy doc’s. This was just one big DUH for me, since I subscribe to a global MWP.

Magician’s NOTE: IMO, this 1300 year AR4 claim enhancement also served to mask the “divergence problem” we all expected to be addressed straight on in AR4. Rather than take the heat for publishing of analysis of divergence proxy reconstructions in AR4 & doc’s, the consensus catastrophic AGW minds diverted attention (of the HS and AGW faithful) to an extended handle end of the hokey tick. Pay no attention to the divergence behind the blade of the HS, JUST LOOK AT HOW LONG WE EXTENDED THAT HANDLE!

134. Craig Loehle
Posted Nov 16, 2007 at 12:50 PM | Permalink

Mccall said “2) In the Wegman Report (in testing an M&M conclusion), the major proxy contributors to the HS were identified (~19 BCP + 1 other), and there contribution to HS was determined  conclusion: no BCP ==> not much of a HS (validating M&M conclusion)! I would like to see similar effort, on the big contributors from 1  I suspect Keigwin96 Sargasso will be one.”
This is why I did the 2 sensitivity plots. Dropping any 1 series (fig 2) or any 4 series (fig 3) does not change the conclusion. No series were weighted, they all had equal weight of 1.

135. Posted Nov 16, 2007 at 12:51 PM | Permalink

Instead being criticizing inconsequential omissions in Dr. Loehle’s paper, let’s try to correlate his findings with other known data; for example with solar irradiance. If that works, that is, if it is tied with other theories, then the effort of Dr. Loehle is important and creditable. I think you know the law of truth of correspondence.

136. steven mosher
Posted Nov 16, 2007 at 12:51 PM | Permalink

RE 129.

Bender I have a Gunnar question. ( GQ for short)

I’m puzzled on this Proxy and teleconection question.

A tree in colorado is teleconnected to the hemisphere.

A thermometer in Denver only correlates with thermometers 600 miles away.

For grins I did a little study to see how accurately thermometers in the US could serve as proxies
for NH temp. I should prolly go do that again.

I think that led me to conclude that we should core trees every year and get rid of NOAA.

137. mccall
Posted Nov 16, 2007 at 12:52 PM | Permalink

134 — thank you!

138. MattN
Posted Nov 16, 2007 at 12:53 PM | Permalink

Wait wait wait….Lemme get this straight!

One of “us” creates a reconstruction that uses proxies ending in 1995, and that’s bad. But one of “them” creates a reconstruction that uses proxies from the 1980s (Graybill) and that’s just dandy?!?!?

L.M.A.O!

139. steven mosher
Posted Nov 16, 2007 at 12:57 PM | Permalink

RE 128.

Feed trolls ground glass in raw ground chuck.

They bleed out eventually.

140. Craig Loehle
Posted Nov 16, 2007 at 1:01 PM | Permalink

Mosher: why use a centered smooth? That is the mean temp of that 30 year interval. I am not doing forecasting, just trying to deal with data that are not annual.

141. MrPete
Posted Nov 16, 2007 at 1:05 PM | Permalink

Doesn’t a centered smooth also (largely) avoid endpoint issues? Most of us find it difficult to accurately account for the future in moving-average plots.

Posted Nov 16, 2007 at 1:11 PM | Permalink

RE: #116 – BTW, the late first millenneum was an underreported civilizational golden age in many parts of Europe. Think Charlemagne, the earliest seeds of the university system, the proto French state, the first serious public buildings built since the late 400s, etc.

143. Posted Nov 16, 2007 at 1:11 PM | Permalink

Review of Loehle 2007

As a climate scientist, and one currently working on climate reconstructions (with M.Mann on top of that !), one may be surprised to read that i welcome this study as a useful “What if ?” experiment. I therefore agree with bender (#16) that “the approach is novel and the results worthy of publication”. Unfortunately, this is the only positive thing that can be said about it.

Methodological flaws are utterly gruesome – and they are all the more shameful coming from a Ph.D. in Mathematical Ecology.
The argument that his “strategy in writing this was to make it as short as possible to avoid complications during review” (#73) is quite pathetic. Why not, then, bypass the whole ‘methods’ section, and simply give us a curve without any explanation ? Brevity is the soul of wit, yes – but when crucial information is missing, this “science” has an odd scent of disinformation. While some CA readers seem satisfied with any amount of hockey-stick bashing – whether well founded or not – CA will only be taken seriously by the climate science community when the same standards of scrutiny are applied to both sides of the debate. So are you guys skeptics or just denialists ? If you truly are the former, then you’ll find quite a bit to be skeptic about here.

In random order :

– FROM PROXIES TO TEMPERATURE :

– Relationship of each proxy to *local* temperature is not even discussed. We are just shoved a list of references (hey Craig , have you heard of tables ? They are a great means that scientists use to convey information clearly). How is it that tree-rings are seen as the penultimate antichrist but that, to take but one example, d18O of speleothem calcite (e.g. Holmgren et al., 1999) is a flawless paleothermometer ? Shouldn’t one discuss one by one, and with great care, the pros and cons of each proxy as a temperature recorder ? d180 in forams is a notoriously flawed temperature proxy, is being replaced by Mg/Ca where possible, and one can only surmise why the Keigwin[1996] series is here.. Is it just a form of screening for proxies with a low ‘hockey-stick index’ (in McIntyre parlance) ?

Say what you want about MBH98 : in spite of its many flaws, it made extremely explicit attempts at estimating error bars. One would expect this work to have paid attention to past work and up the ante where it can.

minor comment : Dahl Jensen et al (1998)’s main contribution is a borehole measurement of *actual* temperature. “Borehole d180 temperature” is a climate neologism . Perhaps that’s what is meant by “novel approach”.

– Relationship to global temperature is even more elusive. How is each proxy representative of a particular area ? What is its geographical weight in the final “mean” series ? Are we to assume the curves displayed are just the arithmetic average of all proxy-based temperature series ? Are they weighted differently depending on their ability to faithfully record temperature over the historical period (aka “calibration”) ? It is disquieting that so little is said about this crucial step. If i were reviewing this paper for GRL (i have in the past), these would certainly be grounds for immediate rejection. As in : “this cannot possibly be an honest and serious study”.

– TIMING : the author does a nice job of discussing how dating uncertainties might bias the result. The similarity between the timing (not necessarily the amplitude) of this and other, tree-ring based reconstructions (which – should it upset CA readers – have the great advantage of being exactly dated) is encouraging and is an important empirical confirmation of the relevance of this method ( see Rob Wilson’s figure, #59). At first glance, ignoring tree-rings might be seen as throwing out the baby with the bath water, but it clearly seems to affect dating errors less than what one might think.
On the other hand, could it be that some proxies conspire to show a synchronous MWP where there wasn’t (cf Hughes and Diaz, 1994) ? It would be interesting to devise “pseudo-proxy” experiments with a messed-up time axis and gauge the likelihood of a MWP popping up by chance alone. This, actually would be quite novel…

– SMOOTHING : a running mean is essentially a multiplication by a gate function , which – as the author must be well aware of – amounts to a convolution with a sine cardinal in frequency domain. This introduces sidelobes that distort the signal, and would presumably mess up the edges of the timeseries. Oddly enough, the 1970-1999 period has gone AWOL…. One would like to see other smoothing methods applied to remove that doubt.

– VALIDATION :
this is where the paper shatters all publication standards. There is :
– No error analysis (in Y, not to mention X)
– No significance testing.
– No cross validation.
Impressive ! Where are the CE, RE, and most importantly R-squared statistics that are so dear to ClimateAuditers ? How are we supposed to guess whether the reconstruction has any skill ? Or is that irrelevant because ‘temperature date are flawed’, by virtue how displaying a very inconvenient warming since 1850 ? (some 1940-1960 aerosol-induced cooling notwithstanding) ?

In summary, this is a rather obscure compilation of proxy data, with a conciseness in methodology that borders on farce.

I’m willing to lend a mildly sympathetic ear to the Wegman claim that all climatologists are in bed with each other and even to the conspiracy theory that Nature and Science are personal allies of the Mann family and have sworn the death of ClimateAuditors . But let’s be serious here for a minute ! What on Earth do you expect from a GRL editor when they see such a piece of junk in their inbox ? It leaves much to say about E&E’s standards. Are we to surmise than any anti-Global-Warming or anti-hockey-stick paper gets a go ?

McIntyre & McKitrick (GRL, 2005) showed much competence in their rebuttal of the hockey-stick . Though i have my issues with that paper, it is a legitimate criticism of MBH98, one that was deservedly published, and is precisely the kind of work that lends credence to ClimateAudit. The latter community would be well-inspired to apply the same rigorous standards to all climate studies, regardless of their scientific or political outcome. It’s hard enough sifting through the comments of ignorant global-warming-denialists on this site – but so far i still do because of some very incisive and insightful climate investigations that question (and i believe, ultimately enrich) mainstream climatology. CA must now put their mind where their mouth is. Mr McIntyre, the ball is in your camp.
Are you with science, or are you for the obscurantists ?

144. MattN
Posted Nov 16, 2007 at 1:12 PM | Permalink

Mccall:

Not sure if I my point was vague. If you look at the reconstruction in #111, you’ll see that by 1000AD, we were well on our way down from the peak of the MWP, in fact there appears to be a very quick drop right at Y1K. By 1000, the bulk of the MWP was done. I submit that Mann knew (or strongly suspected) this to be the case and stopped at Y1K on purpose to cut it out. I suspected this when I saw the GRIP data. I also submit that if the years 700-1000 in any way strengthened Mann’s case, they would have been included in his reconstruction. But they weren’t. He conveniently stopped at Y1K, and served up a giant cherry pie.

145. Larry
Posted Nov 16, 2007 at 1:13 PM | Permalink

136

I think that led me to conclude that we should core trees every year and get rid of NOAA.

Makes sense to me. All the problems with sensor drift, site problems, maintenance issues with fans, pesky calibrations with messy ice baths and boiling water, all go away, with the amazing new patented Mannomatic Treemometer™!

146. Craig Loehle
Posted Nov 16, 2007 at 1:20 PM | Permalink

I want to thank UC for the plots in 111. Note that tree rings may be valid for COOLER periods, thus Mann’s results match from 1400 AD to present, but not before, when my results are WARMER.

147. Posted Nov 16, 2007 at 1:31 PM | Permalink

JEG,

Huh… Is the Universe static?

148. steven mosher
Posted Nov 16, 2007 at 1:34 PM | Permalink

RE 140. Dr. Loehle. The choice of a smoothing approach ( so I’ve been lectured here) can have some
consequence. As Long as you supply the data and other folks can smooth away with their favorite filter
I have no Issue. The issue of centered versus trailing isnt one of forecasting in my mind.

Pat Keating mentioned an approach to allow your curves to not toss away data at the end of the time series.
So, I’m just curious and ignorant as to why people would even use a centered approach as that averaging
doesnt reflect any underlying physical reality. Acausal was the word people used. This is an open question
not a critcism.

Again, As long as the underlying data is there and people can filter to their hearts content, whatever method you
choose to choose is your choice.

149. Sam Urbinto
Posted Nov 16, 2007 at 1:35 PM | Permalink

pk asked in 15 “What ice”

“The ice” is when something challenges the trees or temperature well, the argument shifts to “but the glaciers are receding” and/or “but the artic ice is melting” so “You can see the global warming!” (usually followed by “You’re a denier!”) So argument-wise, they “run to the ice”.

150. Craig Loehle
Posted Nov 16, 2007 at 1:39 PM | Permalink

For TEG in 143. My my, aren’t we upset! If I take the instrumental record for a state over the 20th century and let’s say the records are widely dispersed. I can compute the anomalies and get a mean for each year. Right? Is this not what GISS does except they have unequal number of stations in any given region, so they weight them (more weight per station in sparse areas). If there is something wrong with this operation, you should tell Hansen. For the error bars, I assume that either the reader knows about the problems with the various proxies or can go read my 17 citations. But: what is known about the various types of error is not readily converted into error bars (go ahead, tell me how to do it), so I did fig 2 and 3 as the best that can be done with this type of data. 1970 to 1999 are not AWOL. The data only go to 1995 and 1980 is the last 30 year smooth that can be computed. Try reading the paper after you cool off. Cross-validation and RE and R2 are only relevant if you have a MODEL and I did not compute a regression or any model. Are there RE or crossvalidation stats or R2 on the GISS 126 year temperature history? At each point what I have is the mean of the 18 smoothed proxies. That’s all. I do not claim that it is a valid global mean and of course it is not. But that is all the data that existed as of 1 year ago in public archives that I could find. We will never have 1000 datasets to get a valid global 2000 year mean. I said that for these 18 points scattered across the globe, the MWP appears real.

151. steven mosher
Posted Nov 16, 2007 at 1:43 PM | Permalink

RE 141.

What endpoint issue? If you use a centered smooth you have an operation that does not reflect
any physical system and you arbitraily toss points from the end of your series.

On the assumption that recent chronology is more accurate than early chronologies or rather that closer dates
have less error than past dates. And on the assumtion that near term measurements are less subject to
noise and error than older measurements… THAT IS, on the assumption that error in chronology (x) increases
as we go back in time and that error in response (y) increases as we go back in time, then I would not
center my filter.

( ducks as tomatoes fly)

152. bender
Posted Nov 16, 2007 at 1:53 PM | Permalink

JEG,
To what degree was your #143 review written independently of my #16? Thanks in advance.

153. steven mosher
Posted Nov 16, 2007 at 1:54 PM | Permalink

RE Myself. Opps Dr Loehle. Nevermind. I just got your point about prediction.

154. Posted Nov 16, 2007 at 1:54 PM | Permalink

Wikipedia? Heh!

i will very gratefully accept any link to an official definition of the MWP time frame. please lead me there!

remarkably similar during 1400-present.

yes, very similar up to about 1980. just missing the hokeystick part.

Sod,

The span of the MWP depends entirely upon how long the temperature anomaly is above zero circa 1000. It is the name of the bump – so whatever size the bump is -> thats the size of the MWP.

this would be fine, when looking at ONE study. if you use multiple studies, it is getting weird:

lets put some random noise between 0 and 2000. if we get a spike between 800 and 1300 it is a point for MWP, if the spike is between 1960 and 2000 it goes to Mann. now guess what..

Welcome to the bring the proxies up to date crowd, where we strive to actually see if the proxies are capable of identifying the warm extremes they are portrayed as having done so hundreds of years ago! Why dont you invite your buddies at Tamino to join in the cheer?

i would prefer proxies to be up to date! but i understand, if people can t manage to do it. but doing a hockey stick debunk, while EXCLUDING the hockey stick period is slightly stupid.

this paper has tree ring data up to 2003 and produces a hockey stick:
http://www.wsl.ch/staff/jan.esper/publications/Buentgen_2005_CD.pdf

Doesnt a centered smooth also (largely) avoid endpoint issues?

doesn t a centered snooth also (largely) avoid results that have HOCKEY STICK form?

155. Peter Thompson
Posted Nov 16, 2007 at 1:55 PM | Permalink

Re: #143 Your use of the term “denialist” belies your claim to be a man of science. You’re a priest, and you just called several people heretics.

156. Pat Keating
Posted Nov 16, 2007 at 1:56 PM | Permalink

140
The recursive averaging approach is also computationally very efficient (although that matters less nowadays). It would reduce the JEG-type criticism re sinc function sidelobes from the sharp edges of the simple averaging window.

157. Robinson
Posted Nov 16, 2007 at 2:02 PM | Permalink

#131 can you post it up so we can take a peek?

158. bender
Posted Nov 16, 2007 at 2:09 PM | Permalink

Re #111
The divergence period from AD1000-1100 looks something like the modern divergence pattern.

159. steven mosher
Posted Nov 16, 2007 at 2:09 PM | Permalink

Dang. I just read JEG. Can you imagine such a post being posted on RC?
BLT ( brave little Twit) even posted his initials.

I wonder. will JEG now run the Gantlett? ( curses on you guys)

Answer Puppy JEG. Are you gunna sack up or run away?
Will you submit to all questions or RTFA: run the * away?

That’s the first question. YES OR NO.

Second question: name rank and serial number. Own up or be Pwnd.

160. trevor
Posted Nov 16, 2007 at 2:13 PM | Permalink

Re #143: JEG, you did note, didn’t you, that Steve McIntyre, in the header for this post stated:

Ill try to comment later but have some other obligations right now.

And so far as I can see, he hasn’t yet turned his attention to Craig’s paper.

Can I suggest that you might take that into account in your comments.

161. Reid
Posted Nov 16, 2007 at 2:16 PM | Permalink

sod,

Resistance is futile.

162. Sam Urbinto
Posted Nov 16, 2007 at 2:20 PM | Permalink

I too am curious about the RE CE and R etc I was also wondering about the lack of weighting, assuming all the proxies being used aren’t at the same levels. I’m guessing that’s the “each series had been independently calibrated on temperature in the original pubs”

Why don’t you wait until Steve has a chance to tear into it before asking for the information, JEG? I’m not qualified to do any kind of analysis, myself. And while you’re waiting, perhaps, if you know them, you can ask some of the dendro guys with unarchived data to archive it too.

Since you’ve stopped by and thrown yourself into the heart of us “ignorant global-warming-denialists” perhaps you can explain to us how you get 2.5 C of warming from doubling carbon dioxide in the atmosphere and increase our knowledge levels. I’d also like to know your take on the relationship of the GHG and how they react with airborne and ground level particulates, clouds, cities, freeways, farmland, forests and deforestation, and the ocean on the entire cooling/heating system.

And why an extra 100 ppmv over 170 years of a single GHG that absorbs IR at 4.3 and 15 micrometers, bringing it up to ~.04% of the atmosphere by volume plays such a huge roll in the 125 year +.7 C trend rise in the global mean GHCN-ERSST anomaly.

Or why land-use change isn’t spoken of more. Certainly the IPCC counts both.

Oh, and then explain this graph to me, I don’t understand it.

I must have something wrong, it shows temperature, O18, solar variation, carbon dioxide and methane levels are all in synch. That can’t be correct. Also strange is the 10 degree centigrade temperature swings 4 times in the last 420,000 years.

A sentence or two on each would be helpful to all of us I think.

163. Reid
Posted Nov 16, 2007 at 2:25 PM | Permalink

JEG,

Denialist? You’ve hurt our feelings. We are heretics in the tradition of Copernicus, Galileo and Einstein. Or at least I think so.

164. Craig Loehle
Posted Nov 16, 2007 at 2:28 PM | Permalink

Even though I posted this above, people keep asking about validation stats. The temperature series were all derived from regressions of proxies against LOCAL temperature over recent periods in the original pubs. All of these have R2 stats etc. I did not compute a model or a regression, so it is not possible to compute goodness of fit. Cross-validation and RE and R2 are only relevant if you have a MODEL and I did not compute a regression or any model. Are there RE or crossvalidation stats or R2 on the GISS 126 year temperature history? Also, I did not do a formal hypothesis test, as this is not supported by the data.

165. Geoff Olynyk
Posted Nov 16, 2007 at 2:30 PM | Permalink

#143 JEG, I agree. I find this study clear enough in its methodology, but lacking in novelty and rigour. All that has been done here is to collect a couple dozen paleoclimate studies, and then smooth and average them. While it is important to get a non tree-ring based multiproxy study into the peer-reviewed literature so that the idea can gain credibility, it should have been a much more comprehensive one than this. In particular, discussing the limitations of each of the proxies which were used, not just explaining why tree-rings weren’t should have been a mandatory requirement for publication.

For the commenters here, please take a hard look at your own biases when making comments. Just because the study has a result you like isn’t a valid reason for excusing its flaws. That kind of reasoning is what has largely driven me (and many others, I suspect) here from RealClimate.

166. bender
Posted Nov 16, 2007 at 2:33 PM | Permalink

Remember: that the study has “flaws” doesn’t mean the recon is inaccurate. Be careful not to be too dismissive.

167. Judith Curry
Posted Nov 16, 2007 at 2:34 PM | Permalink

I’ve been watching this thread with great interest, since climateaudit hasn’t typically (to my notice anyways) taken on a serious critique of a critique of MBH (if that is too many critiques, basically an anti-hockey stick paper). If SteveM and the posters can make detailed and constructive critiques of Craig’s paper (and engage constructively with Craig in further work), then the credibility of this site in terms of bonafide scientific skepticism will increase (as opposed to denialist/contrarian idiots or whatever the guys at Pharyngula were saying).

With regards to JEG’s post, i hope that JEG and the posters can settle down into a constructive discussion of topics directly related to Craig’s paper and perhaps broader hockey stick issues (rather than scaring JEG away by asking him to defend everything in the IPCC). Seems like JEG has some deep knowledge on the topic, and in spite of some flames, JEG actually had some nice things to say about climateaudit and esp SteveM.

This could be really interesting and informative.

168. pk
Posted Nov 16, 2007 at 2:35 PM | Permalink

#157,
I’m not Nasif and this isn’t the prettiest overlay, but Loehle and TSI reconstruction.

169. Jeremy Friesen
Posted Nov 16, 2007 at 2:37 PM | Permalink

I enjoyed reading JEG’s criticisms. Most, despite a slightly aggravated tone, were quite reasonable and worth considering. It’s nice to have someone like JEG inject a bit of realism from the climate science “in-crowd” in CA. It’s good to see Craig responding to them. I hope to see JEG come back for a rebuttal. Hopefully he will find the climate here conducive to reasonable argument and response.

170. bender
Posted Nov 16, 2007 at 2:44 PM | Permalink

Cross-validation and RE and R2 are only relevant if you have a MODEL

You have a model. Your model is that the mean of the sample is a meaningful descriptor of the population that was sampled. GCV can be used in conjunction with resampling, which is sort of what you tried to achieve with your leave-some-out sensitivity analysis. The concept is great. Maybe you are not familiar with these kinds of validation techniques, but that doesn’t mean they don’t exist. They do. [Too bad the dendros are guilty of the same thing, however.] Also, remember each proxy itself is subject to its own error (measurement sampling, calibration), and this is something that can be included in a resampling approach. Something the dendros systematically choose to ignore in what appears to be a concerted effort to downplay uncertainty.

171. Craig Loehle
Posted Nov 16, 2007 at 2:45 PM | Permalink

I hope JEG (and all) will notice that I did not engage in ad hominim in responding to him but tried to answer his concerns.
By the way, I am noting all the comments and would not mind redoing this paper with more data (or with certain data dropped if it needs to be) and fancy smoothing etc.

172. Reid
Posted Nov 16, 2007 at 2:49 PM | Permalink

Jeremy Friesen says: “I hope to see JEG come back for a rebuttal.”

I hope JEG doesn’t beclown himself by calling CA denialist. Steve M. has never denied AGW. Let’s be precise here. CA and Steve M. has denied Mann’s Hockey Stick not AGW. Overturning the dominant paradigm is an unintended side effect.

173. bkc
Posted Nov 16, 2007 at 2:53 PM | Permalink

Re #159 Steven,

Second question: name rank and serial number. Own up or be Pwnd

Click on Julien’s intials. Ditto on Dr. Curry’s final comment.

174. bender
Posted Nov 16, 2007 at 2:59 PM | Permalink

Drs. Curry (Judith) and Liljegren (lucia),
You share a common interest in trying to describe time-series with harmonic structure to it (LJ: temperature, JC: hurricanes). We were working on this last year when we got buried by an avalanche of papers by Emanuel et al. on hurricane pattern analysis. JEG is maybe even interested in this topic too.

I suggested that John Creighton’s MATLAB code for orthogonal filtering could be converted to R to make some better hurricane prediction models. (Timely, given David Smith’s recent observations.) I have yet to relocate that code, but it is probably worth revisiting. (Such a model would have predicted a low hurricane count for 2007.)

175. Posted Nov 16, 2007 at 2:59 PM | Permalink

Even though I posted this above, people keep asking about validation stats. The temperature series were all derived from regressions of proxies against LOCAL temperature over recent periods in the original pubs. All of these have R2 stats etc. I did not compute a model or a regression, so it is not possible to compute goodness of fit. Cross-validation and RE and R2 are only relevant if you have a MODEL and I did not compute a regression or any model. Are there RE or crossvalidation stats or R2 on the GISS 126 year temperature history? Also, I did not do a formal hypothesis test, as this is not supported by the data.

sorry Craig, but providing the last data point (time and some value, even if only in comparison to some “mean” of the proxy) would be an ABSOLUTE minimum requirement to give some sense to this study.
adding the number of data points is another one.

that none of the “auditors” so far have asked for this, is rather bizarre.
it is not going “hockey stick” if half your proxies end in 1950… (and are “smoothed” till 1995..

“dig it up in my literature” is not an option with such a fundamental question..

176. bender
Posted Nov 16, 2007 at 3:03 PM | Permalink

I think I found it: http://www.climateaudit.org/?p=692#comment-79684

177. Sam Urbinto
Posted Nov 16, 2007 at 3:10 PM | Permalink

Craig, I wrote that before I read what you said in reply…. I should have said I was curious but then I remembered what you said about the studies themselves; you didn’t do proxy work, you did your work with proxy results from papers. But bender makes some good points.

Judith, those people over at phary were for the most part a rabid insane pack of snarling dogs, weren’t they. However, with the tone and some of the wording, if he’s been reading CA, I would think he would have known the kind of response he’d get. Be that as it may, I hope JEG sticks around and does educate us more.

Those who’ve been a litte rough, remember, Craig’s A) opening himself up to this process B) asked to be criticized C) hoping to make a better paper. Even if some of the phrasing was rather hostile, that’s what this thread is here for. I think that’s good.

On the other hand, the pattern a lot of times is this: Person comes in and is slightly hostile. Pointed revelent questions are asked. Circular argument ensues involving begging the question, obfuscation, hand-waving, various logical fallacies with cute little names in Latin thrown around, dodging and weaving, etc. Person eventually just stops coming, never answering any questions. If they come back, the do so after the issue’s blown over and they avoid the topic. However usually they’re trying to make excuses for their work, not commenting on somebody else’s…

178. Craig Loehle
Posted Nov 16, 2007 at 3:17 PM | Permalink

It may interest all of you that I decided on my analysis method and wrote the code for it when I only had 8 data sets, so I did not change the method to get the answer I wanted. Re: Bender’s comments about error bars. It seemed like the big issue was whether particular series were unduely unfluencing the outcome. To test this I did the jacknife and bootstrap tests–which by the way are also standard stat methods. To compute error bars I would need to consider measurement error for the proxy (usually unclear from the pubs), model error for the temperature conversion for that proxy from their regression, the possible bias due to the proxy (suspected but often unknown), dating error (also often unknown), and then propagate all four of these for each of the 18 series (using a monte carlo propagation?), and then combine them somehow. In a perfect world, perhaps it could be done. Anyone have an example pub where someone did this? Since I did not do specific hypothesis tests, it is up to the reader to consider that there is of course error in my reconstruction that probably looks something like fig. 3 if you could compute it.

179. Mike Noble
Posted Nov 16, 2007 at 3:18 PM | Permalink

Re: #167

“since climateaudit hasnt typically (to my notice anyways) taken on a serious critique of a critique of MBH (if that is too many critiques, basically an anti-hockey stick paper)”

Dr. Curry, I seem to remember quite a few CA critiques of MBH critiques, a quick search pulls up:
this,this and this, and I think there are also some critiques of Burger and Cubasch 2005.

180. Sam Urbinto
Posted Nov 16, 2007 at 3:21 PM | Permalink

Sorry, I messed up that middle paragraph, the last two sentences are switched or should have been a separate paragraph. I wasn’t trying to link Phary and JEG together! (He was much nicer in his post….)

181. bender
Posted Nov 16, 2007 at 3:21 PM | Permalink

Re #178

Anyone have an example pub where someone did this?

No. That’s why it would be cool to do it. Because it would be the correct way to do it.

182. steven mosher
Posted Nov 16, 2007 at 3:21 PM | Permalink

RE 165.

I like what Geoff has to say. As I noted the approach of tossing out all tree rings has a certain appeal.

As for what follows after that methodological choice, I’m going to have to listen to folks like UC, JeanS, bender, Willis.
IN the past they havent
been shy about pointing out errors. The point of the Gauntlett idea was to allow the paper to undergo
a harsh but fair.. (no motive hunting ) beating. maybe I’m just used to the Redteam/blue team paradigm
where you expected to beat an idea senseless and se if it it can still stand.

Hi Dr. Curry!!! Did you read Lucia’s response to you about your hamming filter question? (he/she) gave
a nice explaination to your question. I think it was on the hurricane thread. I can check if you like.

183. Jean S
Posted Nov 16, 2007 at 3:22 PM | Permalink

I usually do not respond to trolls and especially for the ones with rude and aggressive language, but I make an exception solely because of the respect for Judith Curry.

#143 (JEG):

It would have been nice if you had tried to limit your comment to the scientific points only. Now it is just an example of an aggressive, overly lengthy piece of an attack filled with Mannian style insults. I try to ignore those and answer to the actual content. In order:

Relationship of each proxy to *local* temperature is not even discussed.

Yes, that’s a valid point. However, that’s not the essential point of the paper, and you can find that information from the original publications. There can not be any real error bars as they depend from the error bars of the original series (which I suppose do not even exists in all cases) among other things.

extremely explicit attempts at estimating error bars

You must be joking here.

How is each proxy representative of a particular area ? What is its geographical weight in the final mean series ?

Good points, and I would have also wished for such discussion. But this is a good project for you: check the locations of the series used and calculate the optimal weighting and post it here. I’ll promise to comment.

Are we to assume the curves displayed are just the arithmetic average of all proxy-based temperature series ?

Yes, that what is says in the paper. In scientific papers things usually are the way it is said in the paper.

Are they weighted differently depending on their ability to faithfully record temperature over the historical period (aka calibration) ?

No, according to the paper. BTW, your definition of “calibration” is rather weird.

TIMING

Is there a point included?

SMOOTHING

You connect a running mean to a filter, Linear Filters 101. What’s the point? I’d also like to see the results with other low pass filters. Let’s do the following: you give the specs, and one of the CA filter experts (MarkT, Spencer comes to my mind immediately) gives you the filter and we’ll try.

No error analysis (in Y, not to mention X)

As I said earlier, probably too hard to with the data used (i.e., in scientific BS: “not in the scope of the paper”).

No significance testing

Of what? How would you do that?

No cross validation.

What do the Figures 2 and 3 describe?

Impressive ! Where are the CE, RE, and most importantly R-squared statistics that are so dear to ClimateAuditers ? How are we supposed to guess whether the reconstruction has any skill ?

You are confusing something here. CE & RE are essentially associated with calibration (regression), there is no regression in the paper. I agree that it would be nice to see some prediction error numbers (with respect to instrumental temperature reconstructions). BTW, “skill” is a Mannian term which was unknown also to Wegman and his colleagues. Also you are mistaken if you think CE or RE would be somehow “dear” to most CA readers.

That seemed to be all. Please let me know if I missed any serious points.

184. bender
Posted Nov 16, 2007 at 3:26 PM | Permalink

Re #178

To test this I did the jacknife and bootstrap testswhich by the way are also standard stat methods.

Could you point to the paragraph in the methods that describes this procedure? I’m afraid I missed it.

185. Craig Loehle
Posted Nov 16, 2007 at 3:27 PM | Permalink

sorry sod 175, unclear on what you mean. If you mean by data point the values in fig. 1, they are posted on my web site (see fig 1 caption). The number of data points where? It is 18 series in general at each time, but not all series cover the time uniformly (some have gaps). You want a plot of how many series at each time? Probably over 15 at any given time point. Using bold letters does not make your question more clear, that is just shouting.

186. captdallas2
Posted Nov 16, 2007 at 3:28 PM | Permalink

My comment, prior to reading all the others, was the lack of error bars and the 1970 ending should be addressed. JEG makes valid points in an edgy manner, but valid, that should be addressed.

One point I think should be expanded is the validity of SST proxies in determining long term temperature reconstructions. A good paper would be the comparison of the SST proxies and tree ring proxies with the results through 1970. This would sidestep the 1970 ending period question and the error bars should be significantly lower for the sst proxies.

A good statistical evaluation comparing the skill of sea sediment versus tree ring proxies, I think would be amusing.

187. Judith Curry
Posted Nov 16, 2007 at 3:29 PM | Permalink

Lucia, Steven, Bender, yes I’ve caught the post on filtering and the other suggestions, thanks much

188. Craig Loehle
Posted Nov 16, 2007 at 3:37 PM | Permalink

re: 184 Bender. It is last para before discussion:
“A test of sensitivity to individual series was performed. Individual series were dropped and the mean recomputed, with all other steps the same. These eighteen series plotted in overlay (Fig. 2) show the same pattern as the original (Fig. 1). This plot demonstrates that no single series has undue influence on the result.”
That is jacknife.
“Random subsets of fourteen series were constructed and still show the same basic pattern (Fig. 3).”
That is bootstrap.

189. Jean S
Posted Nov 16, 2007 at 3:38 PM | Permalink

Craig: A simple thing you could do (would tell at least for me if there is possibly a filtering “bias” in the reconstruction):
1) Use simple first/second order interpolation of the original series to the annual data
2) calculate a reconstruction by taking the median of the yearly values
3) Plot 🙂

190. Craig Loehle
Posted Nov 16, 2007 at 3:40 PM | Permalink

Thanks to Jean S #183. Exactly.

191. steven mosher
Posted Nov 16, 2007 at 3:41 PM | Permalink

RE 156. Thanks Pat. However as JEG has pointed out CA regulars like me are not interested in criticizing
this paper.. so now I’m confused..

192. Posted Nov 16, 2007 at 3:42 PM | Permalink

Judy–
I could, by the way, explain the rule of thumb of “30”. It’s a rule of thumb, and so can be modified. The reasoning has to do with beta error. If you’d like other discussions I guess the place to do that is unthreaded.

Bender– thanks for mentioning the first name or Judy’s jaw might truly have dropped at the thought that “Dr. Liljegren” was here in comments. 🙂

193. IanH
Posted Nov 16, 2007 at 3:42 PM | Permalink

Several people seem to be asking correlation questions between the proxies. Have any of them read the paper, where not only is there an overlay of the resultant minus each of the series, but further an overlay of random 14 of 18 overlaid. Stop posting, start reading, I accept that there the report doesn’t include a whole load of stats, but frankly, I’d rather have it this way, present the data in a simple fashion, back it up by simple (to the lay man) exclusion of proxies then let the Mannians make fools of themselves trying to tear it apart. If only they would adopt the same approach.

194. Posted Nov 16, 2007 at 3:42 PM | Permalink

#152
JEG,
To what degree was your #143 review written independently of my #16? Thanks in advance.

almost entirely. started writing last night and was happy to see we had common points. I would argue that most of yours are “fatal”, though, but that is a subjective judgement.

#164
Even though I posted this above, people keep asking about validation stats. The temperature series were all derived from regressions of proxies against LOCAL temperature over recent periods in the original pubs. All of these have R2 stats etc. I did not compute a model or a regression, so it is not possible to compute goodness of fit. Cross-validation and RE and R2 are only relevant if you have a MODEL and I did not compute a regression or any model. Are there RE or crossvalidation stats or R2 on the GISS 126 year temperature history? Also, I did not do a formal hypothesis test, as this is not supported by the data.

There’s a good reason why people keep asking about it, Craig : while you may not realize it, you *are* using a statistical model called a multivariate regression. Indeed, each of the proxies was calibrated against temperature using such regression methods, usually linear, but sometimes non-linear (Mg/Ca ratios depend exponentially on seawater temperature, for instance). So by doing even a simple average, you are effectively using a statistical model, and are not exempt from the verification exercise.

It is quite ironical to be calling d18O “temperature” without considering how much temperature variance it describes, and downplaying the GISS NH temperature curve altogether. While the latter involves (minor) statistical assumptions, it is a compilation of physical *measurements*. Thermodynamics is not sedimentology. But to a statistician that may be all the same, who knows ?

For the error bars, I assume that either the reader knows about the problems with the various proxies or can go read my 17 citations.

How convenient ! That way we can just take your word for it and stop questioning the choice of proxies. Brilliant.

But: what is known about the various types of error is not readily converted into error bars (go ahead, tell me how to do it), so I did fig 2 and 3 as the best that can be done with this type of data.

Here’s how to do it, for example : http://www.image.ucar.edu/~boli/manuscripts/2007-LNA-TeA.pdf
If that is the best that *you* can do, then you lose every credibility as a challenger of the “Team”.

1970 to 1999 are not AWOL. The data only go to 1995 and 1980 is the last 30 year smooth that can be computed. Try reading the paper after you cool off.

OK OK, my bad. The late twentieth century just looks a little unusual. I acknowledge i had read this part a little quickly, but I still think you should pay closer attention to smoothing potentially non-stationary timeseries.
(warning : epileptics and people allergic to the name “Mann” should not open this link)

[…] At each point what I have is the mean of the 18 smoothed proxies. Thats all. I do not claim that it is a valid global mean and of course it is not. But that is all the data that existed as of 1 year ago in public archives that I could find. We will never have 1000 datasets to get a valid global 2000 year mean. I said that for these 18 points scattered across the globe, the MWP appears real.

Then isn’t it staggeringly misleading to call this a ‘global temperature reconstruction’ ? (did i misread, or is it the title of the article ?). The adjective ‘Global’ implies representativeness of an area-weighted average, which it is not. Now, it may turn out that your spatial sampling does a reasonably job at representing tropics, mid and high-latitudes , but it seems a little careless not to ensure it, and even more unforgivable no neglect mentioning it.

I would have no problem if the paper said : “Picking 18 series that obey a set of objective criteria, i find that on average they display a warmer than present MWP”. One can argue about the criteria, but at least the conclusion is falsifiable.

What you did is VERY different thing : you pick 18 timeseries on criteria that do not guarantee a proper spatial and temporal resolution of the temperature field. You smooth them using rudimentary methods, aggregate them together without any other form of consideration, and sell it to reader as a “global reconstruction”. Worse, you conclude that the “it would indeed seem to show the MWP to be warmer than the late 20th century” by 0.3 deg on average, implying that it is representative of a global average. Or did i misread ?

FYI, you can test that result for significance : i heard it was called a Z test. In truth, it would have to be a lot more sophisticated than that (cf Li et al 2007). But hey, if CA readers and participants are so much smarter than us dumb climatologist, they can do it ! Bring it on, my friend !
If, as you claim, ” formal hypothesis test, as this is not supported by the data”, then perhaps you are saying more than what your data warrants ; which is pretty much nothing. The bottom line is : if yours was a serious study, you would build upon the vast array of statistical techniques that have been developed for that in the past 9 years that elapsed since MBH98 (see the NAS report of a catalogue). Since you do not bother to do that, do not expect to be taken seriously.

If on the other hand, you are after a bona fide tree-ring-independent reconstruction, i’m sure you will find support in the climate community.

Re #167 : thanks for your support Judy, but you’ll find that i’m hard to scare.

I knew when i entered this debate that i would face Nobel laureates like steve mosher calling me “puppy” or even bird names. I knew some people who jump out of their chair at the mere mention of “denialist”. I knew people like Sam Urbinto would deflect comments from the actual question, and make other artful uses of ignoratio elenchi. As i said, in spite of all that junk, i still read CA (and i am obviously not alone) because when you want to know what happens, you don’t read party’s paper, you read the opposition’s. It is now up to this opposition to make a clear statement about the goal of this blog :”Climate Audit” or “Climate Trash-talk” ?

195. Pat Keating
Posted Nov 16, 2007 at 3:46 PM | Permalink

Craig

I would like to compliment you on your coolness under fire and professionalism. I know from personal experience how painful it can be to see one’s youngest ‘child’ criticized in harsh and/or ignorant ways.

Keep up the good work and the ‘stiff upper lip’.

196. Posted Nov 16, 2007 at 3:49 PM | Permalink

hmmm, please forgive the typos in my previous post. Ah, the heat of the battle !

Re #143: JEG, you did note, didnt you, that Steve McIntyre, in the header for this post stated:

Ill try to comment later but have some other obligations right now.

And so far as I can see, he hasnt yet turned his attention to Craigs paper.

Can I suggest that you might take that into account in your comments.

Yes, i did note that, and i find it very entertaining that when Caspar Amman is struggling with publication deadlines, it deserves a “Where’s Caspar ?” entire thread, but that when Steve McIntyre is busy, his army stands still to hear what he has to say because they can’t form a judgment by themselves.

Julien

197. MattN
Posted Nov 16, 2007 at 3:53 PM | Permalink

Error Bars: why?

From what I remember of MBH98, the error was greater than the observed change, which to me made it absolutely meaningless. Must we add levels of complexity with error ranges, confidence levels and correction factors? That’s just more ammo for controversy.

Can’t we just for once see some actual non-massaged data?

198. Mike
Posted Nov 16, 2007 at 3:54 PM | Permalink

JEG seems angry

199. Pat Keating
Posted Nov 16, 2007 at 3:57 PM | Permalink

JEG
I’m wondering, Julien, where I might find your equally picky and scathing comments regarding the work of Mann and other members of the Team. You have a nice turn of phrase, and would love to read more of your critiques, preferably in the context of the AGW acolytes’ work.

200. Spence_UK
Posted Nov 16, 2007 at 3:57 PM | Permalink

JEG,

I note you make a few valid comments – particularly the lack of confidence intervals (although I wouldn’t hold Mann’s attempts in MBH98 as a gold standard for this – poorly described, incorrect confidence intervals presented as valid are not an improvement over no confidence intervals).

With regard to proxy selection, calibration and dating, I would suggest that relying on others to achieve this is an entirely fair way of doing it. I would argue it reduces the opportunity for researcher bias to enter into the study. That said, I would personally like to see a definition for what justifies a proxy selection with sufficient accuracy to enable out-of-sample data to be added in the future, as more records become available. Practically, this probably needs some account of signal-to-noise (or confidence) of the original study to local temps, plus some ability to weight geographically to prevent well-studied areas becoming overweighted. I’m not claiming this study is a panacea in this regard, but it is an interesting and (I think) valid alternate approach.

– SMOOTHING : a running mean is essentially a multiplication by a gate function , which – as the author must be well aware of – amounts to a convolution with a sine cardinal in frequency domain. This introduces sidelobes that distort the signal, and would presumably mess up the edges of the timeseries. Oddly enough, the 1970-1999 period has gone AWOL. One would like to see other smoothing methods applied to remove that doubt.

This interests me. I am well aware of the preference for climate studies to want to run their reconstructions right up to the end point after smoothing. But why would you necessarily want to do this? We’re generating 2000 year record, is a loss of 15 years at either end a big deal? “Clever” end-point processing clearly involves either some form of extrapolation or increase in uncertainty (the uncertainty, I might add, is rarely properly accounted for). There is a valid reason to do this as an interim step (to prevent your data shrinking away), but there is really no valid reason to do it for presentational purposes. The running mean has pretty grotty spectral qualities, agreed, but it is unbiased, it has the benefit that it is about as short a filter you can get in the time domain for a given amoount of smoothing, requires no assumptions about end point handling / creates no end point issues if you simply truncate the series by half of the filter width at both ends. Comparatively, the other methods inevitably impose researcher assumptions into the study, creating an opportunity for researcher bias to influence the results (the end-point assumptions).

Finally, on your criticism on the effect of sinc function spectral leakage on the results, you may or may not be aware that Mann and Jones 2003 includes filtering of the MBH PC1 and a Jacoby series. The filtering applied is an interim result and the end points are retained. Guess what? Yep, the sinc function is there, clear as day, spectral leakage, an artefact of the processing. Perhaps you might want to have a word with Mann about what you have regarded here as a serious error? Note: I’m not arguing that the presence of the sinc function in the spectrum is a big problem, I’m just curious that you think it is, how that applies to MJ03; I’m happy to explore the point in more detail, especially as MJ03 actually use the end-points in their analysis.

201. bender
Posted Nov 16, 2007 at 3:57 PM | Permalink

Re #188
Ok, then, I did not miss anything; your methods are located in your results, and are not identified by name. The point remains: ‘sameness of pattern’, as you attempt to infer, needs to be tested using a formal significance test. Just eyeballing it is what North does. (Oh no, my bad, that’s “winging it”.) A jackknife or bootstrap as you define it gets you only halfway there.

202. Posted Nov 16, 2007 at 4:01 PM | Permalink

Yeah, JEG’s angry. BTW, he has not answered my question, is the universe static?

203. Craig Loehle
Posted Nov 16, 2007 at 4:06 PM | Permalink

Re: 194 JEG. Thanks for the useful ref. In Li et al that you referred me to is the following quote:
“Following a different concept, Esper et al. (2002) and
Cook et al. (2004) provided bootstrap confidence intervals for
low frequency temperature by resampling the tree ring chronology
sites.” So your friends have used the bootstrap also. While Li et al is very nice and fancy, they assume that the tree rings are measured without error (false), that the NH temp target is without error (false) and that the linear model assumption is valid for tree rings (see extensive debate about that here on CA). In my case, the studies I used have estimation error for the proxy at each sample which is often unknown or not stated. In addition, my study has series with gaps (not annual) and with dating error for each sample. In spite of this, I think doing a study without treerings has value because it shows what geologists had been saying for years (and was in the first IPCC report) that the MWP did exist.

204. Posted Nov 16, 2007 at 4:09 PM | Permalink

Craig:

205. trevor
Posted Nov 16, 2007 at 4:11 PM | Permalink

Re #196: JEG, the reason that I pointed that out is that so far as I can see, so far this thread has been entirely un-moderated. And, as I am sure you appreciate, the comments of the many posters are just that. Until Steve enters the fray, I suggest that you not take comments here as representing his (or for that matter CA’s) position on Craig’s paper.

206. Spence_UK
Posted Nov 16, 2007 at 4:11 PM | Permalink

Re #200

Did I write Mann and Jone 2003 there? Oops! Where I wrote Mann and Jones 03, replace with MBH99 CO2 correction. Mae culpa.

207. Pat Keating
Posted Nov 16, 2007 at 4:13 PM | Permalink

Craig

shows….that the MWP did exist.

That is what makes the Mannikins so angry……

208. Dave Dardinger
Posted Nov 16, 2007 at 4:15 PM | Permalink

re: #143 JEG,

You did notice that your posting was comment #143 which had been posted after less than 24hrs, didn’t you? And while there were some ataboys, there were a number of very pointed questions aimed at Dr. Loehle. There really wasn’t any call for a remark from you like,

Its hard enough sifting through the comments of ignorant global-warming-denialists on this site

Of course I also agree that some of our allies here leave a bit to be desired at times, but I’d hope you’ve noticed that you have similar problems. Do you perhaps have a sample post at RC which illustrates how you folks take on people who generally agree with you? We’re always anxious to learn.

209. John F. Pittman
Posted Nov 16, 2007 at 4:15 PM | Permalink

SOD #154 The source you quoted, emphasis mine:
http://www.wsl.ch/staff/jan.esper/publications/Buentgen_2005_CD.pdf

A new larch/pine composite chronology is presented, providing evidence of Alpine summer temperature variations back to 951 AD. The record indicates warmer conditions at the beginning of the past millennium, during the putative Medieval Warm Period, followed by an extended period of cooler conditions (the Little Ice Age) and recent warming since about the 1820s. According to this regional analysis, the most recent decade is the warmest period over the past millennium. However, the new Alpine reconstruction is particularly insecure during these recent yearsas well as at the beginning of the last millenniumwhere sample replication is low (e.g., average replication during the 19982002 period is 51 larch samples). Long-term, multicentennial trends and higher-frequency, inter-decadal variations fit quite closely with variations retained in large-scale reconstructions, indicating the relevance of this new record and the Alps to large-scale studies of global climate change. A comparison with other regional temperature reconstructions, nevertheless, demonstrates that the long-term trend and absolute amplitude of temperature variations is not understood. We intend to study this discrepancy more closely by developing well replicated records of maximum density of both larch and pine species.

210. DocMartyn
Posted Nov 16, 2007 at 4:15 PM | Permalink

” bender says:
November 16th, 2007 at 8:53 am

Let us suppose for a moment that Loehles MWP is correct. Let us suppose further that the Anasazi people in the SW US did indeed go into decline as a result of a series of MWP megadroughts. What do you think bristlecone pine ring widths would look like under those circumstances, given they grow in a subalpine desert where water is the essence of life? Fat? Or narrow? Would this be consistent or inconsistent with the Sheep Mtn bcp update? Is it possible that Loehles data and Ababnehs data are wholly consistent?”

I think you are asking exactly the wrong question. Indeed, the point you miss is what are you looking at in the tree ring data; survivors. Although a single Bristlecone Pine can have a 2,435-year tree lifespan, they rarely live over 1,500 years. The one’s that do have survived extremes of heat, cold and water stress.
the living trees that are sampled MAY live in places where due to some querk, are shielded from extremes of temperature/water stress.

211. bender
Posted Nov 16, 2007 at 4:18 PM | Permalink

JEG et al troll for research ideas at CA but then don’t cite CA in their papers?! Shame.

212. JS
Posted Nov 16, 2007 at 4:20 PM | Permalink

I reiterate my suggestion from #22 to look at a PC version of the series. This is a way of checking robustness as well as being informative in its own right.

PC is atheoretical as it does not impose any interpretation other than a mathematical one on the data. Nonetheless, it should serve to illuminate the implicit assumption underlying your ‘reconstruction’. Because you have quite a strong implicit assumption underlying the validity of a straight average of the data.

Averaging assumes that there is a common signal in each series and then random noise added to them. If there is any other quality to the data then averaging will lead to biases in the result. Averaging works best for more or less homogenous populations (e.g. the height of white males). However, your proxies are not obviously homogenous in the way they capture any temperature signal. They are from different processes and are from different locations around the globe. Yes, they have been calibrated to local temperature, but there are still idiosyncratic factors there.

I should note that PC is just a tool. It can be used well and it can be used badly. I would encourage you to consider if it can be used well in this case.

213. bender
Posted Nov 16, 2007 at 4:20 PM | Permalink

Re: Li et al. 2007. JEG, I thought you guys had ‘moved on’?

214. Craig Loehle
Posted Nov 16, 2007 at 4:20 PM | Permalink

I have been accused of exaggerating my claims. The last sentence in my paper is “It must be emphasized, of course, that this result is based on limited data.”

Bender would like a formal significance test. How do we test for “the MWP existed (or didn’t)”? I was trying to show qualitatively that the MWP is plausible if you don’t use tree rings, and I think this graph shows that. I did not feel the data supported formal hypothesis tests so I did not do them.

JEG: check out how bender is twisting my arm without being angry, without insulting me. very professional. try it.

215. Posted Nov 16, 2007 at 4:21 PM | Permalink

sorry sod 175, unclear on what you mean. If you mean by data point the values in fig. 1, they are posted on my web site (see fig 1 caption). The number of data points where? It is 18 series in general at each time, but not all series cover the time uniformly (some have gaps). You want a plot of how many series at each time? Probably over 15 at any given time point. Using bold letters does not make your question more clear, that is just shouting.

no.

you claim to be doing a 2000 years global temperature reconstruction, but you are “smoothing” out the important part.

if i did a 2000 year of computer technology analysis, using your methodology and ending around 1960, i might end up with the conclusion that some medieval computing machine was the high point of achievement!

the misrepresentation at the end is already quite bad, by using 1995 as last year. it gets worse by averaging it to 1980.
but if a significant number of your proxies have their last temperature data BEFORE 1995 (and i doubt that Conroy Lake pollen (Gajewski,
1988)
includes 1995 data..), the “smoothing” gets even worse.

i do not believe, that you have a foundation, to make observations like:

Even keeping in mind that Figure 1 shows 30-year running means, it
would indeed seem to show the MWP to be warmer than the late 20th century.

216. Dave B
Posted Nov 16, 2007 at 4:23 PM | Permalink

As a relative layperson, I’d like to point out how refreshing it is to see a proxy study with clear inclusion criteria (2000 year, 20 points) and exclusion criteria (tree rings). The consistent unwillingness of the “Team” to assess and admit what happens to a proxy analysis in the absense of Cherry-picked bristlecones arouses suspicion.

217. trevor
Posted Nov 16, 2007 at 4:24 PM | Permalink

Guys, guys, guys. Until Steve returns and can moderate, can we please all keep civil to each other, and maintain the decorum that CA deserves.

Posted Nov 16, 2007 at 4:25 PM | Permalink

This is so cool …La Sorbonne en web ….

219. Posted Nov 16, 2007 at 4:25 PM | Permalink

Re #$202 It’s unfair to say i’m angry. It’s the pot calling the kettle black… Most CA posts have a distinctly derogatory tone against 95% of the climate community, so i thought i would fit 😉 But fret not : i’m not even angry *yet*. However, i might get there if the real questions on this reconstruction are not honestly and earnestly addressed. Forget about smoothing practices. Forget about bootstrap vs jacknife . I should have kept it to one simple point. Why does the title claim “A 2000-YEAR GLOBAL TEMPERATURE RECONSTRUCTION”. while the author admits “I do not claim it is a valid global mean and of course it is not” ? And shouldn’t you need a valid reconstruction of the global mean before you can conclude ” it would indeed seem to show the MWP to be warmer than the late 20th century” ? That’s it. Let’s keep it simple. That’s all i really care about. Magnanimity is not a very high currency on Climate Audit, but i’ve shown myself nasty enough today that i should make a little effort… Craig ? combatively yours, Julien PS : BTW, in case anyone is interested : i don’t believe a global or hemispheric mean to be of much interest on a dynamical point of view, and we should instead focus on reconstructing variables with a more physical meaning. Like NINO3… speaking of which : enough playtime, i must get back to my real work. 220. bender Posted Nov 16, 2007 at 4:25 PM | Permalink Doc Martyn, You are too funny. Please check this post. Have a great weekend. 221. Posted Nov 16, 2007 at 4:29 PM | Permalink Re #202 It’s unfair to say i’m angry. It’s the pot calling the kettle black… Most CA posts have a distinctly derogatory tone against 95% of the climate community, so i thought i would fit by being a little rude 😉 Apologies if anyone got offended. But fret not : i’m not even angry *yet*. However, i might get there if the real questions on this reconstruction are not honestly and earnestly addressed, because it is highly upsetting to a scientist when low-grade statistics are sold as climate science. But let’s forget about smoothing practices. Forget about bootstrap vs jacknife . Forget about errorbars. I should have kept it to one simple point. Why does the title claim “A 2000-YEAR GLOBAL TEMPERATURE RECONSTRUCTION”. while the author admits “I do not claim it is a valid global mean and of course it is not” ? And shouldn’t you need a valid reconstruction of the global mean before you can conclude ” it would indeed seem to show the MWP to be warmer than the late 20th century” ? That’s it. Let’s keep it simple. That’s all i really care about. Magnanimity is not a very high currency on Climate Audit, but i’ve shown myself nasty enough today that i should make a little effort… Craig ? combatively yours, Julien PS : BTW, in case anyone is interested : i don’t believe a global or hemispheric mean to be of much interest on a dynamical point of view, and we should instead focus on reconstructing variables with a more physical meaning. Like NINO3… speaking of which : enough playtime, i must get back to my real work. 222. bender Posted Nov 16, 2007 at 4:33 PM | Permalink JEG, could you redo Li et al. (2007) analysis without bcp/foxtails & other drought-limited species? 223. Craig Loehle Posted Nov 16, 2007 at 4:37 PM | Permalink JEG: let me try to be more clear. It is a reconstruction. The data are global, but limited to 18 sites. It is far from perfect but it is a start. Your colleagues have done NH reconstructions with no more sites than this (or fewer) –though more trees. Is it not global just because it is not perfect?–you can have your own opinion. Also, the scathing criticism for certain work on this site is the result of invalid results not being acknowledged, or people hiding their data. I, however, do not make such comments. It is not professional. Hans: I will try to get the links to the raw data when I can, but JEG is keeping me pretty busy. 224. Bernie Posted Nov 16, 2007 at 4:44 PM | Permalink Most of your ideas sound okay to me and well worth considering. Here is how one CA’er thinks about what you said. Relationship of each proxy to *local* temperature is not even discussed Agreed. It would be helpful to provide a synopsis of the +/- of the series as a temperature proxy Error bars on the proxies Agreed. These would help understand how much range there is in the curve and they should be in the table that you requested above. However, isnt the sensitivity analysis itself is a form of addressing this issue? Borehole d180 temperature is a climate neologism . Not sure I understand this  unless it is simply a dig. Relationship to global temperature Agree but you are asking for something that I do not recall seeing elsewhere. Moreover, when the sample is so small given the overall population then weighting these things is false precision to say the least. A meagre sample is a meagre sample. TimingPerhaps this is a separate paper, but seems to be an additional point to the one being focused on here. SmoothingSeems like this can be applied to all proxy studies. The extending of the proxies to take in the last few years is a great idea. Validation R2  Good idea but the sensitivity analysis again does this at least at visual level. Overall, it seems that you have captured and applied many of the issues that Steve and others wrestle with here. I suspect Steve will be as pointed as you, but probably with a slightly more constructive tone. 225. Sam Urbinto Posted Nov 16, 2007 at 4:48 PM | Permalink JEG, there’s a lot on here that Steve would have snipped, moved or deleted if he were moderating it. And not everyone’s going to agree with you, or each other, or Steve, and they’re certainly not speaking for Steve, no matter who they are. I doubt most of the views here would be treated well over at Real Climate, or in other words, they wouldn’t get posted at all. At least here we’re open to all ideas. I’m not trying to do anything of the sort, deflect comments from the actual question. I told you I am not qualified to comment on the paper, and thought since you were here you might like to explain some things to us. I’m sure a number of your criticisms are valid, but I’ll leave it to folks like Spencer and Hans and Jean to go over things in their fields and wait for Steve to go over it in his. You know, the multidisciplinary approch to a multidisciplinary science. I appreciate you coming over and joining the debate. Your criticisms are appreciated (although perhaps not in the way they’re phrased, but like mosher said, it happens.) But give me a break. The thing just came out yesterday for crying out loud. You don’t have a valid comparison about a time period involving months. Or data not updated for 25 years or unarchived for 20. And regardless of the issues in this paper, it hardly makes sense to complain about them if the same techniques are used with the tree-ring studies. Nobody’s calling anyone dumb here, so that’s an interesting little trick on your part. Some here are more intelligent, and others less intelligent at what they do. But it doesn’t help determine what’s going on when the methods are hidden, the code unavailable, the raw data not archived, and all the obfuscatory hand-waving dodging and weaving going on. There’s no excuse for it and it’s frustrating. I think given the level of frustration, we are being very civil, I doubt the opposite would be true in general. I’m not specifying anyone, just saying that in general, it seems to be an overall pattern. Oh, and it might interest you to know I agree with the basic conclusions of the IPCC. I think most people here do too, but that we ask questions about things, and have various issues and disagreements with some of the conclusions. Do you beleive that if we question anything about anything about the details that automatically makes somebody a denier? If so, how curious. Does wanting to audit statistics to see what’s happening automatically make somebody a denier? If I was out of line asking you what you thought about land use changes, particulates and 2x co2 = 2.5 C I appologize. I question the appropriateness and meaning of CO2 = +temp but I don’t know it’s not appropriate or not meaningful. It could be true. I question what a “global mean anomaly” means, but it’s certainly there and could be very meaningful. Can I say “I don’t know” and then ask for more information? 226. Will J. Richardson Posted Nov 16, 2007 at 4:56 PM | Permalink Dear Dr. Emile-Gaey, Since you are presently working with Dr. Mann on a paper, could you please ask him to provide some assistance in resolving the issues presented on this Climate Audit thread? Thank you. 227. Will J. Richardson Posted Nov 16, 2007 at 4:59 PM | Permalink Re: 226 The reference should be to 228. Steve McIntyre Posted Nov 16, 2007 at 5:00 PM | Permalink I’m on a little holiday trip with my wife and only have time to check in briefly today and don’t have time to respond to many interesting points. Our “apple picking reconstruction” to the NAS panel is here . Rosanne D’Arrigo told the NAS panel that you have to pick cherries to make cherry pie; our point as that if you picked apples you could make apple pie. JEG raised review points that would surely apply to virtually every multiproxy reconstruction. JEG observ$se:

– Relationship of each proxy to *local* temperature is not even discussed. We are just shoved a list of references (hey Craig , have you heard of tables ? They are a great means that scientists use to convey information clearly). How is it that tree-rings are seen as the penultimate antichrist but that, to take but one example, d18O of speleothem calcite (e.g. Holmgren et al., 1999) is a flawless paleothermometer ? Shouldnt one discuss one by one, and with great care, the pros and cons of each proxy as a temperature recorder ? d180 in forams is a notoriously flawed temperature proxy, is being replaced by Mg/Ca where possible, and one can only surmise why the Keigwin[1996] series is here.. Is it just a form of screening for proxies with a low hockey-stick index (in McIntyre parlance) ?

I agree that a detailed list of exact data sources should be a prerequisite of this sort of calculation. Having said that, Hegerl et al Nature 2006 for example contains no information on the proxy provenance. As an IPCC reviewer (where the paper was cited), I requested information on the series on the series used, which the authors then refuse to provide and IPCC did not require them to provide. Partial information was provided in a later publication J Clim), but after nearly a year and repeated emails, I have still been unable to determine the identity of several series versions. Crowley at one point said that he had a hard drive failure but that was nearly a year ago.

JEG, I am unaware of the type of discussion that you request in any of the usual papers. Where is the calibration to local temperature (for example) of the Arabian Sea G Bulloides series used in Moberg and Juckes? Why is this a defect in Loehle and not for Moberg?

JEG, you say:

Say what you want about MBH98 : in spite of its many flaws, it made extremely explicit attempts at estimating error bars. One would expect this work to have paid attention to past work and up the ante where it can.

Perhaps you can explain to us how MBH99 confidence intervals are calculated. We’ve tried pretty hard to figure it out and haven’t succeeded. Requests both to Mann and to theNAS panel to clarify this have gone unanswered. See http://www.climateaudit.org/?p=647 http://www.climateaudit.org/?p=648

Merely using 2-sigma errors in an overfitted calibration period (as in MBH98 but not MBH99) is not an improvement over no calculation. The calculation is incorrect and very misleading. The verification r2 of Mann’s reconstruction is more or less zero and CIs calculated from the verification period would be approximately the same as natural variability – whatever that is (and it’s not an easy question to answer) See illustrations of overfitting through Mannian-Ammannian inverse regression here http://www.climateaudit.org/?p=949

I agree that “borehole dO18” is meaningless. Dahl-Jensen is a borehole reconstruction.

You cite Hughes and Diaz 1994 as an authority. Without going into detail, the proxies selected in Hughes and Diaz are very problematic and I do not think that you can draw any conclusions from this study. Even Jan Esper in his IPCC review comments recommended that it not be cited.

229. jae
Posted Nov 16, 2007 at 5:11 PM | Permalink

JEG: Do you know of any “reconstructions” that fit your expectations?

230. Posted Nov 16, 2007 at 5:21 PM | Permalink

Bernie says :

Error bars on the proxies
Agreed. These would help understand how much range there is in the curve and they should be in the table that you requested above. However, isnt the sensitivity analysis itself is a form of addressing this issue?

The sensivity analysis only addresses “red-herring effects” : how much one given series influences the reconstruction as a whole. By construction, since they have equal weights, it’s only 1/18th of the result, so it can’t do much unless it has a vastly different value.
It is a very useful analysis in itself, but gives a false sense of security in regards to the accuracy of the mean. Imagine all of the 18 proxies were accurate within +/2.5 degrees. Then what to say of a 0.5 degree change ?
I agree that error bars are not easy to truthfully establish, but say what you will about MBH98 ; they tried, and that’s a BIG difference. Sure, in an “ideal world” (in Loehle parlance), all the proxy 2-\sigma errors would be know perfectly over the past 2000 years. It is not the case, but that is a poor excuse for ignoring the issue altogether.

Borehole d180 temperature is a climate neologism .
Not sure I understand this  unless it is simply a dig.

OK, let me try again. There is no such thing as a “Borehole d180 temperature” (methods section, L4). Borehole temperatures are one direct (although blurred) measurement of past temperature down the ice cap. d18O is an isotope ratio that has a complex (though interpretable) relationship to temperature in the adjacent region. “Borehole d180 temperature” = nonsense.

Relationship to global temperature Agree but you are asking for something that I do not recall seeing elsewhere.

Hmmmm… let me see : MBH98, MBH99, Esper et al 2002,Rutherford et al 05, Hegerl et al 2006, etc. etc etc.

The point is : either you care about LOCAL temperatures and you use something known as a Composite Plus Scale approach. Or you only care about the ability of a proxy series to record *some* climate information via teleconnections : that is the heart of climate-field reconstruction techniques, like MBH98 or the more sophisticated RegEM-based versions. (Rob, would you agree with this dichotomy ?)

In either case you explicitly account for how proxies describe variance in the mean temperature ; either by regressing them against the mean, or against local temperature (and then average them), or against a subset of principal components that describe the large-scale features of the temperature field, then use that to reconstruct this linear subspace of the T field and then average it globally (the Mannian approach).

No such thing is done here, and it should. Again, it comes down to whether Craig wants to convince scientists that his reconstruction says anything about climate, or whether he only wants to cater to a crowd (which is some, but crucially not ALL of the CA readership, thank goodness) that goes off in loud cheers anytime someone throws dirt at Mann, Hansen, Al Gore, and others.

Validation R2  Good idea but the sensitivity analysis again does this at least at visual level.

If a visual fit is enough for validattion, then why are there so many complaints about Mann et al not dutifully using the Rsquared statistic for validation ?

Again, i’m simply making the point that if you have high standards for “Team”, then you must have high standards for everyone.

Overall, it seems that you have captured and applied many of the issues that Steve and others wrestle with here. I suspect Steve will be as pointed as you, but probably with a slightly more constructive tone.

Thank you. But i think I’m damn constructive ! Look at how much progress we’ve made so far ! 😉

I will surely read Steve’s insightful analysis with much interest.

Craig Loehle says:
“Hans: I will try to get the links to the raw data when I can, but JEG is keeping me pretty busy.”

I love it !!! Now it’s my fault ! “The reconstruction is meaningless and i don’t make raw data available on time, but blame it on the Frenchie !”
Well, perhaps now you understand what it is to be a climate scientist, have many obligations for your job, and also have to satisfy the demands of CA’s inquisitive minds. Overall i think everyone will learn valuable lessons here.
I certainly am.
BTW, thanks to everyone who is actively engaging in the scientific part of this discussion ; it is refreshing.

Bender says :
“JEG, could you redo Li et al. (2007) analysis without bcp/foxtails & other drought-limited species?”

Why don’t you do it yourself and tell me the result ? 😉 If it’s worthwhile i’ll listen.

Wishing you all a pleasant week-end… see you monday.

Sorry again if anyone got offended at my tone but it did push just the buttons i wanted to push, and perhaps now we can talk about science.

231. steven mosher
Posted Nov 16, 2007 at 5:23 PM | Permalink

RE 194: Funny Puppy JulieAnn

JulieAnne: Everybody knows I called you a puppy. yet you pee yourself and make a whimpering link
to it, proving my point. GO FETCH!

Bender posts the evening of the 15th
at 7pm. The intrepid puppy posts the next day many hours later. mirrors everything bender,a CA regular, has to
say. Claims that CA folks wont criticize their own, hopes Bender won’t recognize the plagarism.
when Bender calls her out she claims she worked all night on it.

Silly puppy.

232. John Norris
Posted Nov 16, 2007 at 5:25 PM | Permalink

Had I known JEG was teaching a hockey stick class right here in Atlanta, I could have saved some significant CA bandwidth.

http://eas8001.eas.gatech.edu/syllabus.htm

233. Spence_UK
Posted Nov 16, 2007 at 5:26 PM | Permalink

JEG said:

OK OK, my bad. The late twentieth century just looks a little unusual. I acknowledge i had read this part a little quickly, but I still think you should pay closer attention to smoothing potentially non-stationary timeseries.
(warning : epileptics and people allergic to the name Mann should not open this link)

Thanks, we are well aware of the problems associated with this method, they are discussed here. No allergies, not sure what your point about epileptics is, but just plain old boring analysis; and, funnily enough, Mann’s low pass filtering has serious problems. (The x and y reflections, in particular, pin the end point – a gross extrapolation assumption, with obvious and unpleasant consequences, and high-order butterworth filters implicitly cause overshoot… hmm, why would a climate scientist want overshoot in their series?)

234. Michael Jankowski
Posted Nov 16, 2007 at 5:27 PM | Permalink

sod,

this paper has tree ring data up to 2003 and produces a hockey stick:
http://www.wsl.ch/staff/jan.esper/publications/Buentgen_2005_CD.pdf

My 10-minute glance, since you’ve posted this paper many times and deserve some sort of response.

The only thing close to hockey stick I see may largely occur due to the “padding” from 1980-onward. One would have to see the raw data.

I noticed the pine series shows no hockey stick in recent years, despite the author noting that the pine picked-up the MWP better than the larch ones (148, 4.1, 2nd para). And the pine series does not seem to be responding to the supposedly anomalous 20th century warmth, even though it seemed more sensitive in the past to temp changes than the larch series. So I’m curious if something else possibly (CO2 fertilization) might be driving the two strongest larch series (or larch series in general?).

I noticed the author in multiple locations (third para of 4.1, second para of 4.3, last para overall) notes the “insecurity” of the reconstruction near the endpoint. With the flat pine series ending in ’97, a relatively flat larch series ending in ’94, and one other series ending in 1915 that would’ve contributed who-knows-what to recent decades, that’s another caveat. The recent decades are dominated by the two larch series which show explosive growth, without the dampending one would expect to see if the other series continued.

But maybe that’s all getting nit-picky. After all, there are instrumental records in the area which show common trends, correct? Good. So what you may have in the end is tree proxies which suggest the summer temps in the alps are higher than they’ve been in over 1,000 yrs. The thing is, there are any number of regional proxies which suggest a MWP warmer than today. These are dismissed as “regional phenomenon.” So maybe that card has to be played here, too?

235. Steve McIntyre
Posted Nov 16, 2007 at 5:28 PM | Permalink

I love it !!! Now its my fault ! The reconstruction is meaningless and i dont make raw data available on time, but blame it on the Frenchie !

JEG, please stop this sort of immature exchange. I agree that Craig Loehle should have had this information available as part of the SI to the publication, but I also expect that he will respond promptly to the request.

236. Posted Nov 16, 2007 at 5:47 PM | Permalink

Evidently, it did hurt them… 😉

237. Geoff Sherrington
Posted Nov 16, 2007 at 5:50 PM | Permalink

Re #57 Douglas Foss

As in all of this reconstructed data, would you agree with the suggestion that a high sampling frequency (as in modern times) has a better chance of including the larger excursions (short-term though they may be), while sparse, older data tend to be more levelled because the short extreme events have less chance of detection? If you take your body temperature once a year, don’t you tend to miss the one-day passing fever?

238. steven mosher
Posted Nov 16, 2007 at 6:08 PM | Permalink

RE 235.

That’s a cool idea. Upon request which writer JEG or Dr. Loehlm will post the data and methods

Dr. Loehlm will post his and JEG will post hers.

Maybe this one?

Or this one:

http://digitalcommons.libraries.columbia.edu/dissertations/AAI3249076/

She can choose which ever. I think Ssadlov would love some of the ENSO stuff.

239. Posted Nov 16, 2007 at 6:18 PM | Permalink

Steven Mosher… I apologize, it’s not a criticism… you know me. Just that it is not Loehlm, but Loehl, and Dr. Julien is “he”, not she. His name is french thus the confusion. 🙂

240. Andrey Levin
Posted Nov 16, 2007 at 6:30 PM | Permalink

As a layman reader of CA, I would like to thank Dr. Loehle for this clear and straightforward paper. It IS very impressive.

No doubts it will get this kind of reception from the establishment:

BTW, it would be interesting to hear opinion of Dr. Loehle on the question of Steve Sadlov what the real sweet spot for CO2 concentration actually is.

Re#59, Rob Wilson:

Thanks for inclusion of NH instrumental reconstruction in the graph. Once again it suggests that last 30 years instrumental global temperature reconstruction is a junk.

241. Posted Nov 17, 2007 at 1:50 AM | Permalink

Please, zoom the image up to 150 so you can appretiate the details. I ploted the raw data of SI Reconstruction in red.

242. Posted Nov 17, 2007 at 1:54 AM | Permalink

“appreciate” and “plotted”, I’m really sleepy… sorry.

243. Ed Snack
Posted Nov 17, 2007 at 1:55 AM | Permalink

JEG, in your undoubted ignorance you post “If a visual fit is enough for validattion (sic), then why are there so many complaints about Mann et al not dutifully using the Rsquared statistic for validation ?” I do wonder about your actual degree of claimed knowledge. MBH98 did of course compute R2 for validation. Before you dispute this please examine the code released by Mann wherein R2 is calculated. No, what we really want to know is why, having calculated R2, Mann only reports it when it supports his faux conclusions, not when it doesn’t. There is a word most people would use for that, see if you can imagine what it is, an exercise for you if you like.

244. Louis Hissink
Posted Nov 17, 2007 at 1:56 AM | Permalink

General comment on “peer review” – in the New Concepts in Global Tectonics Newsletter, No 44 Oct 2007

18 New Concepts in Global Tectonics Newsletter, no. 44, September, 2007
PRECURSORY LUMINOUS PHENOMENA USED FOR EARTHQUAKE PREDICTION 
THE TARO VALLEY, NORTHWESTERN APENNINES, ITALY
Valentino STRASER
94, Località Casarola  43040 Terenzo PR, Italy
fifurnio@tiscali.it

Editors note: After due consideration, and some negative peer reviews, we have decided to publish the following paper because it opens up for discussion a topic of considerable sociological and political importance as well as one with significant geological ramifications. Obviously more research is needed on this matter before definite conclusions can be drawn with any confidence, but the paper gives suggestions as to how a start might be made in this direction. We look forward to readers reactions.

ABSTRACT
Earthquakes do not occur randomly. They are the manifestation of natural phenomena ruled by definite physical laws. Prevention of seismic risk lies in the study and interpretation of areas under dynamic evolution. Earthquakes are associated with energetic manifestations that are not only mechanical, but also electric, electromagnetic and electrochemical in nature. Comparison of their recorded data as well as on-field research and interviews has enabled the building of a specific model to establish the frequency of events that might act as a guide to a more tailored definition of seismic risk for any area in the world. The results of this study refer to the Taro River Valley geo-structural complex and highlight a close link among the studied geophysical events, clearly showing them to be enforced by a ‘Code’. Interpreting such a Code allowed the successful forecast of superficial and low-average magnitude seismic events from 2005 to 2007. Forecasts were made several weeks in advance, and included the indication of the epicentre zone and the time lapse of the event.

So if the paper is scientifically sound, we in the renegade heretical camp of plate tectonic denialists, do make sure things get published. I suspect Craig’s paper would have been given the all clear flag in NCGT as well.

245. Posted Nov 17, 2007 at 2:08 AM | Permalink

JEG,

I agree that error bars are not easy to truthfully establish, but say what you will about MBH98 ; they tried, and thats a BIG difference. Sure, in an ideal world (in Loehle parlance), all the proxy 2-\sigma errors would be know perfectly over the past 2000 years. It is not the case, but that is a poor excuse for ignoring the issue altogether.

MBH98 applied a classical estimator to multivariate calibration problem, but they forgot to read relevant statistical literature (and added many incorrect steps along the way). 2X std of calibration residuals works only in the case of perfect calibration. It is a high school level solution.

246. JS
Posted Nov 17, 2007 at 2:14 AM | Permalink

Another comment:

Why are you smoothing the data at all? Particularly when you are taking an average which will tend to cancel out the high-frequency idiosyncratic noise anyway.

Smoothing is just one more step that introduces possible distortions into the results. By all means smooth the final result for expositional and presentational purposes. But there is no apparent need to smooth the individual series prior to the final result. Regardless, I think you need to be clear why you are smoothing and what you hope to accomplish by doing so. You then need to balance what you hope to gain by the smoothing (I would argue not much) against the costs in terms of possible artifacts and general confusion about what is going on (see, for example, all the discussion about ending in 1980).

247. Bob Meyer
Posted Nov 17, 2007 at 3:31 AM | Permalink

Re 246

JS

If I’m not mistaken, a moving average is a linear transformation. If so, then you get the same answer whether you filter first and then take the average, or average first and then filter. The spurious components generated by the filter for each data set will be correlated with each other to the same extent as the actual signals are correlated so the final result should be independent of the sequence of filtering and averaging.

I agree with a previous post that several different kinds of filters should be used on the data to determine the existence of significant spurious signals.

248. Geoff Sherrington
Posted Nov 17, 2007 at 4:24 AM | Permalink

Re # 194 JEG

(Mg/Ca ratios depend exponentially on seawater temperature, for instance).

Scientifically, this is an inexact statement. The movement of calcium (in whatever form) and magnesium (ditto) in water does not of necessity follow the same pattern of movement of temperature. It is not a sufficient test to sample a dead shell population and match Ca/Mg with temperature. It is required as well to show that any association persisted before the measurements and ideally, persists after the measurements.

I know of no inherent reason why a Ca/Mg ratio comprehends an exponential function. I do suspect that some methematicians or modellers sometimes jump to conclude that a non-linear response must by default be exponential, because it is the next most convenient of the relationship curves; but this objection is secondary to the danger of relating Ca/Mg to temperature – especially when each can exist in water in small biologic forms as well as inorganic ions and other forms of likely different behaviour re their uptake into shells.

So, JEG, where are your error calculations for the relation between Ca/Mg and temperature in your dogmatic assertion? What coverage of the globe has been tested with this assertion? etc etc. If you seek to criticise using examples, your examples must also withstand similar examination.

And yes, I did note that one of the many series cited was 3) Chesapeake Bay Mg/Ca (Cronin et al., 2003). I have read it.

Posted Nov 17, 2007 at 4:32 AM | Permalink

Thank you Dr Loehle for publishing your reconstruction of “global” temperatures from non treering proxies.
Not one post has disagreed with the obvious statement that there was a MWP and a LIA, so I think that there is consensus that both did actually happen. I don’t think there is much point in harping if the MWP temperature was marginly higher or lower than the present.
What is obvious from the charts that there can be very dramatic and quick changes (relatively) in temperatures both negative and positive which cannot be explained by GHG. If they cannot be explained by GHG what has caused these reversals.
Yes, the Lia and the Maunder Minimum coincided but what about the MWP?
What explanation is there for the steep reversals in temperature?

250. Posted Nov 17, 2007 at 4:54 AM | Permalink

#88

the scaling makes little difference to your series except depressing the cooler period (e.g. the LIA) a little. The MWP levels are the same.

And this kind of distortion of (possible) signal doesnt bother you?

251. Paul
Posted Nov 17, 2007 at 5:28 AM | Permalink

When JEG calms hisrhetoric he has some valid points (as picked up by Bender earlier). However, I find some irrelevant at best. The overall thrust appears to be a complaint that Craig has mirrored the standard team approach (call it global calibration, or regrssion of regional/local/sourced PC/proxies against estimates of global mean temp.).

I can’t buy into that. This represents a truly independent (the first such???) method to addressing the same essential question:

What has been the variability of global mean temp. on a millenial scale?

I think tying down the local proxy calibration issues (i.e. to local temp) as well as addressignt he statistical issues wrt filtering and weighting and then an attempt at quantifying errors (maybe doomed to failure that one) could make this a very important contribution in a field where all the research lacks sufficient independent verfication or challenge.

252. Paul
Posted Nov 17, 2007 at 5:30 AM | Permalink

Sorry,

Third line should of couse read

Craig has not mirrored…

carry on.

253. JS
Posted Nov 17, 2007 at 5:30 AM | Permalink

#247

Yes indeed – although my comments apply to any non-linear filters one might contemplate as well. In any case, with linear filters, I would suggest, that it’s easy to dispense with the smoothing of individual data series for precisely the reason you state. Smoothing of the final series might be done for presentational purposes – but why otherwise would you do it? It also means you can plot the data all the way to 1995.

254. Will J. Richardson
Posted Nov 17, 2007 at 5:34 AM | Permalink

(Trying one more time)

Dear Dr. Emile-Gaey,

Since you are presently working with Dr. Mann on a paper, could you please ask him to provide some assistance in resolving the issues presented on this Climate Audit thread? Code would be nice.

Regards,

WJR

255. Posted Nov 17, 2007 at 5:46 AM | Permalink

re 235:
Craig sent me 15 files yesterday, I am looking into the details.

256. Douglas Foss
Posted Nov 17, 2007 at 7:29 AM | Permalink

Geoff #237

Two points continually recur: (1) climate currently warmer than last [supply interval], and (2) rate of change in climate temperature is greater than ever. Your comment is directed at x-axis considerations; that is that fewer data points measured on the x-axis means that the investigator may miss events occurring within intervals recorded on the x-axis. As you point out, one might miss a spiked fever and therefore not be aware of both the highest temperature and the fastest rise in temperature.

In RC comments, Gavin takes the position that considerable information exists for the current interval (forget the source for now) and that one can derive the relative rate of warming in the current interval. I thought that the entire point of paleoclimate research was to obtain information concerning past fluctuations to draw comparison with current fluctuation. Generally speaking, such analysis would afford information concerning ranges of temperature, particularly in the Holocene and other interglacials and relative rates of change. The first would allow some analysis of, among other considerations, whether the current warming is atypical and capacity of organisms and ecologic niches to adapt to changes. The second would allow, at a minimum (and in addition to the issues mentioned for the first) analysis of whether drivers other than CO2 have more or less dramatic impact on temperature and information from which to understand better how these drivers actually function (as opposed to how in theory they should operate).

What I wondered about Craigs analysis (and I dont know anything about the actual processes of smoothing) was whether his 18 sets of data points allowed an intelligible assessment of rates of change within the interval. Tree rings generate lots of x-axis information. For a variety of reasons Craig has less confidence in the accuracy of their y-axis data. So, he eliminated tree rings as proxies. I had thought that diatoms in sediments had considerable x-axis information (though bioturbation might generate doubt that we can find individual years in the sediments). And Craig was specific that other series were scant in x-axis data points (every hundred years potentially in some). But, even with smoothing and other operations performed upon the raw data, points on the graph where there are strong slopes should be reacting to y-axis and x-axis information (unless I completely misunderstand these procedures for teasing signal from data). This was the point of the question  given the way Craig proceeded, and the data he had, are the sharp slopes appearing between 800 A.D. and 900A.D. and between 1700 A.D. and about 1750 A.D. informative? It would seem that they would be on the reasoning that they must have reference to the underlying data and should not be merely an artefact of the statistical procedures employed, but I lack the sophistication to determine this.

257. steven mosher
Posted Nov 17, 2007 at 8:01 AM | Permalink

Nasif, sorry about the misspellings. I’ll just watch.

258. Craig Loehle
Posted Nov 17, 2007 at 8:25 AM | Permalink

the greenland data is ice core not borehole. typo. Why did I smooth before averaging? The data series have different degrees of resolution. Some are annual, but others have only points decades apart. If I did not smooth, the annual series would dominate the response. Because of the data gaps it is not possible to answer the question of Foss about rapid rates of change.

In constructing the GISS or CRU data, sites are averaged at each date. There is not much different about what I am doing than that, except that the underlying temperatures at each date are estimates from proxies instead of from a thermometer.

259. Steve McIntyre
Posted Nov 17, 2007 at 8:30 AM | Permalink

#255. Craig, can you send me the data as well so that I can post it up or better, can you post it up yourself with your SI?

260. Posted Nov 17, 2007 at 8:34 AM | Permalink

Craig, nice paper. I have four suggestions (partially repeating some others above).

1. A table that lists, for each site, the following: lat, long, elevation, proxy, freq, refs, notes, data-url (if feasible).

2. An equal-area map of the world (e.g.), showing the locations of the sites.

3. Some consideration of the Slutsky effect.

4. An explanation of why you cannot provide confidence/likelihood intervals.

Regarding #4, it is obviously better to acknowledge that you do not know how to calculate a well-founded answer than to present an ill-founded answer. (I recognize that in the hurly-burly world of scientific publishing, that is sometimes forgotten, but that does not change the veracity.)

Regarding the bootstrap, what your paper does seems like a reasonable approach to me. It is not a correct bootstrap, though. If you are interested in bootstrap, a very good review is by Young G.A. et al. [Statistical Science, 9: 382–415 (1994)].

Proper bootstrapping requires modeling the structural interrelationships in the data. Our current understanding of the structure is poor, however; so I suspect that we cannot adequately do the modeling. In other words, I am skeptical that bootstrap can be reliably done with paleoclimate data.

I had some discussion about using bootstrap in dendroclimatology last year, on the denrdo email list:
http://listserv.arizona.edu/cgi-bin/wa?A2=ind0605&L=itrdbfor&T=0&P=2593
This was regarding the Precon dendroclimatological program, which relies on bootstrapping for its confidence intervals. In that discussion, the authors of Precon (dendrochronologist Hal Fritts and statistician Joel Guiot) came to agree with my comments.

261. Craig Loehle
Posted Nov 17, 2007 at 8:35 AM | Permalink

I will need to post links to the data since the data are not mine to post. This can’t happen before monday because the webmaster does not work 24/7 like this site. I will try to put the links here later this weekend.

262. bender
Posted Nov 17, 2007 at 8:35 AM | Permalink

snip

263. bender
Posted Nov 17, 2007 at 9:02 AM | Permalink

Look at how the planet-saving alarmists obstruct progress on important scientific questions. I ask nicely in #222 if the team can re-run the Li et al. analysis without bcps, and I get a cheeky reply in #230 imploring me to do it myself. Maybe the team *IS* addicted to bcps, as Steve M has hypothesized.

Tell, you what, JEG, [snip] you send me the script and data and I’ll do the re-analysis tonight. Or maybe you can pass my request on to Dr. Li if you are simply not up to the task.

Or … is it just that monopolizing authorship and controlling the scientific process is more important to you than getting an answer to the question? Or … maybe you already know the answer what happens when you pull the faulty proxies out? [If you have run the analysis already and locked it away in a censored directory somehwere, that would be … interesting … and not without precedent.]

Let’s get to it, friend.

264. Steve McIntyre
Posted Nov 17, 2007 at 9:45 AM | Permalink

Here are perhaps relevant urls:

265. Jean S
Posted Nov 17, 2007 at 10:04 AM | Permalink

bender, unfortunately, French is not among the languages I somewhat understand 😉

266. rhodeymark
Posted Nov 17, 2007 at 10:06 AM | Permalink

Re #232 – Thanks John, that was illuminating. Just as Mr. Gore has held workshops to raise up a different sort of proxy to go forth and evangelize, here we see what purports to be a critical examination of the HS presented by an associate of Dr. Mann. It’s cute how young JEG and Cobb are, I hope they haven’t been coddled in their ascent. I found it surprising when it was revealed how fresh Mann’s doctorate was when he was placed in such a position of prominence, but I suppose that in such a rapidly evolving field it shouldn’t be surprising to have new experts baked fresh daily.
I look forward to the continuation and if need be, evolution of Dr. Loehle’s work. I’m grateful that he saw fit to roll up his sleeves in an area where there was an acknowledged need, and trust that it will spur on more beneficial work. One thing I really enjoyed about this thread was Douglas Foss in #57 offering historical insights along the timeline. CA The Movie will absolutely need historians rebutting the current consensus concerning the “global” prosperity of warm vs cold periods. It would seem the coolings inspire a much nastier sort of diaspora, historically. I certainly don’t want the Canadians showing up at my door with knives in their teeth 🙂

267. Posted Nov 17, 2007 at 10:28 AM | Permalink

# 249

What explanation is there for the steep reversals in temperature?

If Dr. Judith Lean et al. based their reconstructions on deuterium and beryllium isotopes and the sunspots series, the explanation is simple. I ask you to see the collage I made with Dr. Craig’s graphs and Dr. Lean’s data which included the time series of ANNUAL mean irradiance, which I had to plot again because her graph conveniently disappeared from the Web. Please revise the collage here: # 241

You can see that the graphs of Dr. Craig match correctly with the variation of the intensity of solar irradiance from 1611 to 2000. IMHO, this is a review in support of the methodology of Dr. Craig. Contrast Mann’s Hockey Stick with Lean’s graph on SI and the correlation of HS with ISI reduces to almost zero.

268. Posted Nov 17, 2007 at 10:35 AM | Permalink

# 111

UC,

Introduce a polynomial trend for each plot (Craig’s and Mann’s) and the similitudes will vanish before your astounding eyes. 🙂

269. steven mosher
Posted Nov 17, 2007 at 10:39 AM | Permalink

snip

270. Bob Meyer
Posted Nov 17, 2007 at 11:21 AM | Permalink

Re 253:

JS said “It also means you can plot the data all the way to 1995.”

True, but I suspect that the averaging was done first because the x-axis points were not the same for all 18 data sets. Using a moving average filter first can serve as a kind of interpolation to make it possible to average the data sets later.

Unless I completely misunderstood the section on method, this is what Loehle did. In his paper he states

Data in each series had different degrees of temporal coverage. For example, the
pollen-based reconstruction of Viau et al. (2006) has data at 100-year intervals. Other
sites had data at irregular intervals. This data was taken as is without interpolation.
Data in each series were smoothed with a 30-year running mean. This should help
remove noise due to dating and temperature estimation error. If data occurred every
100 years, each point would be stretched by the smoothing to cover 30 years.

I don’t have any experience with comparing relatively sparse, non uniformly spaced data sets so I don’t know what the pitfalls are, if any. I do know that if you use higher order interpolation, (like quadratic or spline) it is very easy to introduce weird spurious high frequency components.

271. Posted Nov 17, 2007 at 11:23 AM | Permalink

JEG in #143 said:

Are you with science, or are you for the obscurantists?

The obscurantists are the ones obscuring, withholding, hiding or otherwise performing 3-card monte tricks with the data as if its too precious for skeptics and commoners.

Recommend to your friends that they put all the data on the table. I’m not a scientist –I’m just a fan in the bleachers who likes good baseball–but it seems to me things could be cleared up pretty quickly if they honored requests for crucial data.

You apparently have much to offer this site and I hope you continue to contribute. But allow me to suggest you forgo the adolescent flaming. Adult scientists shouldn’t be speaking to eachother that way.

Billions, if not trillions, of dollars are about to be spent based on recommendations and prognostications from climatologists like you. That is money that that could be spent on other human and natural crises like drought, famine, disease, poverty, disaster and so forth. You are a young man. I know you don’t want to spend the latter portion of your life with egg on your face. Get the science right. And stop flaming those who are trying to do the same thing from a different perspective.

272. Kenneth Fritsch
Posted Nov 17, 2007 at 11:35 AM | Permalink

With the paper under discussed here being organized and constructed such that the reader can readily follow what Craig has done, does make it a target for criticism and criticism that can be rather quickly formulated and without a deep understanding of statistical methods.

While it may show what some posters here want to see, I would not personally want to suspend my skepticism of the lack of effort in determining the uncertainty in the results  anymore than I would do this for those reconstructions arguing for AGW. I do like Craigs bootstrap and jackknife methods of sensitivity testing that seems to go further than those methods used by Mann in his and his progenitors reconstructions. Beyond this processing one must have yet some testing to do on the appropriateness of using any or all of the reconstructions. It is those individual series used in the reconstruction that should then become the focus of the discussions.

If the purpose of the paper was to show that a series of temperature reconstructions could be averaged together with the singular a prior for selection (of not being tree rings based) I would say that Craig has presented a counterpoint for those series that have been put together to show a trend more readily attributable to AGW. Rather obviously he has not gone beyond that purpose to do any detailed statistical analysis (beyond what in general other temperature re-constructers have effectively done given that after the fact rationalizations are not judged acceptable and stating a confidence limit does make it a valid one) to show that his reconstruction is more correct than lets us say the HS.

It should be an easy exercise for others here, or Craig, to use the data and manipulate it in manners as they see fit for more detailed analyses; something that has been much more difficult when dealing with other reconstructions discussed here. A good start as some have suggested already is to average the data on yearly basis before doing any filtering.

The criticism of not determining how well the series gives a measure of global coverage and thus global average temperatures is valid and can be made of other reconstructions –given that an edict that they are global in character or regionally representative must have some evidence to back it up. I am almost to the point of doing a study of extracting sets of 18 randomly selected stations from the 1221 USCHN stations and determining how much the averages will vary over various time periods from a year to decades of years.

Once again I am disappointed that a number of those who come to visit this blog spend too much time on describing, in not always polite terms, what they see as a generalized POV here and too little enlightening us with their counterpoints.

273. Craig Loehle
Posted Nov 17, 2007 at 11:52 AM | Permalink

Got almost all. Will fill in when I get the last 2.
1) GRIP borehole temperature (Dahl-Jensen et al., 1998);
See Moberg Nature site supplementary material
2) Conroy Lake pollen (Gajewski, 1988);
See Moberg Nature site supplementary material
3) Chesapeake Bay Mg/Ca (Cronin et al., 2003);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2003/
4) Sargasso Sea 18O (Keigwin, 1996);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/keigwin1996/
5) Caribbean Sea 18O (Nyberg et al., 2002);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/nyberg2002/
6) Lake Tsuolbmajavri diatoms (Korhola et al., 2000);
See Moberg Nature site supplementary material
7) Shihua Cave layer thickness (Tan et al., 2003);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/china/shihua_tan2003.txt use col 7 temp
8.) China composite (Yang et al., 2002) which does use tree ring width for two out of the eight series that are averaged to get the composite, or 1.4% of the total data input to the mean computed below;
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yang2002/china_temp.txt
9) speleothem data from a South African cave (Holmgren et al., 1999);
from authoremail sent for archive link
10) SST variations (warm season) off West Africa (deMenocal et al., 2000);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/demenocal2000/
11) SST from the southeast Atlantic (Farmer et al., 2005);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/farmer2005/
12) SST reconstruction in the Norwegian Sea (Calvo et al., 2002);
13) SST from two cores in the western tropical Pacific (Stott et al., 2004);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/stott2004/
14) mean temperature for North America based on pollen profiles (Viau et al.,2006);
http://www.lpc.uottawa.ca/data/reconstructions/index.html
15) a phenology-based reconstruction from China (Ge et al., 2003);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/historical/china/china_winter_temp.txt
16) annual mean SST for northern Pacific site SSDP-102 (Latitude 34.9530, Longitude 128.8810) from Kim et al. (2004);
http://doi.pangaea.de/10.1594/PANGAEA.438838
17) Spannagel Cave (Central Alps) stalagmite oxygen isotope data (Mangini et al., 2005).
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/europe/austria/spannagel2005.txt

274. Craig Loehle
Posted Nov 17, 2007 at 12:04 PM | Permalink

re: Bob Meyer #170 you are correct

275. Susann
Posted Nov 17, 2007 at 12:07 PM | Permalink

As a graduate student in public policy, I follow all the climate blogs with avid interest. I read Mr. McIntyre’s blog because he is an adept watchdog of sorts who nips at the heels of the established climate science community. While that may be annoying, those of us who have studied the history of science know how important skepticism is. My undergraduate and graduate degrees are in science (ecology) and politics, so you an imagine how much the debates over AGW are right up my alley. I try to keep somewhat of an objective stance with respect to the issue, and do not consider myself either an acolyte in the COAGW (Church of AGW) or a “denialist” in the pocket of big oil. I wouldn’t even call myself a skeptic. I am more an interested observer, whose focus is the way the science of climate change has become politicized and what that means for policy makers trying to sort through the science and come up with options. I’m willing to beat up both sides. 🙂 Of course, I’m also a human being and am concerned that whatever it is, the truth must come out so we can either mitigate the effects of global warming (if possible) or avoid costly climate mitigation boondoggles if there is no problem. I tend to think there is a problem but am not settled on the details of the cause or the extent of the problem, and most certainly, what to do from a policy standpoint. So that’s a bit of an introduction to who I am and why I’m here.

As a policy analyst, my main goals are to sort through the science and to sort through the politics in order to come up with options.

1. How does this article stack up against other articles in the same area? Is it good science?

2. What are the flaws/limitations in the article?

3. What is new, innovative?

4. How does it add to the literature?

5. As a policy analyst interest in the current debate and how it affects policy development, paleoclimate is important with respect to the causes of past climate change and the issue of climate sensitivity. What caused previous changes in global climate? How sensitive is the global climate to forcers? What kind of change can we expect from current forcers, natural and anthropogenic? Paleoclimate reconstructions showing past warming (e.g. MWP) and cooling are of interest to me as a policy analyst only in so much as they show what caused the change and how much of an effect changes in climate forcers have. If the global climate is relatively insensitive, anthropogenic forcers may not have as large an effect on climate, and if more sensitive, a greater effect.

What, if anything, does it this article on paleoclimate say about causes of climate change and climate sensitivity?

I am not a climate scientist and so rely on their insights and critiques in order to judge where this fits in the scientific evidence on climate change. I look forward to seeing this article get a thorough review.

276. Costard
Posted Nov 17, 2007 at 12:18 PM | Permalink

Kudos Craig for doing this.

I echo the suggestions about showing the global distribution of the sites. You might show (or list) the proxy locations, and introduce a fourth graph, weighted by hemisphere, or hemi-hemisphere, or whatever seems most rational to the firing squad. I suppose would be a model and would require some space given to discussion of confidence/verification/etc., but then it’s really beginning to seem that you’ll need to address this topic anyway. Maybe bender has some ideas for arriving at comprehensive error bars. They may not be “necessary,” but if they’re at all possible, they would be wise.

P.S. Welcome to pandora’s box.

277. aurbo
Posted Nov 17, 2007 at 12:19 PM | Permalink

JEG,

FYI.

The term denialist has developed a strongly pejorative connotation to a significant segment of the population. The word was only recently coined and meant to apply to those who didnt believe in the holocaust and that the holocaust never actually occurred. (As recently as 2003 it had not been defined in the Merriam-Webster Collegiate Dictionary). To some, its use carries the same invective impact that the N-word would for many people of color. I will assume that your offhand use of the term was borne of ignorance and not deliberate insensitivity.

In the case of climate science, the use of the term denialist would have no etymological validity when compared with the words origin in that the holocaust is a matter of historical record, while AGW is as yet unproven.

Notwithstanding the above, I welcome your participation in and contributions to the CA blog as the ultimate goal of most of us here is to get elicit, as Justice Brandeis stated; Truth, even unto its innermost parts.

278. Larry
Posted Nov 17, 2007 at 12:20 PM | Permalink

Susann, 279:

1. How does this article stack up against other articles in the same area? Is it good science?

2. What are the flaws/limitations in the article?

3. What is new, innovative?

4. How does it add to the literature?

5. As a policy analyst…

You ask some excellent questions. I hope they get answers. Here’s what you’re up against:

274, Kenneth Fritsch:

With the paper under discussed here being organized and constructed such that the reader can readily follow what Craig has done, does make it a target for criticism and criticism that can be rather quickly formulated and without a deep understanding of statistical methods.

In other words, the scientist who doesn’t want the GP to be looking and questioning will write in the most opaque manner possible. Furthermore, the reviewers will also use codespeak for the same reason. I hope what happens here on this blog isn’t that, but this is a work in progress. We don’t know how this is going to turn out. Stay tuned. I hope you’re pleasantly surprised.

279. Steve Huntwork
Posted Nov 17, 2007 at 12:21 PM | Permalink

Craig Loehle;

You have been taking your time in replying with accurate answers and supplying the information that has been requested.

So far, you have been demonstrating your quest for being an honest scientist, no matter where the data may lead.

280. richardT
Posted Nov 17, 2007 at 12:22 PM | Permalink

#275
Craig
Caribbean Sea 18O (Nyberg et al., 2002) is not calibrated as temperature. This core also has a foram-based sst reconstuction. Did you use this? If so which season?

281. UK John
Posted Nov 17, 2007 at 12:29 PM | Permalink

Why bother!. I have learnt from this site not to take any notice of proxies, so called observations, statistics, or any other scientific garbage.

I also learnt, and had it proved, that any on-line or telephone vote or in fact anything involving a computer can be adjusted or falsfied to say whatever you want it to say. I have been involved in putting together corporate accounts so I knew this anyway !

Any body who will not share his full method and data, and subject the data collection to independent scrutiny, is likely a fake, so far that appears to apply to nearly all the Science community.

I much prefer Human History and Archeology, at least all the people involved are DEAD! and its a bit hard to falsify things when you are DEAD.

282. Posted Nov 17, 2007 at 12:30 PM | Permalink

Off-topic but in response to Steven Mosher #121: Steven, more importantly, despite any warming, richer-but-warmer worlds may well be better off than poorer-but-cooler ones even if one agrees with the Stern Review’s estimates that warming would/might reduce GDP by 5-20% “now and forever” — especially for developing countries who are deemed to be most-at-risk of climate change because they lack the fiscal and human resources to cope with any climate change.
See: Is a Richer-but-warmer World Better than Poorer-but-cooler Worlds? forthcoming in Energy & Environment, vol. 18, nos. 7 and 8 (2007). Abstract follows:

Greater economic growth could lead to greater greenhouse gas emissions, while simultaneously enhancing various aspects of human well-being and the capacity to adapt to climate change. This begs the question as to whether and, if so, for how long would a richer-but-warmer world be better for well-being than poorer-but-cooler worlds. To shed light on this issue, this paper draws upon results of the Fast Track assessment (FTA) reported in a special issue of Global Environmental Change: Part A 14(1): 1-99 (2004), which employed the IPCCs emissions scenarios to project future climate change and its global impacts on various determinants of human and environmental well-being. Results suggest that notwithstanding climate change, through much of this century, human wellbeing is likely to be highest in the richest-but-warmest (A1FI) world and lower in poorer-but-cooler worlds. With respect to environmental well-being, matters may be best under the A1FI world for some critical environmental indicators through 2085-2100, but not necessarily for others. An alternative analysis using the Stern Reviews worst-case results for potential welfare losses due to climate change indicates that welfare, adjusted for market and non-market impacts of climate change and the risk of catastrophe, should be highest under the A1FI scenario, at least through 2100.

283. Craig Loehle
Posted Nov 17, 2007 at 12:33 PM | Permalink

Re Nyberg: it was converted to temperature somewhere before I got it from Moberg. New link list:
1) GRIP borehole temperature (Dahl-Jensen et al., 1998);
See Moberg Nature site supplementary material
2) Conroy Lake pollen (Gajewski, 1988);
3) Chesapeake Bay Mg/Ca (Cronin et al., 2003);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2003/
4) Sargasso Sea 18O (Keigwin, 1996);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/keigwin1996/
5) Caribbean Sea 18O (Nyberg et al., 2002);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/nyberg2002/
converted to temperature on the Moberg article nature site suppl material
6) Lake Tsuolbmajavri diatoms (Korhola et al., 2000);
See Moberg Nature site supplementary material
7) Shihua Cave layer thickness (Tan et al., 2003);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/china/shihua_tan2003.txt use col 7 temp
8.) China composite (Yang et al., 2002) which does use tree ring width for two out of the eight series that are averaged to get the composite, or 1.4% of the total data input to the mean computed below;
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/yang2002/china_temp.txt
9) speleothem data from a South African cave (Holmgren et al., 1999);
from authoremail sent for archive link
10) SST variations (warm season) off West Africa (deMenocal et al., 2000);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/demenocal2000/
11) SST from the southeast Atlantic (Farmer et al., 2005);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/farmer2005/
12) SST reconstruction in the Norwegian Sea (Calvo et al., 2002);
13) SST from two cores in the western tropical Pacific (Stott et al., 2004);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/stott2004/
14) mean temperature for North America based on pollen profiles (Viau et al.,2006);
http://www.lpc.uottawa.ca/data/reconstructions/index.html
15) a phenology-based reconstruction from China (Ge et al., 2003);
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/historical/china/china_winter_temp.txt
16) annual mean SST for northern Pacific site SSDP-102 (Latitude 34.9530, Longitude 128.8810) from Kim et al. (2004);
http://doi.pangaea.de/10.1594/PANGAEA.438838
17) Spannagel Cave (Central Alps) stalagmite oxygen isotope data (Mangini et al., 2005).
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/europe/austria/spannagel2005.txt

284. Craig Loehle
Posted Nov 17, 2007 at 12:35 PM | Permalink

There are several requests for a map of the locations. The coordinates of all sites are either at the links or in the publications. Can someone map this please? I don’t have the software. Note that one site represents North America and one China, so not all are points.

285. Posted Nov 17, 2007 at 12:37 PM | Permalink

Larry, #282:

In other words, the scientist who doesnt want the GP to be looking and questioning will write in the most opaque manner possible. Furthermore, the reviewers will also use codespeak for the same reason.

This is an accurate description of obscurantism, a word used rather promiscuously by JEG at the end of #143.

286. Posted Nov 17, 2007 at 12:41 PM | Permalink

Re #286: Link to paper: http://members.cox.net/goklany/Richer-but-warmer%20RV.pdf

287. Craig Loehle
Posted Nov 17, 2007 at 12:43 PM | Permalink

By the way, my goal in this project was simply to see what the history looked like without treering problems. It opens the door to more detailed work.

288. david abrams
Posted Nov 17, 2007 at 12:46 PM | Permalink

“As a relative layperson, Id like to point out how refreshing it is to see a proxy study with clear inclusion criteria (2000 year, 20 points) and exclusion criteria (tree rings).”

I totally agree with this. I’m not a climatologist but I’m an attorney and people lie to me all day long. You could say that I have PhD in BSology. It’s troubling the way that some of the research in these areas seems very open to the possibility of cherry picking and other kinds of data manipulation.

Posted Nov 17, 2007 at 12:50 PM | Permalink

Craig@292

And my goal as a reader is similar. Thank you.

290. rhodeymark
Posted Nov 17, 2007 at 12:51 PM | Permalink

Susann – I would think that #5 is the crux of the biscuit. The way I distilled this paper is that if a reconstruction that shows great paleoclimatic variation can withstand scrutiny, then there is a) definitely one forcing agent that can’t be blamed, and b) other forces that are currently being given an entirely too short shrift.

291. Steve Huntwork
Posted Nov 17, 2007 at 12:53 PM | Permalink

“By the way, my goal in this project was simply to see what the history looked like without treering problems. It opens the door to more detailed work.”

Keep an open mind and allow the data to lead you in ways that you could never expect. It will!

So far, you have impressed me with your honest attempt to analyse the data available to you.

292. Costard
Posted Nov 17, 2007 at 12:55 PM | Permalink

sod:

ending the series in 1995 of course is rather a CONVENIENT thing.

it removes about 7 of the 10 hottest years EVER from the record.

if i did a 2000 year of computer technology analysis, using your methodology and ending around 1960, i might end up with the conclusion that some medieval computing machine was the high point of achievement!

the misrepresentation at the end is already quite bad, by using 1995 as last year. it gets worse by averaging it to 1980. but if a significant number of your proxies have their last temperature data BEFORE 1995 (and i doubt that Conroy Lake pollen (Gajewski, 1988) includes 1995 data..), the smoothing gets even worse.

First of all, Craig has made a compilation of proxies – not modern measurement data. Please reference any proxy which has shown “7 of the 10 hottest years ever” since 1995. Presumably, this would have a 2000-year span, ending in, say, 2006.

Furthermore, since most proxies, especially non-treerings, don’t (accurately) show individual years, they’re probably not going to show anomalies like 1998. As you point out, even the length of the MWP is highly ambiguous. So the proxies may not even show a short peak like 1980-present. Smoothing is a reality of the data.

Since what you seem to be saying is that global warming requires the measured warming of the last two-and-a-half decades for much of its impact, as well as the high frequency of modern data – i.e. the “hottest years” – doesn’t that seem to imply that modern data can be misleading when we’re talking about long-term, millenial temperature reconstructions? Or, similarly, when we’re talking about a climate system that largely follows even-longer-term trends? It seems clear to me that the closer one is able to look, the more the noise will dominate, and so differentiating between noise and a “rapid, unprecedented” rise in temperatures will be difficult.

Perhaps non-centered smoothing, and so extending the graph to 1995, wouldn’t be a bad idea. Others would know better than me.

293. Craig Loehle
Posted Nov 17, 2007 at 12:56 PM | Permalink

In the past year, more data have become available. I am recruiting coauthors to do an improved version of this analysis with more data, going back farther, with maps and error bars and comparisons to other data. As many as want to play are welcome, if they play nice. Just email me.

294. richardT
Posted Nov 17, 2007 at 1:00 PM | Permalink

#292
Craig
“After an extensive search, all data were used that had at least 20 dates over the 2000-year period”
If you scroll slightly past the data for Conroy Lake on your link, there is a data for another lake, Hell’s Kitchen, that fits your inclusion criteria.
While the reconstruction for Conroy Lake is much warmer in the MWP than present, Hell’s Kitchen’s is not. Cherry picking?

295. DocMartyn
Posted Nov 17, 2007 at 1:01 PM | Permalink

“bender says:
November 16th, 2007 at 4:25 pm

Doc Martyn,
You are too funny. Please check this post. Have a great weekend.”

I am sorry bender, that post was before my time (I think). Natural selection is a real problem in using biotic proxies.

Another point is that I had a look at the Be signal vs. this papers wave form. The effect is rather close.
Can anyone get the numbers to this data and plot it the authors figures?

Millennium-Scale Sunspot Number Reconstruction: Evidence for an Unusually Active Sun since the 1940s

Ilya G. Usoskin, Sami K. Solanki, and Manfred Schussler. PHYSICAL REVI EW LETTERS. VOLUME 91, NUMBER 21, 211101, 1-4

http://cc.oulu.fi/~usoskin/personal/Sola2-PRL_published.pdf

296. Susann
Posted Nov 17, 2007 at 1:04 PM | Permalink

Steve, I agree that I don’t care where the data leads, as long as it leads to the facts. I wouldn’t agree that climate reasearch is junk although there is and always will be junk amidst the gems. It’s inevitable, but it can be minimized. We humans are political animals, our training in the scientific method notwithstanding. Scientists are expected to take into account errors and bias in their research design and questions but very often, they are completely unaware of their personal political biases and how those affect every step of the research process from choice of topic to forumlating scientific problems to evaluating findings. And, as in every walk of life, some are outright frauds.

Of course, that said, the scientific method is really all we have, isn’t it? I certainly don’t want to chuck it over. I am all for rigorous oversight and review with as little political interference as possible. We can’t expect issues as potentially politically explosive as climate change and global warming to escape politicization, and so being aware of it and trying to counter it is all the more important when it comes to developing policy. Policy development is hobbled by bad science — like computers, it’s GIGO.

297. Bruce
Posted Nov 17, 2007 at 1:08 PM | Permalink

“The dinoflagellate cyst signals identified from the different Scandinavian coastal waters are attributed to both changes in climate during the past 3500 years and sewage discharge during the past 150 years (summarised in Figure 2). This work establishes G. catenatum cysts as a warmer water signal in the more open southern Scandinavian waters, and suggests a biogeographic boundary for high amounts (> 2 %) south of Bergen. The maximum concentrations of G. catenatum correspond with the warmest climate during the Medieval Warm Period (1000 – 1200s), and the onset of persistent low amounts of the species corresponds with the coldest climate during the Little Ice Age “climax” (1600s).”

http://folk.uio.no/thort/personlig/thesis.htm

298. Steve Huntwork
Posted Nov 17, 2007 at 1:11 PM | Permalink

Once upon a time, in a land far away:

In 10th grade High School, my science teacher had us do an experiment. He threw a weight attached to a long stream of paper off the school roof, and an electrical buzzer would make marks upon the paper as it moved. Our requirement as students was to measure the change in the buzzer marks on the paper and deduce that gravity caused the weight to fall at 9.8 meter per second squared.

I got an F for that experiment, because the fall of the weight was NOT 9.8 meters per second and I refused to give the expected answer.

However, my science teacher absolutly loved me for calculating the coefficent of drag for a weighted strip of paper, as a function of it’s length. We both learned something that day.

Why does anyone AVERAGE data? The real science is in the details and why it does not conform to conventional theory. When I read any report that only presents averaged or smoothed data, I throw it in the trash can.

I want the details, and want to know WHY this data set is not conforming to the conventional theories.

That is what honest science is all about!

299. Susann
Posted Nov 17, 2007 at 1:16 PM | Permalink

rhodeymark

The way I distilled this paper is that if a reconstruction that shows great paleoclimatic variation can withstand scrutiny, then there is a) definitely one forcing agent that cant be blamed, and b) other forces that are currently being given an entirely too short shrift.

I think that past variation is an accepted fact in paleoclimatology from what I’ve read of it. The question is what caused that variation? How much of a variation took place? What does that degree of variation say about climate sensitivity? What are the implications for today?

We’re still debating what proxies to use and how to use them. The other questions, the ones that most interest me (cause, degree of sensitivity, implications) won’t be addressed until we settle those debates.

300. Posted Nov 17, 2007 at 1:19 PM | Permalink

# 300

DocMartyn,

I have the series for ISI based on 10Be and Ca from NOAA. They published them here. Plot it along the delta TT series and you’ll get a nice surprise.

301. John Norris
Posted Nov 17, 2007 at 1:23 PM | Permalink

re 196: JEG

Yes, i did note that, and i find it very entertaining that when Caspar Amman is struggling with publication deadlines, it deserves a Wheres Caspar ? entire thread, but that when Steve McIntyre is busy, .

Put in perspective:
– Probable time delay for McIntyre comments: a few days
– Ongoing time delay for Casper Amman publication: 3 years or so, and a year after accepted in AR4 as a published paper

I dont think you are going to make any headway with this audience, with this sort of comparison. It might work elsewhere though.

Since Steve stated he would comment later, I am sure that if he doesn’t review and provide comment on this paper, he will agree to give you a thread here in three years to castigate him for it.

his army stands still to hear what he has to say because they cant form a judgment by themselves.

There is plenty of judgment demonstrated amongst over 300 comments here, most of it not equivocating days to years.

302. JS
Posted Nov 17, 2007 at 1:26 PM | Permalink

Re #258 and #270

Craig, I think you need to be clear about two things then – interpolation and smoothing. These fulfil different functions and combining things can muddy the waters. As Bob noted, with linear filters the order of application doesn’t matter. You need to interpolate data to annual frequency before you average it – but that is only necessary for some series and to different extents. Indeed, how are you applying a 30-year centred moving average to data with less than annual frequency? While you state that the data were not interpolated, you also state “If data occurred every 100 years, each point would be stretched by the smoothing to cover 30 years.” This comment seems to skip a few steps and isn’t entirely clear to me. How have you gone from one point every century to something that you can a apply a 30-period moving average to? You must be doing some interpolation prior to that step. More exposition of how you applied a 30-year smooth to decadal or centennial data would be beneficial. The key here will be the interpolation, not the 30y MA.

I’m not sure why you are concerned that “If I did not smooth, the annual series would dominate the response.” – any high frequency idiosyncratic noise will be attenuated by the averaging. And, as Bob noted, it will be attenuated to exactly the same extent if you only smooth (linearly) after computing the average. What process do you imagine you would apply to average the series if you didn’t smooth (but obviously interpolated)?

303. Steve Huntwork
Posted Nov 17, 2007 at 1:29 PM | Permalink

“Steve, I agree that I dont care where the data leads, as long as it leads to the facts. I wouldnt agree that climate reasearch is junk although there is and always will be junk amidst the gems.”

Without access to the raw data, it is impossible to analyze the details that do not conform to current scientific theory. And without those details, new science becomes impossible.

Anyone that uses AVERAGES, is trying to force their raw data to conform to something that they expect to see.

On AVERAGE, my example of a weighted paper tape falling off of a building would give the required answer of 9.8 meters per second squared. But it would be WRONG!

Knowledge is learned, by studying those things that do not fit what you expected.

304. Gary
Posted Nov 17, 2007 at 1:32 PM | Permalink

1. How does this article stack up against other articles in the same area? Is it good science?

It’s a ‘methods’ paper addressing criticisms of paleo-temperatures reconstructions from proxies using tree-rings. It doesn’t use new data; however, unlike many recent reconstructions, it sets out selection criteria a priori to minimize ‘cherry-picking’ bias. That makes it ‘better’ science. It’s clearly written, concise, and doesn’t speculate beyond the data.

2. What are the flaws/limitations in the article?

Lacks metadata on the proxies, especially a map or table of the locations. There may be other statistical methods that could be used (but this is beyond my competency to comment on).

3. What is new, innovative?

Not particularly new in a general sense, except that this sort of analysis seems to be regarded as unnecessary in dendroclimatology unlike in many other disciplines where methods are scrutinized more severely.

4. How does it add to the literature?

It’s additional evidence against using treerings as temperature proxies. This sort of thing should have been done long ago to evaluate the validity of treering data. It adds to the literature because it comes so late in the game and questions some assumptions that have a higher likelihood of being wrong than once thought.

305. bender
Posted Nov 17, 2007 at 1:32 PM | Permalink

Susann #289 & #292,
A good start to answer your question would be to re-do the work of Li et al. (2007) minus the bristlecone/foxtail/junk that Steve M has sniffed out for us. But you see what JEG’s reply to my proposal is?: a smiley wink. Steve M is too classy to say it, so I will. This tells you something: they fully know that without the active ingredient that they’re addicted to, the pesky MWP comes back.

306. Posted Nov 17, 2007 at 1:39 PM | Permalink

# 308

Steve Huntwork,

Yeah! That’s the reason I don’t trust GCMs. Oh, dear! GCMs are so vulnerable… Heh! 😉

Oops! A thunderstorm here in November? Wow! That’s a deep “climate change”…!

307. richardT
Posted Nov 17, 2007 at 1:44 PM | Permalink

#309

Its additional evidence against using treerings as temperature proxies

Look at the comparison between Loehle’s and DArrigo’s curve shown by Rob in #59. Despite the former having practically no dendroclimatological data, and the latter being entirely dendroclimatological, they are remarkably similar.

308. bender
Posted Nov 17, 2007 at 1:45 PM | Permalink

Dr. Loehle,
Do you have a volunteer yet to do the mapping of the proxy co-ordinates? I’ll do it if no one else wants to. Let me know ASAP.

309. Steve Huntwork
Posted Nov 17, 2007 at 1:46 PM | Permalink

Why is raw data so important, why how averages can distort?

Normalize each day’s high temperatures to the exact same value and plot the minimum temperatures as a negative delta. No AVERAGING is allowed.

Is there a trend?

Is there an obvious seasonal trend, and if so, remove that seasonal trend and see what is left. Is there a known solar influence that can be removed? Remove it and see what is left.

The study of what is left, is where the real science will be located!

310. Steve Huntwork
Posted Nov 17, 2007 at 1:56 PM | Permalink

Any GCM model that does now show a warming of the global Earth’s temperature between January and March, is false.

Who can tell us why?

311. Steve Huntwork
Posted Nov 17, 2007 at 2:34 PM | Permalink

A solstice occurs twice a year, whenever Earth’s axis tilts the most toward or away from the Sun, causing the Sun to be farthest north or south at noon. The name is derived from Latin sol (sun) and sistere (to stand still), because at the solstice, the Sun stands still in declination, that is, its movement north or south is minimal. The term solstice can also be used in a wider sense as the date (day) that such a passage happens. The solstices, together with the equinoxes, are related to the seasons. In some languages they are considered to start or separate the seasons; in others they are considered to be center points (in English, in the Northern hemisphere, for example, the period around the June solstice is known as midsummer, and Midsummer’s Day is 24 June, about three days after the solstice itself).

Here is an outstanding video that shows the change in the size of the Sun, as viewed from Earth:

http://epod.usra.edu/archive/epodviewer.php3?oid=196160

Any GCM that does not reflect such an obvious change in Solar inflence upon the Earth between July and January, must be false.

NEVER AVERAGE!

312. Steve Huntwork
Posted Nov 17, 2007 at 2:43 PM | Permalink

Is the Earth warmer in January or July?

Is the Earth closer to the Sun in January or July?

If the proxy or instrumental data does not show such an obvious fact, why not?

There is only one possible way that “global temperatures” could be warmer in July. Why is something so obvious being ignored?

313. richardT
Posted Nov 17, 2007 at 2:43 PM | Permalink

A map of the proxies. NB 2 from China, 1 from N. America

library(maps)
map()

pos=list(grip=c(73, -38),con=c(46, -68),che=c(38, -76),sar=c(33, -57), car=c(18, -67), tsu=c(68, 22), shi=c(40,116),sa=c(-24, 29.2),wa=c(20.75, -18.58),sea=c(-25.5, 13),vor=c(66.967,7.633),wtp1=c(6.3, 125.83),wtp2=c(-5, 133.44),np=c(34.9530, 128.8810), sp=c(47.0882, 11.6715))

sapply(pos,function(p)points(p[2],p[1], col=2, pch=16))

314. Steve Huntwork
Posted Nov 17, 2007 at 3:05 PM | Permalink

For 30 years, I have always asked some rather simple questions:

1) Acid rain: Why where the trees dying at the top of the hills, instead of in the vallies where human produced pollusion would be concentrated? Today, we know that they were dying of old age.

2) Ozone hole: Why does nobody realize that ozone is created from solar radiation, and for six months out of the year, the polar regions do not get any sunlight. In the spring, when solar radiation begins to illuminate the polar regions, you get a VERY HIGH concentration of ozone around the poles? I call this the ozone donut, but everyone focused upon the hole in the middle of the donut and ignored what was right around it. Today, we now understand that the Sun creates ozone.

3) Global warming: Why does nobody ask why the historical records show a maximum global temperature in July instead of January? That is not possible, because of the Earth’s orbit.

Oh well, the obvious is always rather difficult for some people to understand….

315. bender
Posted Nov 17, 2007 at 3:11 PM | Permalink

#321 Did you place Viau et al (2006) proxy #14 at Ottawa? It should be all of North America. Any other approximations of this type?

316. bender
Posted Nov 17, 2007 at 3:13 PM | Permalink

Gaping holes in the network in South America, Russia, India, Antarctica. Still, nicely dispersed.

317. rhodeymark
Posted Nov 17, 2007 at 3:18 PM | Permalink

I think that past variation is an accepted fact in paleoclimatology from what Ive read of it.

Oh, to be sure, but that fact is not just minimized but some would say manipulated or distorted (see “Dr. Thompson’s Thermometer”). Once the “in” scientists get the policy makers to play Stepford Wife, they then pass it down to the rubes through the media as “unprecedented” etc. Is it really? That’s what I want to know.

318. richardT
Posted Nov 17, 2007 at 3:20 PM | Permalink

#327
That site is Conroy Pond. I shaded N. America and China to represent the three regional reconstructions.

319. DaveR
Posted Nov 17, 2007 at 3:21 PM | Permalink

#73 Craig: E&E review was as rigorous as for any other journal Ive submitted to (of my 107 pubs).

Theres a real lesson here. Some CA regulars are quick to defend E&E, but the fact that E&E accepted Craigs paper when JEG so quickly showed it to be fundamentally flawed is damning for the journal (sorry Craig, but thats the way it is).

320. bender
Posted Nov 17, 2007 at 3:26 PM | Permalink

Re #331 Fundamentally flawed? Prove it.

321. Posted Nov 17, 2007 at 3:29 PM | Permalink

re 321:
Thanks for The R-Script RichardT! Here is the map from your script:

322. Steve Huntwork
Posted Nov 17, 2007 at 3:29 PM | Permalink

http://epod.usra.edu/archive/epodviewer.php3?oid=196160

Did you actually view that? Do your own astronomy search on the subject of Earths orbit around the Sun.

Ok, now I will shut up….

323. bender
Posted Nov 17, 2007 at 3:31 PM | Permalink

My fault, RichardT. Your second quote in “grey70” (in your #321 script) gets font-shifted to a ‘?’ when I copy and paste.

324. Steve Huntwork
Posted Nov 17, 2007 at 3:32 PM | Permalink

@333

Not a bad “global” sampling of data….

325. Gerald Machnee
Posted Nov 17, 2007 at 3:34 PM | Permalink

Re #331 – When JEG does a proper critique of several of the Hockey Team’s papers including their archiving, I will begin to take him seriously. What we have seen is something like a car manufacturer in the early 1900’s – You can have any proxy (color) you want as long as it is BCP (black).

326. bender
Posted Nov 17, 2007 at 3:36 PM | Permalink

Hans Erren #333. Not quite. Check your quotes. China, US, Canada, should all be gray. Please fix & repost? Thanks.

327. Posted Nov 17, 2007 at 3:36 PM | Permalink

re 335:
same for me, Icouldn’t fill countries in the first run, I had to substitute the funny wordpress quotes with plain ones, then it worked. Try using ‘code’ tags when posting code.

328. Craig Loehle
Posted Nov 17, 2007 at 3:38 PM | Permalink

Bender, yes please do plot the data I have no volunteer yet.

Smoothing question. For data with equal intervals (all annual, for example) it does not matter if you smooth and then average or converse. But when one data point in one series is only every 100 years, an annual data series will completely dominate the signal. Try it. There is not perfect way to deal with this type of data. Interpolate? Linear filter? Gaussian filter? Each has pitfalls and will create distortions of the underlying data. Create some data where different series are sampled at different intervals and try diff methods– will get diff results.

329. richardT
Posted Nov 17, 2007 at 3:40 PM | Permalink

Map with labels – beware of the quotes. Trying code tag
library(maps) map() map(regions=c("Canada","USA","China"),col="grey70",fill=T, add=T)

 pos=list(GRIP=c(73, -38),Conroy=c(46, -68),Chesapeake=c(38, -76),Sargasso=c(33, -57), Caribbean=c(18, -67), Tsuolbmajavri=c(68, 22), Shihua=c(40,116),Cold_Air_Cave=c(-24, 29.2),ODP_658C=c(20.75, -18.58),ODP_1084B=c(-25.5, 13),MD952011=c(66.967,7.633),MD98_2181=c(6.3, 125.83),MD98_2176=c(-5, 133.44),SSDP_102=c(34.9530, 128.8810), Spannagel=c(47.0882, 11.6715)) 

pos2

330. steven mosher
Posted Nov 17, 2007 at 3:41 PM | Permalink

RE 331.

Hmm.

“#73 Craig: E&E review was as rigorous as for any other journal Ive submitted to (of my 107 pubs).
Theres a real lesson here. Some CA regulars are quick to defend E&E,
but the fact that E&E accepted Craigs paper when JEG so quickly showed it to be fundamentally flawed is
damning for the journal”

I think that would be damning for ALL journals. If you accept Craig at his word,

Further, JEG didnt show it to be fundamentality flawed. JEGHEAD reraised issues raised by
everyone else, notably bender, a full day later. He added the twist of being snide.

By your logic then if bender or JEGHEAD or Anyone can criticize a paper in a day, then the journal is bankrupt?
Seems fair. I like that logic. Let’s see who survives:
HEY BENDER take a wack at Nature and Michael Mann.. or Willis take a wack at Juckes and climate of the Past.

331. Larry
Posted Nov 17, 2007 at 3:41 PM | Permalink

338, they are on my machine (with firefox). Maybe it doesn’t render correctly with certain machines?

332. richardT
Posted Nov 17, 2007 at 3:44 PM | Permalink

retry
library(maps) map() map(regions=c("Canada","USA","China"),col="grey70",fill=T, add=T) pos=list(GRIP=c(73, -38),Conroy=c(46, -68),Chesapeake=c(38, -76),Sargasso=c(33, -57), Caribbean=c(18, -67), Tsuolbmajavri=c(68, 22), Shihua=c(40,116),Cold_Air_Cave=c(-24, 29.2),ODP_658C=c(20.75, -18.58),ODP_1084B=c(-25.5, 13),MD952011=c(66.967,7.633),MD98_2181=c(6.3, 125.83),MD98_2176=c(-5, 133.44),SSDP_102=c(34.9530, 128.8810), Spannagel=c(47.0882, 11.6715)) pos2=t(sapply(pos,function(p)p)) points(pos2[,2],pos2[,1], col=2, pch=16) text(pos2[,2],pos2[,1], col=2, label=rownames(pos2), pos=c(2,2,2,2,2,4,2,4,2,2,2,2,2,2,2), cex=.7) 

333. Craig Loehle
Posted Nov 17, 2007 at 3:57 PM | Permalink

Thanks for the map. I still don’t see “fundamentally flawed” All I hear is needs better confidence intervals (which I did using 2 methods, just not the ultimate perfect method). JEG comments about models and RE and R2 don’t even make sense. Sorry.

334. DaveR
Posted Nov 17, 2007 at 4:09 PM | Permalink

#332, 345 etc. re: “fundamentally flawed”, JEG put it neatly, if rather unkindly, thus in post #194:

…isnt it staggeringly misleading to call this a global temperature reconstruction ? (did i misread, or is it the title of the article ?). The adjective Global implies representativeness of an area-weighted average, which it is not. Now, it may turn out that your spatial sampling does a reasonably job at representing tropics, mid and high-latitudes , but it seems a little careless not to ensure it, and even more unforgivable no neglect mentioning it.

Craig – it would be very interesting to see the reviewers comments from E&E. Did any of them pick up on this?

335. Posted Nov 17, 2007 at 4:11 PM | Permalink

Craig,

I think there are already maps on the reconstruction of MWP published. It will be positive if we take a look to this article. I know that the stand of Sally Baliunas has been the focus of denialists of nature, but look for the work, not for the human being.

336. Posted Nov 17, 2007 at 4:12 PM | Permalink

First of all, Craig has made a compilation of proxies – not modern measurement data. Please reference any proxy which has shown 7 of the 10 hottest years ever since 1995. Presumably, this would have a 2000-year span, ending in, say, 2006.

NASA-GISS.

http://tamino.wordpress.com/2007/11/10/temperature-2007/#more-476

Furthermore, since most proxies, especially non-treerings, dont (accurately) show individual years, theyre probably not going to show anomalies like 1998. As you point out, even the length of the MWP is highly ambiguous. So the proxies may not even show a short peak like 1980-present.

this is obvious: using several different papers, all of which have some “MWP” peak somewhere between 800 and 1200 will create some sort of a plateau there.
his approach is HELPING the MWP thesis, which so far fails to give a period that is exact up to a century even!

on the other hand, his methodology REMOVES the last 25 years, basically enforcing that the current spike will not show up.

do you think it makes sense that he calls it a “2000 years temperature reconstruction” and leaves out the last 20?

those years that are so important, that they fill countless blog pages?

Smoothing is a reality of the data.

i am not 100% sure of this, but others here know much more about statistics than i do.

Since what you seem to be saying is that global warming requires the measured warming of the last two-and-a-half decades for much of its impact, as well as the high frequency of modern data – i.e. the hottest years – doesnt that seem to imply that modern data can be misleading when were talking about long-term, millenial temperature reconstructions? Or, similarly, when were talking about a climate system that largely follows even-longer-term trends? It seems clear to me that the closer one is able to look, the more the noise will dominate, and so differentiating between noise and a rapid, unprecedented rise in temperatures will be difficult.

Craig decided to make a comparison between the MWP and present, not me.

One persistent question is whether the MWP was really warmer than the end of the 20th century.

it is hard to assume, that this paper was meant as anything but ammunition against the hockey stick. it should at least try to include the hockey stick period.

Perhaps non-centered smoothing, and so extending the graph to 1995, wouldnt be a bad idea. Others would know better than me.

good first step, yes.

If data occurred every 100 years, each point would be stretched by the smoothing to cover 30 years. This comment seems to skip a few steps and isnt entirely clear to me. How have you gone from one point every century to something that you can a apply a 30-period moving average to? You must be doing some interpolation prior to that step. More exposition of how you applied a 30-year smooth to decadal or centennial data would be beneficial.

well said. another important information missing. why did you chose 30 year period anyway?

Its a methods paper addressing criticisms of paleo-temperatures reconstructions from proxies using tree-rings. It doesnt use new data; however, unlike many recent reconstructions, it sets out selection criteria a priori to minimize cherry-picking bias. That makes it better science. Its clearly written, concise, and doesnt speculate beyond the data.
..
Its additional evidence against using treerings as temperature proxies. This sort of thing should have been done long ago to evaluate the validity of treering data. It adds to the literature because it comes so late in the game and questions some assumptions that have a higher likelihood of being wrong than once thought.

sorry, but this is pure fiction!
1. we have nothing but the word of the author on the non-bias criterias.
(end date 1980 sounds like a LOT of bias to me..)

2. if it was “better science” it would not be published in E&E

3. it speculates a LOT beyond its data, mainly about a period that it has none on.

4. you prefer to speculate beyond the paper as well? or is the assumption you are speaking about not the hockey stick?

337. Craig Loehle
Posted Nov 17, 2007 at 4:13 PM | Permalink

by the way I want to thank Steve M for the posts about Arabian Sea data which has issues-so I didn’t use that.

338. Steve Huntwork
Posted Nov 17, 2007 at 4:13 PM | Permalink

Craig:

Like it or not, the JEG comments have helped you create a better data analysis. I for one, have been very impressed with how rapidly you have attempted to answer those questions.

That is what honest science is all about.

339. Larry
Posted Nov 17, 2007 at 4:14 PM | Permalink

346, as opposed to the Mannomatic Treemometer™ in California that telleconnects to the entire world?

It’s fine to say that that qualification should be spelled out more explicitly, but I don’t think it’s honest to call that “fundamentally flawed”. Not unless jeg wants to say in the same breath that MBH is, too.

340. bender
Posted Nov 17, 2007 at 4:18 PM | Permalink

Whether the paper is “fundamentally flawed” or not (and it’s not) is irrelevant because the author has ‘moved on’. Seriously. One by one the criticisms are being addressed (mapping, documentation, turnkey scripting, etc.). Eventually all of them will be addressed and then we will see whether CWP is “unprecedented”.

As for statistically robust confidence intervals – the one real sticky wicket – let’s just use MBH99 method. Oh, yeah, I forgot. We don’t actually know what that method was. They’re unaccountable for their methods.

Now, Li et al. (2007) claim to have a methodological solution, but guess what: JEG says they’re not interested in trying it on the Loehle (2007) proxies. That’s one hell of a solution.

JEG, you can’t have it both ways. You can’t own a monopoly on the methods and expect your work to run the public policy agenda. It’s undemocratic. Take your choice: monopoly on methods OR sharing data to help drive policy.

341. Posted Nov 17, 2007 at 4:19 PM | Permalink

First of all, Craig has made a compilation of proxies – not modern measurement data. Please reference any proxy which has shown 7 of the 10 hottest years ever since 1995. Presumably, this would have a 2000-year span, ending in, say, 2006.

sorry, misread that one. i don t have the data of the Buentgen paper, but i d start with that one:

http://www.wsl.ch/staff/jan.esper/publications/Buentgen_2005_CD.pdf

the problem is NOT his choice of papers. i understand that data is limited. Craig just needs to change the title and stop speculating about the hockey stick and the “end of the 20th century”.

a disclaimer in the abstract would be nice as well, so that people are not misguided into thinking this gives any new information about what is happening NOW.

342. steven mosher
Posted Nov 17, 2007 at 4:23 PM | Permalink

333.

since thermometers are teleconnected at a range of 1200KM ( hansen) It would be kinda
neat to see 1200km rings around the sites..

343. Stan Palmer
Posted Nov 17, 2007 at 4:24 PM | Permalink

re 353

a disclaimer in the abstract would be nice as well, so that people are not misguided into thinking this gives any new information about what is happening NOW.

A real question:

Why would someone use proxies to measure current temperature?

344. bender
Posted Nov 17, 2007 at 4:27 PM | Permalink

Re #354
Sure, why not … with the correlation field.

345. tetris
Posted Nov 17, 2007 at 4:29 PM | Permalink

Re:346
DaveR/JEG
But unarchived data conjured from one geographically unique stand of bristlecones through Mannmagic however do provide proof of 1] no MWP and 2] unprecedented temp increases since 1980 as in the Hokey Shtick?

346. kim
Posted Nov 17, 2007 at 4:29 PM | Permalink

Did you know you have a thread almost 1300 comments long at Pharyngula named after you, Stan?
=============================================================

347. Larry
Posted Nov 17, 2007 at 4:31 PM | Permalink

Why would someone use proxies to measure current temperature?

Because they’re accurate to within 0.1C (per Mann)?

348. Kenneth Fritsch
Posted Nov 17, 2007 at 4:33 PM | Permalink

Re: #282

You ask some excellent questions. I hope they get answers. Heres what youre up against:

274, Kenneth Fritsch (said):

With the paper under discussed here being organized and constructed such that the reader can readily follow what Craig has done, does make it a target for criticism and criticism that can be rather quickly formulated and without a deep understanding of statistical methods.

(and you, Larry, responded)

In other words, the scientist who doesnt want the GP to be looking and questioning will write in the most opaque manner possible. Furthermore, the reviewers will also use codespeak for the same reason. I hope what happens here on this blog isnt that, but this is a work in progress. We dont know how this is going to turn out. Stay tuned. I hope youre pleasantly surprised.

I am not certain how you have interpreted what I said, but what I meant to say was that Craig has written an article sufficiently clear in descriptions of what he has done that there will be no delay for many interested parties in the GP to comment on it and critique it. In fact he has made it possible to rather easily repeat what he has done and do it with other approaches. I am in effect applauding what Craig has done here and contrasting it to what was done with Mann and other Mannian like reconstructions.

At the same time I am reserving any judgements on the validity of the series that went into the reconstruction, its global coverage and the appropriateness of the methods used for averaging until more analyses are completed and questions asked. As you and Craig have stated, the article is a work in progress and the approach he has taken will allow active participation and analyses at this blog. If we can avoid the inclination to get personal, Craig has initiated something that can be really fun and a great learning experience at the same time.

349. Larry
Posted Nov 17, 2007 at 4:33 PM | Permalink

358, and they’re not very nice comments, either.

350. Craig Loehle
Posted Nov 17, 2007 at 4:34 PM | Permalink

Sod: the proxies available do not go past 1995. If you want to account for that, add a few tenths at the end. I wasn’t playing with the data. Where did I get 30 years? It is a convention in climate studies, but people use other periods also. If there wasn’t bias by reviewers, I wouldn’t have to publish in E&E. You seem to misunderstand the question of bias. Mann’s method picked out proxies (tree rings) that had a hockey stick shape and weighted them very very heavily in the averaging of series. THAT is bias. Other people seem to pick tree series or ice core data that they like and ignore others. THAT is bias.

351. Bernie
Posted Nov 17, 2007 at 4:40 PM | Permalink

sod:
The HS is a broken metaphor with well-defined MWP and LIA visible in proxies. I don’t understand your point.

352. Larry
Posted Nov 17, 2007 at 4:42 PM | Permalink

360, actually, what I was really trying to get across with the “work in progress” comment is that the process of a pre-review by blog is a new concept, and while I have high hopes, we really won’t know how this works out until it’s tried a few times. What I’m hoping is that it’s not only going to be effective in working a lot of the bugs out prior to submittal, but it’ll also subject the paper to a lot of eyes that would otherwise not see them; i.e. statisticians.

A side benefit is the general public gets to watch the process from the bleachers, and can even interact (though that’s the part that could get out of hand).

353. bender
Posted Nov 17, 2007 at 4:42 PM | Permalink

Hey Craig,
If you want the series to extend to 2000, just repeat the last value five times. As JEG well knows, this kind of manipulation wouldn’t be unprecedented. 😉

354. Posted Nov 17, 2007 at 4:43 PM | Permalink

# 350

Steve Huntwork,

I agree. Craig has answered each questioning and uncertainty with that professionalism that it’s hard to find “somewhere else”. Craig Loehle has not hidden his data and methodology. I would like that others “somewhere else” followed the example of real science given by Dr. Loehle and the aperture demonstrated by Dr. Steve McIntyre to all kind of arguments. Steve McIntyre gives us the opportunity to explain our arguments and to debate the arguments from others.

I know that he is odious to make comparisons, but as I passed through the experience of being banned and I couldnt defend my work, I think that I have the right to make the comparison. One of my papers was strongly criticized in Real Climate. I did try to support my paper scientifically, but they did not allow me to express a word to make the pertinent explanations on the paper. They even made fun from quantum mechanics, and I could not refute their odious mockery because they did not allow me to do it.

Thus, open your eyes, Julien. You demanded and pushed Craig to reveal even the minimum detail of his investigation, and soon you ended here to express badly from all those that displeased you; nevertheless, Steve McIntyre allowed you to speak and write your drolleries. Can you see the difference?

355. kim
Posted Nov 17, 2007 at 4:44 PM | Permalink

No data about what is happening NOW; only the inference that this warming is not unprecedented.
==========================

356. Larry
Posted Nov 17, 2007 at 4:46 PM | Permalink

363, which raises a question in my mind: if the MWP and LIA are visible in the reconstructions, and the current warming isn’t, could we be underestimating the magnitudes of the MWP and LIA? It seems like either that has to be true, or the current surface data are exaggerated.

357. Craig Loehle
Posted Nov 17, 2007 at 4:51 PM | Permalink

The only inferences that can be drawn are 1) tree rings and other proxies give different results and 2) it is plausible that the MWP existed, but we need more data. I hope these claims aren’t too hysterical and loud.
Now I’m going out for the evening, so don’t think I am ignoring you. I’ll be back first thing Chicago time in the morning.

358. Craig Loehle
Posted Nov 17, 2007 at 5:03 PM | Permalink

According to my 2005 paper, the magnitude of the MWP may be underestimated due to dating error.

359. Pat Keating
Posted Nov 17, 2007 at 5:08 PM | Permalink

365 bender

Oooh, that’s cold!

360. rhodeymark
Posted Nov 17, 2007 at 5:21 PM | Permalink

Dr Loehle – RichardT asked about Conroy Lake vice Hell’s Kitchen in #299. Since it seemed relevant to the above, was there an answer that I missed?

361. Bob Meyer
Posted Nov 17, 2007 at 5:24 PM | Permalink

#346 quoting #194

Global implies representativeness of an area-weighted average

Global implies nothing of the sort. Any randomly distributed choice of sites across the continents can claim “globalness”. The issue of globalness is whether the choice of sites in inherently biased in a way that would cause the data to be skewed, not whether the data fits some particular distribution scheme. If you suspect bias in the choice of sites then identify it and suggest a way to eliminate it. That would be very helpful.

The basic assumption here, as I understand it, is that there is a “great global climate driver” whose effects are manifested everywhere to some degree. Therefore any group of sites whose differing characteristics are purely random should show the effect more clearly when taken as an aggregate. What Loehle is doing is trying to ferret out that driver’s signal and then contrast it with the signals from the tree rings. Would more sites better distributed produce more accurate results? Yes. Does more accurate imply that Loehle’s results are inaccurate? No.

There seems to be the feeling here that since Loehle’s paper has not addressed every conceivable objection that it has addressed no question at all. Loehle’s claims are simple and modest: 1) there are differences between tree ring proxies and other proxies and 3) the non tree ring proxies strongly suggest that the LIA and MWP were real.

362. rhodeymark
Posted Nov 17, 2007 at 5:25 PM | Permalink

Darn, bad timing. I hope you have some well deserved relaxation.

363. Philip_B
Posted Nov 17, 2007 at 5:30 PM | Permalink

365 Larry, it seems all roads in climate science lead back to the divergence problem. A problem Craig should leave well alone in his paper.

http://www.climateaudit.org/?p=1530

364. Henry
Posted Nov 17, 2007 at 5:33 PM | Permalink

In terms of “warmest ever” the final paragraph

One persistent question is whether the MWP was really warmer than the end of the 20th century. Even keeping in mind that Figure 1 shows 30-year running means, it would indeed seem to show the MWP to be warmer than the late 20th century. The eighteen series used here show a mean difference of about 0.3°C between the MWP and the 20th century (range of 0 to 0.6°C difference over the periods). It must be emphasized, of course, that this result is based on limited data.

seems to use some weasel words; there is a difference between the 20th century as a whole and the late 20th century.

365. bender
Posted Nov 17, 2007 at 5:47 PM | Permalink

Re #373 JEG’s complaint is not about “globalness” but “temperatureness” of the recon. As not all proxies are equally correlated to temperature, JEG wants Dr L to weight each of the proxies according to its correlation with temperature during the instrumental period. That will change the shape of the mean curve to some degree. Whether it changes a lot or a little, no one knows until it is tried. There is nothing unreasonable about this request. Not doing it doesn’t mean the paper is flawed, however.

JEG is upset at the wording of the title, which indicates that Loehle puports to be reconstructing temperature. Strictly speaking, he is not. So the title is a little misleading. But this is not the fatal flaw that JEG makes it out to be. It means you might want to change the title a little.

What JEG fails to appreciate is that it is the autocorrelation structure of the recon that is the issue here, i.e. that the mean and variance are largely irrelevant (to the purpose at hand). If you wanted to estimate temperature from the proxy data you would have to get the mean and variance right, through calibration. But if all you’re interested in are relative temperature anomalies, then you don’t need to do this. Since the real question here is whether MWP was warmer than CWP, there is no need to turn the calibration crank. Calibration is technically challenging, but it is scientifically unnecessary to test the hypothesis.

Technicians are fond of turning cranks, and of “raising the bar” for publication by forcing other people to do so. That’s how they keep their edge on the competition. Team X can do ‘A’ therefore Team Y should have do it also. Never mind that ‘A’ is irrelevant to the hypothesis. It’s just publication gamesmanship. [JEG] will learn this as he matures. Good Editors can spot it in an instant, and consider it in that context.

366. Steve Huntwork
Posted Nov 17, 2007 at 5:49 PM | Permalink

#366 Nasif Nahle:

“One of my papers was strongly criticized in Real Climate. I did try to support my paper scientifically, but they did not allow me to express a word to make the pertinent explanations on the paper.”

My profesional expierence of writing scientific publications, was for the Atmopheric Sciences Labratory of the U.S Army. My specialty was in Lidar measurements of obscurants. Global warming was able to fund some of the research that I did, but not once did my data support this concept.

Oh, I was smart enough to word my formal data reports with the proper language to make the people who were paying for the project happy, but the raw data was rather neutral.

During the first Gulf War, I used the DMSP satellite data to predict what was happening in Iraq. For some strange reason Saddam was not willing to share accurate weather data with the rest of the world, so I had to rely upon our satellites.

Ok, the DMSP satellite data was fantastic in a time of war, but would I ever use it as an absolute calibration for everything else? Heck no!

The MSI sensor on the DMSP satellites measures the illumination of multiple CO2 bands. If you know the pressure and temperature (using radiosond measurements from a balloon), then you can convert the MSI CO2 data into a temperature or pressure profile.

During the first Gulf War with Iraq, this is all we had to work with, and the MSI data was absolutly invaluable.

But to use the MSI or SSI satellite data as a “standard” for today’s climate analysis, does make me want to cry.

Sometimes, people need to step back and take a deep breath. What exactly are you actually measuring?

REALITY CHECK!

367. steven mosher
Posted Nov 17, 2007 at 6:14 PM | Permalink

Re 380. have a look at JEG’s paper on ENSO. I mean on GCMs simulating ENSO

http://rainbow.ldeo.columbia.edu/~alexeyk/Papers/Emile-Geay_etal2007inpress.pdf

368. Posted Nov 17, 2007 at 6:25 PM | Permalink

I think the PC title of the paper should have been:

An almost 2000-year global temperature reconstruction based on mostly non-treering proxies.

😀

369. BarryW
Posted Nov 17, 2007 at 6:29 PM | Permalink

Re 379

If you wanted to estimate temperature from the proxy data you would have to get the mean and variance right, through calibration.But if all youre interested in are relative temperature anomalies, then you dont need to do this.

Doesn’t this assume a linear relationship between the temp and the proxy even if your just using anomalies?

370. Bob Meyer
Posted Nov 17, 2007 at 6:35 PM | Permalink

Nasif # 366 said

One of my papers was strongly criticized in Real Climate. I did try to support my paper scientifically, but they did not allow me to express a word to make the pertinent explanations on the paper.

Sometimes I think that the “Real” in “Real Climate” is used in the Old English sense of “royal”. RC sure does act as though they were royalty dealing with serfs. Theirs is to expound, ours is to acquiesce and obey.

It’s gotten too hard for me to wade through their stuff. I let others do that and then I follow their lead if they find something that sounds interesting. I wish that their site was completely without value, then I wouldn’t have to go there at all.

371. Jaye
Posted Nov 17, 2007 at 6:37 PM | Permalink

Nasif re:387,

Sorry, I was referring to JEG’s usage of the term.

372. kim
Posted Nov 17, 2007 at 6:39 PM | Permalink

‘paucity’, perhaps?
===========

373. JS
Posted Nov 17, 2007 at 6:41 PM | Permalink

#297 and non-centred smoothing.

It won’t help. The only difference between a 30-year centred moving average and a 30-year non-centred moving average would be the dating of the points – the last point will be exactly the same only in one scheme it will be labelled 1980 and the other it will be labelled 1995. (Assuming just an equal weighting of all points – some sort of tapering would affect this.) Non-centred moving averages induce phase shifts in the data because they lag the actual data. Centred moving averages effectively adjust for this.

Basically, all smoothing methods have end-point problems. Either you end the smooth early or your smoothed data will be subject to revision as new data becomes available.

374. Jaye
Posted Nov 17, 2007 at 6:41 PM | Permalink

Regarding the JEG and others of the “RC” ilk, I just wish they would be honest with themselves by using the word that they are really thinking…heretic. Just say it guys…it’ll make you feel better.

375. jimdk
Posted Nov 17, 2007 at 6:42 PM | Permalink

Maybe Craig needs to use the word “confounding”. The warmers do

“An especially suitable strategy to minimize confounding effects is to sample sites along ecological gradients, such as elevation or latitude (Fritts and Swetnam 1989, Bugmann 1996). For example, Naurzbaev et al. (2004) selected sites along latitudinal (from 55 to 72°N) and elevational (from 1120 to 2350 meters above sea level) transects and used the parameters of the Regional Curve Standardization to infer climatic influences and past temperature variability. Other strategies are available to improve tree ring reconstructions of surface temperature. Some of these strategies involve using maximum temperature instead of mean temperature (Luckman and Wilson 2005), combining multiple tree ring parameters related to temperature (Helle and Schleser 2004), sampling species with opposing responses to temperature (Biondi et al. 1999), and applying mechanistic models to tree ring records (Anchukaitis et al. 2006).”
by biological and environmental factors other than climate. Site selection and quality control procedures have been developed to account for these confounding factors. In the application of these procedures, emphasis is placed on replication of records both within a site and among sites and on numerical …
At the
bottom of PAGE
11 … is not known exactly. Furthermore, all proxies are influenced by variables other than temperature, and it can be difficult to account for these confounding factors. The use of linear regression in the calibration step is also a concern because reconstructions derived from linear regression models based …”

http://www.nap.edu/catalog.php?record_id=11676

376. bender
Posted Nov 17, 2007 at 6:48 PM | Permalink

Doesnt this assume a linear relationship between the temp and the proxy even if your just using anomalies?

Yes, good point. But that is what the Team typically is willing to assume. That doesn’t mean it’s right. My point is that unless the nonlinearity is severe the autocorrelation structure is not going to change much. With an upside downquadratic tree-ring response, however, you have a problem.

This is precisely why JEG and I both suggested that some significant discussion is required of underlying proxy accuracy.

377. windansea
Posted Nov 17, 2007 at 6:49 PM | Permalink

Loehles claims are simple and modest: 1) there are differences between tree ring proxies and other proxies and 3) the non tree ring proxies strongly suggest that the LIA and MWP were real.

bingo, so many great quotes in this thread, so little time

I’ve been waiting for someone with credentials and balls enough to write such a multi proxy study that shows a global MWP and LIA, and I like the simple averaging with no weighting.Any fool can see these proxies are globally situated and not regional as usually claimed, there are scores of these peer reviewed proxy studies from all 7 continents as well as globally situated ocean proxies listed at http://www.co2science.org/scripts/CO2ScienceB2C/data/mwp/mwpp.jsp which are dismissed with much waving of hands.

“we have to get rid of the MWP” that’s what got me started 🙂

Thank you Dr Loehle! Make it better as comments suggest.

378. JS
Posted Nov 17, 2007 at 6:56 PM | Permalink

#340
“But when one data point in one series is only every 100 years, an annual data series will completely dominate the signal. ”

I’m not sure what you really mean by this. A one in a hundred year observation is unlike an annual series and to treat it like an annual series with 99 missing values is wrong. The most obvious interpretation is that the one in a hundred year observation represents the average of the century. To convert to annual frequency you just put that average in for every year in the century. If the underlying data generation process is different you might do something different.

You seem to be suggesting that you give 1/100th the weight to the centennial series when you average. That is obviously silly. You have to interpolate in some way. The simplest approach based on the approach alluded to above is to use the same data point for all annual observations +/- 50 years from the data point you have (or the 100 years before depending on the way the data are collected). You then have something that looks like a step function that changes every hundred years. As you mention, there are alternatives.

But regardless, you must have done some sort of implicit interpolation to convert one observation every 100 years into an annual series (smoothing or no smoothing). So what interpolation have you used for these series? If you set out the process you used to convert 100-year data to annual data our conversation will be easier and the apparent misunderstanding will likely be resolved.

379. bender
Posted Nov 17, 2007 at 7:12 PM | Permalink

Steve Huntwork, thanks for your comments (and for clarifying what you were originally trying to say). But could you try to get them inserted into the appropriate thread? This thread is going to be a long one, and it ought ot be narrowly focused on Loehle (2007).

380. Posted Nov 17, 2007 at 8:20 PM | Permalink

Susann, like you I come to CA from a public policy perspective. If you hunt around CA you will find more analysis of tree ring series than you could possibly ever need. The take away: treerings are potential proxies for a variety of variables: drought, temperature and actual CO2 levels. But, as proxies they have significant and salient problems.

Given that tree ring proxies lie at the heart of the IPCC analysis and the Gorian alarmism and that these views are driving public policy vis a vis climate change it makes a lot of sense to look at them closely. Craig’s article is an attempt to use another, ringless, set of proxies to see where the climate may have been. As such it is a very valuable baseline in assessing the value of the tree ring mavens’ work and, with that, the plausibility of the IPCC’s proposals. (There is no point in looking at Gore as his work is entirely derivative and is, after all, show biz.)

381. MrPete
Posted Nov 17, 2007 at 8:36 PM | Permalink

382. Susann
Posted Nov 17, 2007 at 8:51 PM | Permalink

Jay, I will poke around a bit more to find the tree ring posts. My inclination would be to conclude that excluding an entire proxy type might be a problem, esp. if in doing so, the results are more “acceptable” for one side — just as including it might lead to more acceptable results for the “other” side. In other words, not including tree ring data results in a MWP while including them eliminates or minimies MWP. Why is the MWP important? (I think I know the answer, but want to work through the logic.) This seems to be one of if not “the” focal point of this paper and much of the debate. Should it be?

Steve, sorry to appear too sensitive.

383. BarryW
Posted Nov 17, 2007 at 8:56 PM | Permalink

Re 389

It would seem that a form of sensitivity analysis would be a way of validating the technique used. Redo the 100 yr data as a step function, linear interpolation or maybe even drop out that series and see how it affects the result. Conversly could you just sample or average the annual data to the 100 yr sample rate and again look at the overall shape of the curve to see if it conforms to what you had before?

384. Posted Nov 17, 2007 at 9:32 PM | Permalink

I must agree with Bender (#16, 87), and Julien Emile-Geay (JEG #143) that Craig Loehle’s paper would have been greatly improved with some standard errors and confidence intervals. We can’t say that his MWP is really warmer than his LIA, eg, until we see some error estimates.
Craig (#73, 178, 214) questions how to do this when his proxies have divergent or even unreported measurement errors themselves. This is a good question, but turns out not to be a big problem.
Suppose we have n observations y_i = mu + e_i, but var(e_i) = v_i, which is different for every observation but unobserved. Craig is estimating mu with the simple average y-bar. Assuming independence, var(y-bar) = (1/n^2)Sum(v_i). As long as the v_i’s are not too wildly distributed, Sum(v_i) is consistently estimated by the Sum of Squared Residuals SSR = Sum(y_i – y-bar)^2. Therefore the traditional formula sqrt(SSR/(n*(n-1)) will consistently estimate the standard deviation of y-bar about mu, and will provide asymptotically N(0,1) t-tests (or “z-tests” if you prefer) for hypotheses.

These t-stats will not, however, exactly have the classical small-sample t-distribution in this heteroskedastic (unequal-variance) case, because SSR will not have the required chi-squared distribution, even if the e_i’s are Gaussian. Nor will the traditional degrees of freedom adjustment (n-1) be precise in small samples, since this also requires homoskedasticity (equal variances), if not Gaussianity. So Craig should go ahead and report the traditional standard errors, with the equalification that they are only asymptotically valid because of the heteroskedasticity introduced by the unequal (and unnown) measurement errors of his sources. His webpage cited in the paper (www.ncasi.org/programs/areas/climate/Loehle#&#2007.csv) would be a better place for this suplementary material than here, however, since the reader of his paper would not know about this website, let alone this thread.

If Craig had good estimates of the errors of his source series, he could quantify the total error variance and then use Weighted Least Squares (WLS) to efficiently estimate mu and compute precise t-stats. Meanwhile, the above is good enough.

Craig (#150, 164, 178) is correct, however, to reject Julien’s demand (#143) for indicators of fit like R^2. R^2 measures how much better one’s regression model fits than a model with just a mean and no regressors. Since, as Craig points out, he (unlike his sources) is not fitting a regression, his R^2 is identically 0 and not worth reporting. The fact that Julien insists (#194) anyway demonstrates either that he does not understand basic statistics, or else that he is just trying to flimflam his audience. Perhaps this works for him over at RC.

[snip]

385. Posted Nov 17, 2007 at 9:50 PM | Permalink

RE #385 — my bad, I meant to type
http://www.ncasi.org/programs/areas/climate/LoehleE&E2007.csv . However, this is just a spreadsheet with his numbers, not a webpage per se. He ought to put a “supplementary materials” webpage on the NCASI site with a link to the paper, the links to his data sources, his point estimates and standard errors, the map of his sites, and a pointer to any future papers he does on this topic. If it’s ultimately linked to the NCASI homepage, Google will eventually pick it up. I’d like to see a spaghetti graph (love that pasta!) of his source series, before and after his smoothing, with a heavier black line of his point estimates. Also a graph of his point estimate with 95% confidence interval.

386. nanny_govt_sucks
Posted Nov 17, 2007 at 10:09 PM | Permalink

To get “Global” coverage for the proxies in this study, I think the way to do it is to simply claim that they are teleconnected to global average temperatures. Actually, then you only need to include one proxy to claim you have a “global” reconstruction. Teleconnections make things a lot easier.

387. Susann
Posted Nov 17, 2007 at 10:17 PM | Permalink

Larry

In other words, the scientist who doesnt want the GP to be looking and questioning will write in the most opaque manner possible. Furthermore, the reviewers will also use codespeak for the same reason. I hope what happens here on this blog isnt that, but this is a work in progress. We dont know how this is going to turn out. Stay tuned. I hope youre pleasantly surprised.

I want to respond to this earlier, but BSG intervened. I’ve worked for scientists (as a lab assistant), have written a few (unpublished) scientific papers (as a student) and have worked as a policy analyst. When you study science, you have to learn a whole new language, terminology, methods, techniques, etc. It really is a rarefied atmosphere, not necessarily because anyone is trying to be opaque (although some might relish sounding opaque) but because of the high degree of specialization involved. Sometimes, there is no simple way of putting a complex issue or concept. What appears as flimflam might just be irreducible complexity. Or not, depending on the case. Knowing which is which — that’s the rub.

Now, when I worked for a government department, I had to de-buzzwordize technical and scientific research for the consumption of politicians and bureaucrats — so they could understand it and make decisions based on it (and their competing interests). The translation from science to standard comprehensible English is dangerous for a lot of the complexity and uncertainty can get lost. There’s a fine balance between readability and validity. Very often, the sense of caution and uncertainty that exists in scientific studies gets lost when the findings are taken into the public domain. What is preliminary and potentially interesting becomes slam-dunk in the political realm. On both sides of this debate, I’ve seen this happen. It’s a minefield.

388. Jim Clarke
Posted Nov 17, 2007 at 10:37 PM | Permalink

Sod,

You seem to be fixated on the last 20 years of the data, ignoring the fact that the main problem with ‘hockey stick’ reconstructions is not the blade, but the stick. No one is denying that global temperatures have generally warmed over the last 100 years. Still, in order to discredit the statement that this work indicates that the MWP was warmer than late 20th century temperatures, you would have to assume that those last 15-20 years would reveal a rise of 0.40 degrees C. Since no temperture measurement of any kind shows such a rapid warm-up over the years in question, your protestations lack substance.

389. Steve McIntyre
Posted Nov 17, 2007 at 11:06 PM | Permalink

Craig – some questions. You refer to an email from Holmgren. How does that differ from data at ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/africa/cold_air_cave.txt?

In a couple of cases, the ur;s have two different temperatures (Nyberg, de Menocal) – which column did you use?

390. Posted Nov 17, 2007 at 11:12 PM | Permalink

Susann, #388:

Very often, the sense of caution and uncertainty that exists in scientific studies gets lost when the findings are taken into the public domain.

Yes. Exactly. That is why this blog exists and has become so popular. Furthermore, many people here believe that the sense of caution and uncertainty in scientific studies that you speak of was lost before the information was submitted to governments and other related bodies like the IPCC that constitute the so-called “public domain.” And that it was further massaged and compromised once the bureacrats got their mits on it.

Self-serving agendas abound.

391. Gunnar
Posted Nov 17, 2007 at 11:25 PM | Permalink

#383 >> Why is the MWP important? (I think I know the answer, but want to work through the logic.) This seems to be one of if not the focal point of this paper and much of the debate. Should it be?

Susann, this is the sort of question that I have asked many times on CA, and this particular question specifically. Although I’m generally trying to avoid commenting here because of a deep frustration with some posters, I recognize a kindred spirit in your question. One reason is that if you are treated in a similar way, at best, your question would be ignored, and at worst, if you persisted, people would hurl ad-hominems to shut you up.

Why? I think it’s because you ask an uncomfortable question. If I understand your point of view from the little information in your question, I would surmise that you believe that the MWP is not so important. If true, then the entire battle plan that many people have spent a lot of effort on is irrelevant. They won’t like to face that prospect.

From a purely scientific logic point of view, the MWP should not be important, since if it’s hotter now than in Medieval times, AGW could still be false. Similarly, if the MWP was hotter than it is now, AGW could still be true. It’s hardly evidence either way. Yet, AGW proponents and anti-AGW skeptics are going to the mattresses over this apparently unimportant issue. Why?

Well, the reason is that the AGW proponents have asserted a very simplistic (and insufficient) logic in favor of their position:

premise: gosh, it’s hot
conclusion: let’s restrict man’s right to use energy

They really have not made any effort to use the scientific method to establish the scientific case, supporting the many scientific prerequisites that would have to be true, in order for AGW to be true.

For various reasons, the anti-AGW forces have chosen only to poke holes in the argument made, rather than trying to explore the scientific question itself. As such, the response from the anti-AGW side is “it’s not that hot”. As a neutral independent auditor, Steve M has successfully pointed out that various papers written by AGW proponents supporting the case that “wow, it’s hot” have significant scientific and mathematical errors.

And because the anti-AGW forces happened to make the inadequate counter point that “it’s been hot before”. The AGW proponents, apparently oblivious to the extreme weakness of that argument, decided to go all out to revise history, erasing the MWP from the record.

So, on the one hand, it would seem an unlikely way to win the war for either side. Regardless of which side prevailed, they would do so without ever actually making a substantial case. On the other hand, in retrospect, this is often the case in big wars. Saratoga was minor, except that it was the turning point of the american war for independence. Victory in the Pacific could be traced back to Midway. Dukakis would be president, except for that minor question asked by Al Gore about weekend furloughs. And perhaps, years from now, they will say, the AGW issue was decided, based on whether or not the MWP existed.

392. Steve McIntyre
Posted Nov 17, 2007 at 11:37 PM | Permalink

If you google Why is the hockey stick important? you can find attempts by both me and McKitrick to answer this.

As an IPCC reviewer for AR4, I said that, if the HS was not relevant to policy issues, then the entire paleoclimate chapter should be deleted from the assessment report. The “consensus” was for its inclusion, so I presume that climate scientists still consider it relevant. Long before the document was drafted, I suggested to an organizer that AR4 include a careful exposition and articulation of the physics underlying the AGW effect and all feedbacks. But they decided not to do that either.

393. bender
Posted Nov 18, 2007 at 12:06 AM | Permalink

Susann,
1. Warning in advance: do not feed the troll.
2. If you ask good questions they will be answered. Just keep them focused on Loehle (2007) for this thread and post more general questions on “unthreaded”. General commentary on science-policy issues doesn’t really fit in this thread (although there is some tangential relevance.)
3. The purpose of ClimateAudit is to audit climate science, to ensure accountability and transparency in the way scientific information is generated and synthesized. Obstructionism, opaqueness and obfuscation are loathed at CA. The site’s purpose is not to act as an authoritative mouthpiece for a consensus view. It is to make sure that assumptions and uncertainties are clear, so that everyone can work from the same set of facts.
4. Because the blog is uncensored there is a fair amount of noise that some find excessive. Just like real life.

394. jaye
Posted Nov 18, 2007 at 12:20 AM | Permalink

392…excellent post.

395. David
Posted Nov 18, 2007 at 1:15 AM | Permalink

#391

That’s right, it only influences the label. What’s all this fuss about averages? Why do it anyway. Maybe for interpolation, but that doesn’t seem to be the point here. It seems to me to be mainly for presentation purposes. For people unaccustomed to noisy data it helps to see the trend, but it isn’t neccessary. In fact, it obscures important features of the data. But the view that the 30 year central average cuts off events more recent than 1980 is obviously wrong. If subsequent temperature proxies indicated a large increase after 1980 that would show up in an increase in the 1980 moving average.

I’m thinking that a much simpler statistical analysis could be done. Test the hypothesis that the current temperatures are the hottest in the last thousand (say) years. The exact timing of the MWP and errors in the X-axis wouldn’t matter then.

396. Posted Nov 18, 2007 at 1:29 AM | Permalink

#383 >> Why is the MWP important?

It’s more political than scientific. The unfamiliar is scary; the more alarmist politicians can paint recent changes as unfamiliar, the easier it is to scare the public. Some on the AGW alarmist side would like to claim not just that it’s been gradually getting warmer since the little ice age, but that it’s getting dangerously warm or warming at a dangerous rate. A few even postulate an imminent “tipping point” such that once the global temperature gets above X degrees, we’re all doooooomed.

But if we know the temperature has been above X within recent human history, that should remove some of our sense of urgency. Maybe we don’t need to be quite so alarmed. Maybe we have time to wait a few more decades, let the science solidify and just see what happens rather than panicking and shutting down the engines of economic progress.

As an attempt to rewrite history, the hockey stick gives the whole AGW-assessment project a bad name. Skeptics reasonably figure that good data and good science shouldn’t need to be embellished, exaggerated, hidden, or protected from opposing analysis. The fact that the hockey team tries so hard to protect their bad science makes it hard to credit even some of the good science being done in their area. We need more papers that positively add to the good science, rather than only negatively tear down the bad science. With any luck, Craig’s paper will move things in that direction.

In any case, at least it’ll make for more interesting “spaghetti” charts! 🙂

397. aurbo
Posted Nov 18, 2007 at 1:44 AM | Permalink

Susann

Whether or not there was a MWP that was warmer than today is irrelevant as to whether we are currently undergoing significant warming and whether such warming will expand to catastrophic levels. What happened 1000 years ago neither affirms nor refutes today’s temperature rise.

The real importance of the MWP is that if it really existed then the relationship between today’s warming and the anthropogenically caused increase in atmospheric CO2 as being the the most prominent, if not singular cause is seriously damaged. This is because there is no indication that elevated levels of CO2 existed back in the MWP days so there must have been another cause for the temperature rise then and that cause could not be anthropogenic.

398. pliny
Posted Nov 18, 2007 at 2:14 AM | Permalink

Re #383
I agree about the irrelevance of the MWP to the validity of AGW. But I disagree about the war analogy. AGW is either happening or it isn’t. If it is, the Earth will go on getting hotter until there is no possible doubt. And if it isn’t, AGW will fade away. It won’t be decided by a battle over the MWP.

399. pliny
Posted Nov 18, 2007 at 2:37 AM | Permalink

#392, the last comment (#400) responds to Gunnar, and only indirectly to #383. Sorry about that.

400. Ivan
Posted Nov 18, 2007 at 2:47 AM | Permalink

SOd says

do you think it makes sense that he calls it a 2000 years temperature reconstruction and leaves out the last 20?

Ask Michaels Mann the same question.

401. Posted Nov 18, 2007 at 3:00 AM | Permalink

Sod,

You seem to be fixated on the last 20 years of the data, ignoring the fact that the main problem with hockey stick reconstructions is not the blade, but the stick. No one is denying that global temperatures have generally warmed over the last 100 years. Still, in order to discredit the statement that this work indicates that the MWP was warmer than late 20th century temperatures, you would have to assume that those last 15-20 years would reveal a rise of 0.40 degrees C. Since no temperture measurement of any kind shows such a rapid warm-up over the years in question, your protestations lack substance.

sorry, but yes i have sort of a “fixation” with what is happening at this moment. sorry.

you mean no temperature measurement apart from measuring the temperature shows that rapid increase?

(just by eyeball: 1980 sligthly below +0.2, and an endpoint slightly below +0.6)

and of course the lack of an error estimate is a massive problem here!

But the view that the 30 year central average cuts off events more recent than 1980 is obviously wrong. If subsequent temperature proxies indicated a large increase after 1980 that would show up in an increase in the 1980 moving average.

from what Craig gives us, we don t even know whether there are any proxies past 1980. without checking his literature, we can t be sure if any data point in the 20th century was used at all.

using his methodology with the right parameters, you could come to the conclusion that a REAL hockey stick doesn t have a blade either..

i would still love to see his method applied to NASA-GISS up to 1995. how will the “hockey stick” look, if we do 30 years averages and end early?

#383 >> Why is the MWP important?

Its more political than scientific. The unfamiliar is scary; the more alarmist politicians can paint recent changes as unfamiliar, the easier it is to scare the public. Some on the AGW alarmist side would like to claim not just that its been gradually getting warmer since the little ice age, but that its getting dangerously warm or warming at a dangerous rate. A few even postulate an imminent tipping point such that once the global temperature gets above X degrees, were all doooooomed.

But if we know the temperature has been above X within recent human history, that should remove some of our sense of urgency. Maybe we dont need to be quite so alarmed. Maybe we have time to wait a few more decades, let the science solidify and just see what happens rather than panicking and shutting down the engines of economic progress.

funny, but i DO think that the MWP is important. my conclusion of course is a completely different one:

we currently have a CO2 driven warming.

we know that in the past, other factors have lead to significant warming.

if we are unlucky, those two might COMBINE at any moment.

think of a river. adding some extra water sources upstream has lead to some significant floods lately. now you discover, that there were even worse floods BEFORE the change. will this comfort you?

Steve:
Please try to stay on the thread. The impact of CO2 could be debated on every thread, but I believe that there’s a value to examining particular papers and particular details in and of themselves and prefer to keep topics on thread,

402. Stan Palmer
Posted Nov 18, 2007 at 3:07 AM | Permalink

re 403

we know that in the past, other factors have lead to significant warming.

Not according to the Mann/IPCC hockey stick

403. Ivan
Posted Nov 18, 2007 at 3:38 AM | Permalink

Steve: snip – please don’t debate off-thread issues on this thread. I know that you’re rising to someone else’s point, but please don’t. I’ve deleted some other digressions.\

404. rhodeymark
Posted Nov 18, 2007 at 7:00 AM | Permalink

from what Craig gives us, we don t even know whether there are any proxies past 1980. without checking his literature, we can t be sure if any data point in the 20th century was used at all. using his methodology with the right parameters, you could come to the conclusion that a REAL hockey stick doesn t have a blade either..

Still banging that kettle at 3 am? Craig has stated openly above that the data ended in 1995. The rest is bad faith, and considering that he has welcomed co-authors to refine the work product, you may as well smash that badly skipping record already.

405. rhodeymark
Posted Nov 18, 2007 at 7:03 AM | Permalink

Sorry Steve – I see you are awake 😉

406. MrPete
Posted Nov 18, 2007 at 7:11 AM | Permalink

Susann:
The MWP question does have scientific significance, from what I’ve seen.
The AGW concept describes, by definition, an unprecedented process.
Suppose that today’s warming is unprecedented. If so, that in itself is not proof of AGW but provides significant room for AGW hypotheses.
However, suppose that today’s warming, whether in value or rate of increase, is nothing special in the last few thousand years. If so, that would falsify most AGW hypotheses.
Thus, the size and “shape” of the MWP is quite significant for the AGW question.
Yes, it appears true that nobody has proven that A has caused today’s GW, nor has anyone analyzed historical climate well enough to prove what drove the MWP and LIA. The fact that we don’t really understand our climate all that well appears not to matter to most real climate scientists, nor to policymakers. Find a big-picture “match” and they’re confident enough to recommend drastic “fixes” with unknown actual impact.
And that’s why Craig’s paper is important.

Sod: there are several problems with the river scenario:
* We must remember that the reservoir was quite low 400 years ago (LIA)
* Major disagreement on where the recent water is coming from (CO2, solar, etc etc)
* Major disagreement on whether we can control the water sources (can we reduce solar? does planting
trees help or hurt? etc)
* Major disagreement about what is the reasonable/helpful range of levels in the reservoir
(was MWP good? LIA bad? Is the status quo really “best”?)
* Many ignore that the reservoir is so large it has its own mechanisms beyond river inlets/outlets (clouds
apparently are a negative feedback, not positive — by analogy, reservoir evaporates, forming clouds that
carry moisture away… I know, it’s a ridiculous comparison ;)… think of the analogy here, not the mechanism)
* Major disagreement over whether the reservoir is about to overflow, or perhaps was more full than today
only 1000 years ago, or perhaps has FAR more capacity than we imagine. (MWP, ancient warming periods.)
If we don’t know where the water is coming from, don’t know whether we can actually control the water level, don’t know if there’s a problem with the reservoir… to me it adds up to a lot of unknowns much in need of careful scientific work, and a lot less hyper-confident declarations that we know exactly what is going on. This really does look like the Y2K fiasco.
I for one much appreciate Craig’s paper as a good attempt to find some data that at least is consistent in measuring something about climate… just what we’re seeing is an interesting question.

407. Steve McIntyre
Posted Nov 18, 2007 at 7:17 AM | Permalink

#82. bender observes MWP drought in the US:

Is it possible that Loehles data and Ababnehs data are wholly consistent?

Lloyd and Graumlich connected foxtail widths to drought and temperature non-linearly. They are cited by the Team but the references do not support the use made of the data by the Team.

408. Posted Nov 18, 2007 at 7:47 AM | Permalink

Craig —
Your Figure 1 series at http://www.ncasi.org/programs/areas/climate/LoehleE&E2007.csv is greater than 0.3 during 1249-1255, but barely 0.1, if that, in the surrounding years. Did several series kick out in unison during that period?
If so, se’s would presumably show that uncertainty was just temporarily high during that episode, because of the small sample size. As is, your graph seems to say there was a clearcut 7-year heatwave at that time.

409. Steve McIntyre
Posted Nov 18, 2007 at 7:59 AM | Permalink

#82. Julien E-G objected: .

Yes, i did note that, and i find it very entertaining that when Caspar Amman is struggling with publication deadlines, it deserves a Wheres Caspar ? entire thread, but that when Steve McIntyre is busy, his army stands still to hear what he has to say because they cant form a judgment by themselves.
Julien

This thread has over 400 posts on it, so obviously people here were not “standing still” waiting to see what I thought about the paper. This was already true at the time that Julien made this post; in making posts to a blog, it’s a good idea to avoid making argumentative and untrue observations like this, which simply detract from the credibility of the author. I’ve responded to the Where’s Caspar comment on the other thread here.

410. Posted Nov 18, 2007 at 8:02 AM | Permalink

Re 322: Great map, Hans! But I only count 15 points. Do some overlay?
Again, I’d like to see these and other supplmentary materials on a webpage of Craig’s creation that would have more permanence than this little discussion. Speaking of which, Craig’s page should also provide a link to this thread (plus any extended at RC etc.)
A graph of each series, with its smoother as construted by Craig, would also be informative.

411. bender
Posted Nov 18, 2007 at 8:33 AM | Permalink

Re #412
Some of the proxies are entire regions, so they are painted gray instead of using red dots.

412. Hans Erren
Posted Nov 18, 2007 at 8:40 AM | Permalink

re 412:
Thanks, This is just the map from RichardT’s R-script. I haven’t found time to look at the original proxy list. I will make a better looking map when I find the time.

413. bender
Posted Nov 18, 2007 at 8:46 AM | Permalink

I verified the last 4 proxies on the list. (Was working them bottom-to-top when RichardT’s script appeared.)

414. EW
Posted Nov 18, 2007 at 9:00 AM | Permalink

And what about the Brazilian speleothem? It wasn’t suitable?

415. Bob Meyer
Posted Nov 18, 2007 at 9:07 AM | Permalink

Craig Loehle:

I wrote this in #362

Loehles claims are simple and modest: 1) there are differences between tree ring proxies and other proxies and 3) the non tree ring proxies strongly suggest that the LIA and MWP were real.

The only inferences that can be drawn are 1) tree rings and other proxies give different results and 2) it is plausible that the MWP existed, but we need more data. I hope these claims arent too hysterical and loud.

So if your intention was to get these points across to a non expert in the field, then I guess you succeeded in at least one case. (I also need to learn to count, it’s “1” then “2” not “1” then “3”)

PS Thanks for the article. It was clear, concise and a pleasure to read.

416. bender
Posted Nov 18, 2007 at 9:14 AM | Permalink

#416
Loehle will probably respond in a day or so. Meanwhile, it would be useful to make a full list of proxies that were not used but you think should have been used and get him to explain why in one shot. Because the obvious methodological question is “how were the proxies chosen?” “Were they cherry-picked?” He has given his answer, twice now. If you find his answer to be incomplete or imprecise then be patient. Rather than ask him to answer the same question 50 times, give him a chance to prepare a full rebuttal to the whole question, rather than proxy by proxy.

417. Jim Clarke
Posted Nov 18, 2007 at 9:16 AM | Permalink

Sod (#402),

I mentioned that no data shows a .4 degree warming for the years in question at the end of Loehle’s graph, to which you responded…

…you mean no temperature measurement apart from measuring the temperature shows that rapid increase?

(just by eyeball: 1980 sligthly below +0.2, and an endpoint slightly below +0.6)

The years in question are 1980-1995. The gistemp graph shows about a .2 degrees warming for those years and this, I believe, is the warmest of all the various temperature measurements. Certainly the satellites do not show as much warming and they are arguable more accurate. More importantly, the few updated proxy summaries I have seen do not show .4 C warming over those 15 years, which would be required for an apples to apples comparison with the Loehle graph. The bottom line is that data in this paper supports the statement that the MWP was warmer than late 20th century temperatures, no matter the statistical method one would use to derive the last 15 years of data. In several more decades, we may have non-treering proxy studies that indicate 21st century temperatures are warmer the the MWP, (although I personally doubt it). Until then, Loehle’s statment is scientifically accurate.

To all: “Why is the MWP important?”

I can not believe the sour-grapes arguments and the rationalizations that have surfaced ever since the ‘Hockey Stick’ flaws were revealed! For a scientist, the ultimate goal should be an understanding of climate and climate change. The understanding of any physical system begins and ends with data. Theory is derived from past data and confirmed with future data. This is a fundamental process in all science! Arguments that our understanding of past climate change is not important in the AGW debate indicates that science itself is no longer important in the debate, which seems to be precisely what is happening with the demand for CO2 regulation.

Secondly, the climate models, which are the primary ‘evidence’ given for an impending climate crisis, begin with the assumption that GHGs (particularly CO2) are the primary drivers of global climate change. We believe that the concentration of CO2 in the atmosphere was relatively stable for thousands of years before the industrial revolution. IF GHGs are stable, the models will predict a stable climate. If past climate fluctuated as much as the Loehle paper indicates, then the climate models are built on a false assumption, making their output meaningless. The brunt of the AGW argument then collapses, and immediate action on CO2 emissions becomes not only unwarranted, but extremely dangerous. (All pain, no gain!)

Finally, there has never been any question that increasing CO2 in the Earth’s atmosphere (all else being equal) would tend to increase lower atmospheric temperatures. The debate has always been over the magnatude of the impact. In order to quantify the affect of CO2, we must first quantify the affect of natural climate change variables. The IPCC assumes that past climate was realtively stable via Mannian reconstructions, and therefore concludes that these natural variables are very weak. If the Loehle reconstruction is accurate, then natural variables are much stronger than the IPCC assumes and would have to be considered as a much larger factor in recent temperature observations. Since all of the known natural climate variables would generate a (general) warming signal over the last 120 years, there would be very little left to attribute to CO2, once again deflating any argument for an impending climate crisis!

If the findings of the Loelhe paper are supported and verified by additional research, the foundations of the AGW argument are invalidated and the AGW theory (as it stands today) is falsified. That is why the MWP and LIA are important.

418. Craig Loehle
Posted Nov 18, 2007 at 9:24 AM | Permalink

Not being an insomniac, I am only now available to respond. Bender #366 thanks. Why did I pick conroy alke and not Hell’s kitchen? I do not remember finding the Hell’s kitchen data. Either I missed it (over a year ago when collecting the data), or it wasn’t posted at that time, or I thought there was something wrong with it. Since it does not ring a bell, I think I missed it.
The proxies are mostly calibrated to linear regressions (except the pollen, borehole, and phenology data). Are they subject to parabolic nonlinearities like we suspect tree rings are? Maybe. What I suggest is that since I had many proxies they would not all have the same flaws. This certainly needs investigation.
The MWP is important because it is implied by the hockey stick that the “normal” pattern of climate is flat, without major ups and downs. Therefore any big jump must be due to GHG.
How did I handle viau data every 100 years? One way is to connect the dots (interpolate) or use step functions. I decided that if he estimated the data every 100 years it is giving too much credit to spread it out over 100 years. I will do some plots later showing things change if you interpolate instead.

419. Craig Loehle
Posted Nov 18, 2007 at 9:46 AM | Permalink

The Brazillian data
ftp://ftp.ncdc.noaa.gov/pub/data/paleo/speleothem/southamerica/brazil/botuvera2005.txt
only has 16 points over the interval. Also, I only took series where the authors calibrated their proxy to temperature.
I very much would like a list of proxies I missed. I emailed maybe 6 authors about their data and didn’t get a reply, but maybe their data is posted now.

420. Susann
Posted Nov 18, 2007 at 10:07 AM | Permalink

Thanks for the tolerance I’ve experienced here so far. Sorry about my off-topic posts.

The Lohele reconstruction seems to be important because it addresses the question about the value of tree ring proxies in paleoclimate temperature reconstructions. I understand what taking the tree rings out of the data has shown — tree ring data does not show a MWP. The proxy measures used in Loehle do. I would think it preferable to develop a better understanding of tree rings and climate rather than ignoring the tree ring data because that has the appearance of rejecting data that fails to give the results one expects (just as including it gives the results one expects). As well, updating the existing tree ring data would seem important so that the effects of current warming and CO2 levels/ moisture etc. on tree growth are better appreciated (I understand Mr. McIntyre has already done this!)

The other contribution of Loehle seems to be the existene of a MWP, especially one possibly warmer than today. The existence of a MWP suggests that climate variances on a global scale are more common than was once imagined. That still leaves the question of the cause of today’s warming. The fact that warming occurred in the past is a given. The cause of today’s warming is the \$64,000 question. The back and forth between camps on the paleoclimate data, the “hockey stick” and MWP seems to be useful to a policy maker only to the extent that it induces a sense of caution about using paleoclimate temperature reconstructions to make policy (and to rouse the rabble.) It doesn’t answer the question of warming today or what, if anything, should be done.

421. Craig Loehle
Posted Nov 18, 2007 at 10:13 AM | Permalink

Susann, you are a quick study. Your 422 is dead on. The existence of the MWP does not answer the cause of the recent warming, but it does remove the assumption that GHG are the only possible cause, which is what is often asserted.

422. Stan
Posted Nov 18, 2007 at 10:24 AM | Permalink

GHG are not often asserted by climate scientists as the only possible cause. You are painting with too broad of a brush.

423. Larry
Posted Nov 18, 2007 at 10:25 AM | Permalink

The MWP is important for another reason. If it can be established that the earth was considerably warmer in the recent past (i.e. within recorded history), it knocks the legs out from under Hansen’s “tipping point” conjecture. The MWP is outright falsification of the more extreme disaster scenarios. I suspect that’s why it’s become something that has to be defended at any cost.

424. bender
Posted Nov 18, 2007 at 10:27 AM | Permalink

A warm MWP implies:
-an elusive “something else” may account for current warming “trend”
-current warming is not “unprecedented” (which proves there is an alarmist camp masquerading as scientists, unwilling to apply proper statistics to time-series inferences)
-the magnitude of the CO2 sensitivity coefficient (which almost everyone at CA agrees is non-zero) may be lower than what the IPCC “consensus” suggests
-the internal variability of terawatt heat engine Earth is not necessarily miniscule compared ot the external forcing, implying that the GCMs tunings may be off somewhat

If the Team truly wanted to address this question, they would re-run Li et al. (2007) without the active ingredients to which they are addicted – which is exactly what Loehle (2007) has tried to do.

425. Larry
Posted Nov 18, 2007 at 10:28 AM | Permalink

Again, this isn’t an “either-or” question; it’s a “how much” question. No rational person insists that AGW is all or nothing.

426. bender
Posted Nov 18, 2007 at 10:30 AM | Permalink

cross-post consensus!

427. Susann
Posted Nov 18, 2007 at 10:46 AM | Permalink

Finally, there has never been any question that increasing CO2 in the Earths atmosphere (all else being equal) would tend to increase lower atmospheric temperatures. The debate has always been over the magnatude of the impact. In order to quantify the affect of CO2, we must first quantify the affect of natural climate change variables. The IPCC assumes that past climate was realtively stable via Mannian reconstructions, and therefore concludes that these natural variables are very weak.

Is that an acurate description of the IPCC’s position on CO2/ GHG? That today’s warming must be caused by CO2/GHG because Mann’s reconstruction showed a relatively flat history? I thought that Mann’s reconstruction was more of a visual device to reinforce the dimensions of change today rather than the basis for the role of CO2 in current warming. In other words, sans Mann and the HS, the IPCC report would still be concerned about current warming and anthropogenic GHG.

If the Loehle reconstruction is accurate, then natural variables are much stronger than the IPCC assumes and would have to be considered as a much larger factor in recent temperature observations. Since all of the known natural climate variables would generate a (general) warming signal over the last 120 years, there would be very little left to attribute to CO2, once again deflating any argument for an impending climate crisis!

Couldn’t anthropogenic GHG magnify a natural forcer-induced change and lead to a crisis? Isn’t that what CO2 and CH4 have done during previous glacial/interglacial cycles? I.e. once the natural forcer kicks in, such as solar/obital, and GHG increases, the GHG acts as a feedback and futher increases warming. Thats what I understood. Is this incorrect?

428. Bob Meyer
Posted Nov 18, 2007 at 10:50 AM | Permalink

#425

Stan said:

“GHG are not often asserted by climate scientists as the only possible cause. You are painting with too broad of a brush.”

Yes, but they call the scientists who don’t assert this “denialists” or “shills for the oil industry”.

429. Judith Curry
Posted Nov 18, 2007 at 10:57 AM | Permalink

Craig, my understanding of the Mannian perspective is that they do not deny the existence of the MWP as an influence on North Atlantic climate (and western Europe, eastern U.S.), but rather deny that there is a global signal from the MWP. Most of your data samples come from the region that is directly influenced by the North Atlantic Ocean, with few points outside this region in the southern hemisphere or in the Pacific region. Analysis of these regions separately would help address this issue. I agree with JEG and others that we can learn much from regional analysis, and this may be the thing to focus on in the short term, given the relatively sparse sampling of the proxy data sets.

Craig, plaudits for engaging in the process here, you certainly appear to be an interesting thinker and scientist. The climate field needs new blood (both young climate scientists such as JEG and established scientists from other fields such as yourself). For your next publication on this topic that takes into account the good suggestions made on this thread, I hope you find a better journal than Energy and Environment, perhaps the EGU Climate of the Past journal.

First, I am very surprised that GRL did not send your paper out for review. I know that Science and Nature only send out a small fraction of papers for review, but this is the first I have heard (comments from others?) of a paper that is apparently otherwise compliant (in terms of topic, length, etc.) being sent back by GRL without review. This issue with regards to your paper should be investigated.

The journal Energy and Environment is found in only a few libraries worldwide. And the journal is not included in Journal Citation Reports, which lists the impact factors for the top 6000 peer-reviewed journals. Hence the scientific impact factor of this journal is negligible but in the past few years the “political” impact has been high since this journal is developing the reputation of being a journal skeptics can go to when they are rejected by the mainstream peer-reviewed science publications. And there seems to be a tendency to publish some very marginal papers simply because they are skeptical of anthropogenic climate change. The journal may be well suited for a review essay such as that written by David Holland, but a basic science paper will be will be pretty much unread and also tarnished by its publication in this journal. Without its exposure on climateaudit, the paper probably wouldn’t get much notice.

For a serious scientist and eloquent writer such as yourself, I hope that you will keep trying to publish future research on this topic in more mainstream and higher impact journals.

430. Larry
Posted Nov 18, 2007 at 10:59 AM | Permalink

Couldnt anthropogenic GHG magnify a natural forcer-induced change and lead to a crisis?

No. Feedbacks act as a consequence of temperature, and can magnify a forcing, natural or otherwise. Anthropogenic forcing can add to natural forcing. No one has claimed that GHGs change the climate sensitivity. The closest thing to that is Hansen’s conjecture on non-linear feedback, which is pure blue-sky speculation.

431. jae
Posted Nov 18, 2007 at 11:02 AM | Permalink

430:

Couldnt anthropogenic GHG magnify a natural forcer-induced change and lead to a crisis? Isnt that what CO2 and CH4 have done during previous glacial/interglacial cycles? I.e. once the natural forcer kicks in, such as solar/obital, and GHG increases, the GHG acts as a feedback and futher increases warming. Thats what I understood. Is this incorrect?

You should go to Unthreaded for this discussion, if you are really interested. I don’t think any of that has been demonstrated. It’s a hypothesis, but the empirical evidence contradicts it. The CO2 during past epochs LAGS temperature changes by about 800 years. It appears to be an effect, not a cause. There’s lots of information on this subject in the various threads here.

432. jae
Posted Nov 18, 2007 at 11:06 AM | Permalink

433: Judith, I think that is pure snobbery. There’s as much junk in the “mainstream” journals as there is in EE, and this is well-proven by this blog.

433. Larry
Posted Nov 18, 2007 at 11:06 AM | Permalink

Sorry, but I have to say it. Please ignore the feedback denier.

434. rhodeymark
Posted Nov 18, 2007 at 11:07 AM | Permalink

GHG are not often asserted by climate scientists as the only possible cause.

No – but they are happy to ignore that conclusion-without-qualification by their proxy in the media. Or are you unaware of the absolute hysterical tone of the current reports coming out of Valencia? Amazingly enough, GHG reduction is asserted to be the only “remedy”, and time is running out (and they really really mean it this time!).

435. Roger Dueck
Posted Nov 18, 2007 at 11:14 AM | Permalink

Judith #433 says

Most of your data samples come from the region that is directly influenced by the North Atlantic Ocean, with few points outside this region in the southern hemisphere or in the Pacific region.

Six of fifteen occur outside of the “North Atlantic” so nine occur in the region, I guess that qualifies as “most”. That’s a bit of spin, don’t you think, Judith? It appears to me that the analysis is robust through all data sets, unlike the Hockey Stick. Let’s give Mann the same level of scrutiny, shall we?

436. windansea
Posted Nov 18, 2007 at 11:22 AM | Permalink

Craig, my understanding of the Mannian perspective is that they do not deny the existence of the MWP as an influence on North Atlantic climate (and western Europe, eastern U.S.), but rather deny that there is a global signal from the MWP. Most of your data samples come from the region that is directly influenced by the North Atlantic Ocean, with few points outside this region in the southern hemisphere or in the Pacific region.

1. perhaps you missed the “where’s waldo” threads, most of the GISS warming appears to be regional (NE hemisphere)

2. AGW proponents either minimize temps of MWP or dismiss it as regional, there are proxy studies from all 7 continents listed at CO2 science that show a strong MWP signal equal or greater than the CWP. I don’t know how many of these studies meet Craig’s paramaters.

http://www.co2science.org/scripts/CO2ScienceB2C/data/mwp/mwpp.jsp

2.

437. Posted Nov 18, 2007 at 11:26 AM | Permalink

A few people have commented on the journal, Energy & Environment, in which Craig’s paper was published. The journal’s reputation has sometimes been questioned, because it has published papers without full peer review. (I think that one/both of the McIntyre & McKitrick papers that appeared in E&E did not have full review; Steve M. can confirm or correct this.)

As Craig has noted, though, his paper did go through a regular, even thorough, peer review. Yet there is a paper in the same issue by David Henderson, which David tells me, did not go through peer review. Then again, I have a paper in the issue (mentioned on ClimateAudit here), and it had a regular-to-thorough peer review.

Ultimately, then, the journal’s peer reviewing is done at the editor’s discretion. My view is that this is fine. Peer review can lead to improved papers, but it is nowhere near all that it is advertised to be. Perhaps it would be a little better for the journal to indicate which papers were peer reviewed and which were not.

438. S. Hales
Posted Nov 18, 2007 at 11:28 AM | Permalink

Just some general comments: Craig’s data show that global temperature anomalies switch between apx. +/- .6C and his reconstruction anomalies are evenly distributed above and below 0. Mann’s reconstruction is skewed to the negative. I am unsure what the meaning of this is but if climate has regular cycles then a reconstruction should show regular patterns when the time series is sorted from high to low values. If it does not then perhaps the reconstruction is not accurately capturing variability.

Also, 40% of his sites are not influenced by the NAO.

439. Clayton B.
Posted Nov 18, 2007 at 11:36 AM | Permalink

Would it be appropriate to delete the values on the y-axis for these types of plots?

440. Craig Loehle
Posted Nov 18, 2007 at 11:36 AM | Permalink

While some hockey stick builders don’t deny that the MWP exists (some do deny it) they say it either was a minor blip or strictly regional. Mann argued that peaks in different places don’t line up in time, hence it is not real. this ignores both sample error and dating error, of course.
At this point I don’t care much about reputation vis a vis E&E status. It was important to get it out there. Now I plan to redo it in more detail.
Also, please note the dozens of basic geology papers that drilled a core or something, and just plot the data over time. No hypothesis tests, just a plot. Isn’t that science too? I would have thought so.

441. richardT
Posted Nov 18, 2007 at 11:40 AM | Permalink

We desperately need to see the individual reconstructions to move this debate on. Has anybody written R code to import and graph the data. I’ve done the first four, but now have to write a lecture. Please can somebody contribute the others.
#1) GRIP borehole 18O temperature (Dahl-Jensen et al., 1998); grip

442. richardT
Posted Nov 18, 2007 at 11:53 AM | Permalink

The curse of the < strikes again!
#1) GRIP borehole 18O temperature (Dahl-Jensen et al., 1998); grip=read.table("http://www.climate2003.com/data/moberg/djgrip.txt", header=T)#BP2000? #2) Conroy Lake pollen (Gajewski, 1988); conroy=read.table("ftp://ftp.ncdc.noaa.gov/pub/data/paleo/pollen/recons/liadata.txt", skip=50, nrow=68)[,1:2]#BP1975! hells=read.table("ftp://ftp.ncdc.noaa.gov/pub/data/paleo/pollen/recons/liadata.txt",skip=225,nrow=75)[,1:2] clear=read.table("ftp://ftp.ncdc.noaa.gov/pub/data/paleo/pollen/recons/liadata.txt",skip=176,nrow=48)[,1:2] plot(hells, col=2, type="l", ylim=range(c(hells[,2],conroy[,2], clear[,2]))) lines(conroy, col=3) lines(clear, col=4) #3) Chesapeake Bay Mg/Ca (Cronin et al., 2003); ches1=readLines("ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/cronin2003/cronin2003.txt")[78:527] #year AD ches=t(sapply(ches1,function(r)as.numeric(strsplit(r,"[[:space:]]+")[[1]][c(3,5)]))) rownames(ches)

443. Stan
Posted Nov 18, 2007 at 11:55 AM | Permalink

#431

Bob – People whose work has been disparaged on this site do not think it is all greenhouse gases. The broad B&W painting of people and their work is not close to correct. This is off topic, sorry.

444. Steve McIntyre
Posted Nov 18, 2007 at 11:59 AM | Permalink

Yes. I’ve collated and plotted probable versions of the series. I’ll post them up right away.

I’ve obviously spent a lot of time on individual series in different proxy reconstructions. The first 8 series are all used in Moberg and constitute the majority of his low-frequency series. May I observe the irony of Richard T (whose comments I value) taking an interest in Loehle proxies purporting to show an MWP, while seemingly not taking a similar interest in prior studies of a similar nature.

445. steven mosher
Posted Nov 18, 2007 at 12:19 PM | Permalink

RE 432. Sounds like Dr. Curry is volunteering to co-author or volunteering JEG.

All kidding aside. On the issue of a global signal for the MWP. What kind of sample
distribution would satisfy folks? And, do we see any other example of a persistent ( decades long)
trend that is purely regional?

446. Bob Meyer
Posted Nov 18, 2007 at 12:21 PM | Permalink

#446

Stan – I was just teasing. Maybe I need to start using smileys.

447. DocMartyn
Posted Nov 18, 2007 at 12:22 PM | Permalink

Craig can you do me a favor? Pick exactly half of your data sets at random and then multiply them by -1. Then repeat your analysis.If you are in luck you should find that you have a data set that consists of noise, you should also be able to statistically measure your varience from the mean at different time points. Just doing it on one random set will show the validity of this approach. You could use 200 different random picks of which half you are going to invert, to give you a real ‘zero” signal at time=t and the SD at time=t.

448. Posted Nov 18, 2007 at 12:28 PM | Permalink

Hu,

Craig (#73, 178, 214) questions how to do this when his proxies have divergent or even unreported measurement errors themselves. This is a good question, but turns out not to be a big problem. Suppose we have n observations y_i = mu + e_i, but var(e_i) = v_i, which is different for every observation but unobserved. Craig is estimating mu with the simple average y-bar. Assuming independence, var(y-bar) = (1/n^2)Sum(v_i). As long as the v_is are not too wildly distributed, Sum(v_i) is consistently estimated by the Sum of Squared Residuals SSR = Sum(y_i – y-bar)^2. Therefore the traditional formula sqrt(SSR/(n*(n-1)) will consistently estimate the standard deviation of y-bar about mu, and will provide
asymptotically N(0,1) t-tests (or z-tests if you prefer) for hypotheses.

If I got it correctly, this time we have local temperature recons, and from RC I read that only a small number of stations is needed to calculate global temp anomaly. Let’s say 18, and assume that all those series used in Craig’s paper are exact (perfect local temp). In this case, your method would overestimate uncertainties (negatively correlated errors). Overestimation of uncertainties is unprecedented in climate reconstructions. Spatial sampling comes into play with local reconstructions, teleconnections make things easier.

Now, where did JEG go? Went to check how MBH99 CIs were calculated, and will never come back?

449. trevor
Posted Nov 18, 2007 at 12:38 PM | Permalink

Re #422: Susann. You say:

The Lohele reconstruction seems to be important because it addresses the question about the value of tree ring proxies in paleoclimate temperature reconstructions. I understand what taking the tree rings out of the data has shown  tree ring data does not show a MWP. The proxy measures used in Loehle do. I would think it preferable to develop a better understanding of tree rings and climate rather than ignoring the tree ring data because that has the appearance of rejecting data that fails to give the results one expects (just as including it gives the results one expects). As well, updating the existing tree ring data would seem important so that the effects of current warming and CO2 levels/ moisture etc. on tree growth are better appreciated (I understand Mr. McIntyre has already done this!)

It seems that you are new here, otherwise you would not make such a statement.

The issue with the Hockeystick is not that tree ring studies do not show the MWP – quite a few do in fact. The issue is that it appears that the tree series have been ‘cherry-picked’ such that series inconveniently showing a MWP have been excluded. As well, the novel procedures used have been shown to extract a ‘Hockeystick’ shape from pretty much any data series evaluated. Finally, the proponents seem to have knowingly ignored standard statistical tests that show that the Hockeystick produced has little or no skill.

As you can see, the issues are rather different than you characterise them.

450. richardT
Posted Nov 18, 2007 at 1:03 PM | Permalink

#447
I am only requesting data that should have been in the supplementary info of the paper. Without seeing the data, their resolution and their last observation, it is not possible to evaluate the reconstruction.

451. Posted Nov 18, 2007 at 1:10 PM | Permalink

RE: 111

The Loehle and Mann graphs are critically different in two of the most important respects that are at issue in this debate about hockey sticks and proxies. Loehle captures the tail end of the MWP but Mann eliminates it. Loehele shows a deep LIA; Mann flattens it. The only similarity is the 20th century warming. Loehle destroys Mann’s contention that the 20th century warming is unique in a thousand years and by bringing out the LIA demonstrates the high degree of the natural variability of climate which Mann got rid of.

452. Craig Loehle
Posted Nov 18, 2007 at 1:33 PM | Permalink

Steve M has posted most of the data I will be updating this as quickly as possible.

453. Rob
Posted Nov 18, 2007 at 1:42 PM | Permalink

“Is that an acurate description of the IPCCs position on CO2/ GHG? That todays warming must be caused by CO2/GHG…”

IPCC released “the Summary for Policymakers of the AR4 Synthesis” yesterday(11/18).
Their position on the GHG issue is pretty much manifested in there.

It’s online at there site…
http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr_spm.pdf

/Rob

454. Susann
Posted Nov 18, 2007 at 1:43 PM | Permalink

Trevor

It seems that you are new here, otherwise you would not make such a statement.

I’ve read here on and off, but I haven’t posted, in part because climate science is new to me (I’m more of an environmental health policy type) and I’ve only just read up on the debates in prep for a course on policy analysis starting after Christmas. (I plan on looking at this issue – wish me luck!) I haven’t read every post, but is there really such consensus here on all the issues that no one would make such a statement except a neube? What happens to them if they do? I thought this place welcomed open-minded discussions.

The issue with the Hockeystick is not that tree ring studies do not show the MWP – quite a few do in fact. The issue is that it appears that the tree series have been cherry-picked such that series inconveniently showing a MWP have been excluded.

I didn’t know that — was a reason given why? Or was this an after-the-fact admission? I thought all the tree ring data was used in MBH.

As well, the novel procedures used have been shown to extract a Hockeystick shape from pretty much any data series evaluated. Finally, the proponents seem to have knowingly ignored standard statistical tests that show that the Hockeystick produced has little or no skill.

Of that I was aware, which I see as the main contribution of Mr. McIntyre’s work. I have read up on the basic “hockey stick” debate, but I am only now digging into the specifics, like proxy use.

The more I do, the more I feel that paleoclimate global temp. reconstrutions are quite unreliable as policy tools other than to make the point that climate has changed in the past. What proxies should be used? How many are enough to produce reliable results? What statistical methods should be employed to analyse them? And most importantly, what can they say about current warming?

455. Peter D. Tillman
Posted Nov 18, 2007 at 1:48 PM | Permalink

Re #420, 421 proxies considered and rejected; proxies to add for the next study

Craig: I think you would be wise to keep a set of detailed notes on what proxies you considered and rejected (and why), to deal with the inevitable charges of cherry-picking. You may even want to post this with your supplementary material.

I see you are already starting a list of other proxies to add to your initial study. Good.

And thanks for a nice piece of work, that is already starting some interesting discussions. I’ll be interested to see how your work develops. I agree with Dr. Curry (#432) — for the next study, try for a mainstream journal, even if this slows publication. I’m sure the CA crew would be happy to preview your next paper, and/or help deal with reviewer’s comments.

Best regards,
Peter D. Tillman

456. Timo
Posted Nov 18, 2007 at 1:52 PM | Permalink

Craig,

I have been reading your paper during the weekend. Very interesting and convincing, despite some questions being raised in this thread. I am of the opinion that not the number of proxies is relevant, but the reliability of the proxy and methods used. A few realiable data covering the Earth (surface) can tell a clear story.

I am a layman in this field of science, so I will not interfer in the technical discussions. However, I am interested in the background of a particular statement in your paper. You state: “In a few cases, data that were appropriate could not be obtained from authors”.

Can you elaborate why this information was not available and if these data were or could be of importance for your paper?

457. trevor
Posted Nov 18, 2007 at 1:55 PM | Permalink

Re #457: Susann.

I havent read every post, but is there really such consensus here on all the issues that no one would make such a statement except a neube? What happens to them if they do? I thought this place welcomed open-minded discussions.

Sincere apologies. I have been lurking here pretty much since the earliest days, and had thought that the issues relating to the Hockeystick had been pretty much settled and indeed, that there was ‘consensus’. My bad.

458. Judith Curry
Posted Nov 18, 2007 at 1:59 PM | Permalink

Re E&E. The reputation of a journal rests in the number of citations it receives, the scientific stature of its editorial board, ts reputation for fair and critical reviews of papers, and its selectivity. E&E scores very low on all of these (with possible exception of the review process, i simply don’t know). Further, based upon their public statements, many of the editors of E&E have an overt agenda with respect to energy and environmental politics. Hence choosing to publish a scientific paper in this journal taints the paper and the author as being driven by a political rather than a scientific agenda.

Peer review is no panacea, and no guarantee of anything. Peer review supervised by an editorial board without strong scientific reputations and an overt political agenda (as reflected by public statements by the editors) means little more than that the paper passed some sort of “litmus” test. Peer review supervised by an editorial board with strong scientific reputations and no overt agenda (as reflected by their public statements or lack thereof) guarantees nothing more than that the paper is original, moves the science forward, and is free of obvious methodological errors.

Personally, if i had a paper that I was unable to publish in one of the mainstream journals, I would select a lower impact, online journal that is not associated with a political agenda, something like ArXiv. IMO, it is better to simply publish scientific paper on your own website (or the journal of climateaudit) than E&E. My issue with E&E isn’t snobbery, it is the overt political agenda of much of the editorial board and the journal’s reputation as a refuge for people who can’t get published anywhere esle that results in papers (and authors) being ignored or dismissed by other scientists simply because of the journal in which it was published. IMO, serious scientific papers on the subject of climate change should seek another publication venue besides E&E. I hope that SteveM’s future publications end up somewhere else.

With regards to the MWP. There are two broad issues: a scientific one (regarding how temperature across the globe has changed and to what extend the MWP was a global phenomena) and a political one (associated with debunking the hockey stick owing to its importance in the IPCC reports and its policy implications). The strategies for addressing these two MWP issues is somewhat different. Attempts to falsify the hockey stick by pointing out methodological errors can be useful in two ways: sowing uncertainty about AGW, and in pointing the way to a better understanding of the global temperature record on milennial time scales. At this point, the challenge is to move the science forward. This can only be accomplished by interpreting the complete collection of proxy time series based upon the individual proxy sensitivity to climate variations and the regional coherency of different proxy types. Based upon the extensive data assembly efforts being undertaken by SteveM and others on this site, you have the potential to make an important contribution to moving the science forward (which requires some coherency and understanding of the regional climate variations, no way around it).

459. Larry
Posted Nov 18, 2007 at 2:16 PM | Permalink

Susann,

I didnt know that  was a reason given why? Or was this an after-the-fact admission? I thought all the tree ring data was used in MBH.

This is where you have to keep your eye on the ball. It’s not done explicitly; it’s inherent in the computer code that Mann et. al. used. That was the primary point of the McIntyre-McKintrick critique of the hockey stick.

The reason why there appears to be a “consensus” here is that there’s a lot of background that isn’t obvious in the specific threads. It’s not going to be obvious to a noob. I haven’t been here that long, and a lot of the esoterica still eludes me.

This place does have a learning curve. I hope people aren’t rude to others on the learning curve, but some will be, intentionally or not.

460. Susann
Posted Nov 18, 2007 at 2:19 PM | Permalink

Sincere apologies. I have been lurking here pretty much since the earliest days, and had thought that the issues relating to the Hockeystick had been pretty much settled and indeed, that there was consensus. My bad.

The issue as I see it is not the hockey stick, which I accept has been settled. The hockey stick graph, from what I can see, has become a lumpy snake, with a MWP and LIA, plus late 20th c. warming.

The issue is the MWP and what it means to the debate about current warming. Loehle does not use tree ring data, and the result is a clear MWP that appears global. The existence of a MWP suggests that such a warming on a global scale has happened at least once since the start of the last interglacial and is not unprecedented. It seems that debate remains on the implications of this for our understanding of current warming.

This is where I am not clear. If we are in a similar period of natural warming, how will the anthropgenic GHG we have produced since the late 19th c. affect the degree of warming we will experience? What is at work in the current warming? How much of it is due to natural forcers (and what are they?) and how much to anthropogenic GHG? How will the doubling of GHG affect any natural forcing?

This is a critical question for policy analysis — we can’t make good policy decisions if we have bad science.

461. Larry
Posted Nov 18, 2007 at 2:29 PM | Permalink

463, what you’re after is the elusive value of the climate sensitivity. That’s the temperature rise expected from a doubling of CO2. AR4 fixed the range as somewhere between 1.5 and 4.5 C. This study suggests that it’s closer to the lower end of that range. But with so many confounding factors, it’s not as if we can calculate a new upper limit.

There are a long list of other issues that enter into the issue of remedies, but that all hinges on that number (and, of course, the scenarios, themselves).

462. Susann
Posted Nov 18, 2007 at 2:31 PM | Permalink

That was the primary point of the McIntyre-McKintrick critique of the hockey stick.

Sorry to go over already-tilled ground, and I will stop after this, but mea culpa for I understood the hockey stick to be about an improper use of PCA, leading to a hockey stick shape no mater what the data. I also thought it was the use of tree ring data, which does not accurately reflect temperature change — the Bristlecone Pine data. I hadn’t realized that there was cherry picking involved in the data itself. I thought that was an accusation launched back at MM.

It’s very complex. Will there be a test? 🙂

463. Jaye
Posted Nov 18, 2007 at 2:40 PM | Permalink

Hence choosing to publish a scientific paper in this journal taints the paper and the author as being driven by a political rather than a scientific agenda.

Based on the events of the last 5-8 years same statement applies to Nature and Science.

464. Larry
Posted Nov 18, 2007 at 2:45 PM | Permalink

465, someone more up-to-speed on the details is going to have to explain the several issues with the HS, but the “cherry picking”, as I understand it, was automatic, and quite possibly inadvertent. I don’t believe that the issue was ever explicit manual selection. But I’d like someone here with more familiarity to confirm/deny/fill in the holes.

465. Susann
Posted Nov 18, 2007 at 2:54 PM | Permalink

Larry, that’s OK, I realize the HS has been done to death here. I can read archives.

466. John F. Pittman
Posted Nov 18, 2007 at 3:48 PM | Permalink

Dr. Loehle, I was wondering if the data could be decompressed to annual resolution using appropriate method(s)/assumption(s) (audio and graphics have some interesting routines), and recomputed as an average for the series; and then plot an end of your composite, and “splice” (in a different weight/color) temperature anomalies (deviations) to 2000+? When I look at your data from century to century, I agree with other posters, I am not sure where/how the interpolation and the averaging have taken place. I understand that this would worsen the request of confidence intervals that some have requested. However, I believe these are two separate issues.

I would refine using the ~40% not influenced by NAO to a series, 0% NAO to 100% NAO. First would be the ~40% not influenced NAO, then increase the non-NAO by 1,3,…, all NAO. Compare and determine if there is an appreciable statistical difference in the series.

I just caught up after only 1 1/2 days and it was a bit of reading. However, I was impressed by the number and reasoning of those who wish to understand how the interpolation/averaging/selection of proxies could effect the MWP. I think the decompression and series would help a lot on this.

Finally, thank you for an approach that questions obvious “cherry picking”. One of my degrees is in biology; and I never got educated on “teleconnections”. Several other biologists have complained in other threads of this particular assumption. I found LEG’s comments particularly uninformed/biased.

How is each proxy representative of a particular area ? What is its geographical weight in the final mean series ?

I know that this may be an old argument for you and all, but I do not recall a verification/validation that the Mann’s (or any other’s) proxies were representative to a typical area with respect to LEG’s statement about “representative of a particular area” much less “its geographical weight in the final “mean” series”. Perhaps all are atypical, although they are particular; likewise, they may not be geographical. It was shown that one area of the US was a sweet spot for the entire world, according to Mann, is there some intrinsic value/relationship for your paper as well?

Perhaps LEG, rather than you, should validate/verify, AND POST, what this intrinsic value/relationship is? That way the rest of us could examine it as well. I was satisfied with your reasoning, but I am sure any details of quandries you considered while your wrote your paper wrt area vs geographic interpretations would be appreciated.

you are effectively using a statistical model, and are not exempt from the verification exercise

As pointed out above, I find it strange, somewhat, that someone familair with Mann, such as LEG, would be talking of verification with the “censored” file of Mann, part of the historical record. But I wonder, that when you get the time, could you examine this verification/validation question in light of your works. What verification/validation do you think is appropriate and why? I realize that the assumption of no, or little tree-rings tends to preclude this type of question, or should, but still I believe that examining what you consider an appropriate verification/validation sequence would be an enlightening conversation.

467. fFreddy
Posted Nov 18, 2007 at 3:48 PM | Permalink

Susann, the pseudo-PCA of MBH is an automatic cherry-picker of any input data series that happened to be hockey stick shaped.
If there are no “hockey sticky” inputs, then the output is not “hockey sticky”.
The manual cherry picking lies in ensuring that at least some of the input data are “sticky”.
Generally this means the bristlecone pines, or a few other data series with highly “sticky” shapes; there are also some reconstructions whose inputs actually include the output from MBH98/99.

468. Jean S
Posted Nov 18, 2007 at 3:53 PM | Permalink

Judith:

My issue with E&E isnt snobbery, it is the overt political agenda of much of the editorial board and the journals reputation as a refuge for people who cant get published anywhere esle

Do you have a similar issue with Climatic Change? For an outsider, it seems to be the E&E equivalent in the other end of the spectrum.

469. Bob Meyer
Posted Nov 18, 2007 at 3:57 PM | Permalink

Re 461

Judith:

It wouldn’t matter to me if Craig’s work were published in The Weekly Standard, Salon, Mad Magazine or The Satanic Gazette, it is still a clear, concise work that will no doubt provoke a great deal of controversy and hopefully, some continued research in this area. It is more a reflection on the periodicals that didn’t publish his work than E&E is a reflection on the quality of Craig’s paper.

Perhaps you are more concerned with the effect of Craig’s paper on E&E’s reputation rather than vice-versa. If well thought out contrarian works have no venue other than “biased” publications then what does that say about the mainstream periodicals? While their reputations would be tarnished by their failure to recognize the value of Craig’s work, E&E’s reputation would be enhanced thereby producing greater interest in their other articles. The consensus publication monopoly would be broken forcing them to a higher standard in their articles in order to meet their competition.

Unfortunately for many consensus-ists it would mean that their statements on AGW would no longer have the quality of ex-cathedra pronouncements and they would be forced to run a gauntlet of criticism far more severe than the “home town” peer reviews they now experience.

The ultimate criteria for scientific works must be fidelity to the real world, not the “respectability” of the periodicals in which they are published.

470. Gerald Machnee
Posted Nov 18, 2007 at 4:01 PM | Permalink

RE #463 – **This is where I am not clear. If we are in a similar period of natural warming, how will the anthropgenic GHG we have produced since the late 19th c. affect the degree of warming we will experience? What is at work in the current warming? How much of it is due to natural forcers (and what are they?) and how much to anthropogenic GHG? How will the doubling of GHG affect any natural forcing?**
Those are the questions to ask when someone tells you the “science is in”. Steve M is waiting for an answer to the detailed calculation of climate sensitivity as Larry stated it in #464.
This blog is about verifying or duplicating results. That is difficult when researchers do not archive data.
Similarly there are no direct measurements of the amount or percent of the temperature change caused by GHG or CO2.

471. steven mosher
Posted Nov 18, 2007 at 4:20 PM | Permalink

RE 471.

All of Dr. Curry’s comments have to do with the SOCIOLOGY of science. Not the accuracy.
As a Kuhnian I see her point. If E&E published that “2+2=4” I am sure that some would
question the truth value of the proposition.

OTOH, the point of publishing Complete data, sources and methods is to REMOVE
the following biases.

1. Observer bias.
2. Patron bias.

If E&E and Dr. Loehle publish data and methods, then the scientific method will handle any bias
Dr. Loehle may have and any bias his “patron” may have.

The sociological BIAS is not so easily correctable. As Dr. Curry notes you need an unspecified number
of “citations” and unspecifiable “scientific stature” Basically “boys club” stuff, dressed up in fancy
language.

Truth be told. Dr. Curry is giving good pragmatic advice. It’s not about the science. It’s not
about the truth value of the proposition.

472. Larry
Posted Nov 18, 2007 at 4:28 PM | Permalink

475, it’s broader than science. The only thing that keeps the NYT in business is the brand recognition that gives them a hold on certain people. If it were about merit of content, they’d have gone under years ago.

473. Susann
Posted Nov 18, 2007 at 4:29 PM | Permalink

This blog is about verifying or duplicating results. That is difficult when researchers do not archive data.
Similarly there are no direct measurements of the amount or percent of the temperature change caused by GHG or CO2.

OK — understood. I assumed there was more to CA than that but I haven’t read every post and didn’t realize that discussions beyond that were not encouraged. I’m glad to see verification and duplication, for both are necessary to produce confidence in the science so that policy makers can use the best science to make decisions. Since my interest in in what all this means for policy development, I’ll keep that in mind.

474. Craig Loehle
Posted Nov 18, 2007 at 4:47 PM | Permalink

Re Judith Curry and E&E reputation. All that Judith says is correct to a point. How do you tell bias? After an extensive publishing career (go ahead, google me) I can tell. I have submitted mainstream papers that got a few nitpicks or were accepted with no revisions. I have submitted novel papers (but not contrarian) and I got some review comments that didnt understand it. I have submitted papers where I didnt explain myself very well and had to work on it more. On the other hand, with contrarian papers I have always gotten nasty reviews, ad hominim attacks, and reviews that in their totality consisted of this is the worst **** I have ever seen or you cant do this type of analysis with no explanation or justification, as well as the journal simply refusing to review it. The idea that E&E is biased but Nature and Climatic Change are not is simply not correct. The bias on this issue is right out in the open, and is mostly to totally prevent contrarian work from coming out. Remember the controversy over the Soon and Baliunas work a few years ago and people trying to get denialists fired. So, let us just say that this paper opens the door to further work, and speed was important rather than impact factor.

Timo asked why data were not provided when I asked authors for it. Either the authors did not yet have it put together, or didnt know who I was, or were too busy, or like to keep the data to themselves, or whatever. I dont know. The importance is that more data would make a better analysis.

John Pittman asked about data decompression to annualI dont understand this but John the data will all be available shortly and you can try it. He also asked about representativeness of the data. I have no idea how to assess the extent to which a particular site is representative or a region. The best solution to this question is to increase the sample size and show that no particular samples unduly influence the result.

475. RomanM
Posted Nov 18, 2007 at 5:02 PM | Permalink

After reading some of posts on this blog asking for error bounds (jeg) and whether the sites were global enough (Dr. Judith), I decided to do a little experimentation and find the ideal proxy reconstruction”. So, I took the global coordinates of the fifteen sites shown on the map, went to the GISS site on the web and located the closest weather station for each of the sites (I actually cheated a bit by taking the second closest for Conroy since the station there had a longer history). Each station gave me a proxy temperature reconstruction (a yearly mean temperature) over some of the time period from 1881 to 2006. Some of the records were very short (one was 11 years  probably not the one used in the original temperature reconstruction for that site). I then turned each of these into anomalies by subtracting the mean over the entire available record for each site. All anomalies available for a given year were then averaged for the ideal reconstruction (Yes, I know that isnt the optimal way to do things  it took long enough to do this as it was.). There was no attempt to fill in the missing values or balance the estimate for the different numbers of sites used in given years. It turned out that the resulting average of anomalies had a mean other than 0 so the sequence had to be re-centered. The GISS site provided the global and northern hemisphere records. These were both re-centered to have a mean of 0 also. The results were then plotted:

If you cant see the graph, you can find it here. Despite the fact that the data was not improved, the fit between the reconstruction and the GISS results is pretty good. It should provide Dr. J. with some comfort about the ability of these sites to represent the global situation to some extent. The correlation with the global temperatures is .76 and with the NH is .79. The higher variability in the graph for the earlier years has a lot to do with the fact that fewer records were available for the averaging process.
Why do I call this an ideal reconstruction? Because, instead of having to estimate the temperatures from proxies, I use the measured temperatures themselves and the real proxies would be unable to do better . Unless one believes that through teleconnection, a proxy can actually do better than thermometers, this type of approach provides a way to estimate a lower bound on the variability of any proxy using a given set of sites. The root mean square errors of the estimated global and NH temperature anomalies were about .34 C and .31 C respectively. It seems reasonable that any reconstruction using these sites would have a standard error (probably much) larger than that because of the increased uncertainty in estimating the local temperature. I would think that under the circumstances, the Manns standard error of .2C for estimates almost 1000 years ago seems a trifle optimistic.

476. Craig Loehle
Posted Nov 18, 2007 at 5:06 PM | Permalink

Roman M: Excellent! thank you. Some very clever people here!

477. steven mosher
Posted Nov 18, 2007 at 5:14 PM | Permalink

RE 476.

Susann. I would hazard that most folks here would not object to mitigation policies.

Simple example: if you suspect that GW or AGW is true then promoting settlement of humans
in places that are prone to inundation is not good policy.

Tax Malibu. Don’t rebuild NOLA.

Move everyone to kansas. ( the last was a joke.. cruel joke I know)

478. steven mosher
Posted Nov 18, 2007 at 5:26 PM | Permalink

re 478. HA. good one romanM.

You know when Hansen correlates one station wth another ( at 1200km) the corelation is .6 in the NH
and .5 in the SH.

479. fFreddy
Posted Nov 18, 2007 at 5:54 PM | Permalink

Re #480, Steven Mosher

I would hazard that most folks here would not object to mitigation policies.

The “mitigation policy” which seems most likely to happen first – based on the large companies agitating for subsidies to do it – is CO2 sequestration, which strikes me as the most utterly idiotic waste of money. So, with respect, I must beg to differ.

480. Bob Meyer
Posted Nov 18, 2007 at 6:02 PM | Permalink

Re 478

Wow! That is really impressive. Thanks.

481. Pat Keating
Posted Nov 18, 2007 at 6:12 PM | Permalink

477 Craig

I have submitted novel papers (but not contrarian) and I got some review comments that didnt understand it.

I had one novel paper (not in this field) reviewed by 2 referees. One said the main thesis wasn’t true, the other said it was already well-known!

482. steven mosher
Posted Nov 18, 2007 at 6:25 PM | Permalink

RE 483. Ffreddy. Hence my qualifier “most people”. we should not cluuter this thread with policy. MY bad.

483. Posted Nov 18, 2007 at 6:27 PM | Permalink

# 464

Judith Curry,

Thank you… 🙂

484. steven mosher
Posted Nov 18, 2007 at 6:40 PM | Permalink

RE 487. very nice nasif. Someday on unthreaded we should pass the time of day and chat.

Posted Nov 18, 2007 at 6:43 PM | Permalink

#478 RomanM:

How did you get Loehle data post 1980?

Posted Nov 18, 2007 at 6:45 PM | Permalink

Oops, I got it, sorry

487. Gunnar
Posted Nov 18, 2007 at 6:53 PM | Permalink

#299 – #315, Steve Huntwork, I really appreciate your perspective and common sense. They may qualify as GQs. I think you correctly focus on the fact that while time averaged values may sometimes be useful, they are not fundamental parameters of reality. Understanding this, the answer to comments #397 and #426 becomes clear

#397 >> A few even postulate an imminent tipping point
#426 >> The MWP is important for another reason. If it can be established that the earth was considerably warmer in the recent past (i.e. within recorded history), it knocks the legs out from under Hansens tipping point conjecture

Except that the “tipping point” is falsified every summer

#436, Larry, no reason to be dismissive. What Jae says in #434 is quite cautious and correct.

#440, Douglas, this is a great point. As I’ve said many times, “peer review” is merely a QA mechanism for magazines. It is not a substitute for the scientific method.

488. Larry
Posted Nov 18, 2007 at 7:06 PM | Permalink

Gunnar, let me completely clear about something. I hold out the possibility that feedback could be high, low, negligible, or even negative. But its simpleminded to just outright declare that it doesn’t exist. Same for the greenhouse effect. The net effect may turn out to be negligible when all is known, but that’s not the same thing as it not existing. Anyone who claims that something that basic is a myth just adds a lot of noise to the discussion. The net effect may turn out to be negligible, but these are not myths.

489. jae
Posted Nov 18, 2007 at 7:40 PM | Permalink

474:

Truth be told. Dr. Curry is giving good pragmatic advice. Its not about the science. Its not
about the truth value of the proposition.

And that is correct, IMHO. I had a boss once who kept telling me that “perception is reality.” I challenged him, noting that his view is a political view, not a scientific view. Reality is often completely reverse to perception. This whole discussion of which journal is “best” is a manifestation of that same political view. Judith is right from a pragmatic approach, but wrong from a scientific approach. The truth shows up in the strangest places. Read Einsten, by Walter Isaacson.

490. John F. Pittman
Posted Nov 18, 2007 at 7:41 PM | Permalink

Dr. Loehle, not necessary now. RomanM #478 has done it for me. His approach rids us (or at least my concerns) of the teleconnection issue, as well as provides what I wanted to see. For the series part, his correlation and error estimates provide similar information. The only thing left is to take the plot and splice it on to yours. The colors are nice as well, as long as you change yours to green (lol). I note that his ~1940 is ~0.0 as is yours. Perhaps your graph, the spliced graph, and RomanM’s graph as an insert would be illuminating.

RomanM what a clever way to defuse the teleconnection issue.

491. jae
Posted Nov 18, 2007 at 7:48 PM | Permalink

In fact, a lot of TRUTH is showing up in this blog. I hope the scientists are watching.

492. Kenneth Fritsch
Posted Nov 18, 2007 at 7:52 PM | Permalink

Re #461

Peer review is no panacea, and no guarantee of anything. Peer review supervised by an editorial board without strong scientific reputations and an overt political agenda (as reflected by public statements by the editors) means little more than that the paper passed some sort of litmus test. Peer review supervised by an editorial board with strong scientific reputations and no overt agenda (as reflected by their public statements or lack thereof) guarantees nothing more than that the paper is original, moves the science forward, and is free of obvious methodological errors.

The first sentence in the paragraph above would appear to me to limit the remainder of the observations to minor differences in what may or may not be applied by the less knowledgeable and/or tenaciously analytical reader, as a very much less than full proof guide, based on a trust in the review editors definitions of what is original, moves science forward and is free of obvious methodological errors. That trust will evidently depend on how the reader views the motivations of the editors.

My observation would be that peer review is no guarantee of anything — period. It can be applied, with guidelines that are not uniformly or consistently applied, to limit the number of publications to those that that specific scientific community has explicitly or implicitly agreed have value. The quality and utility of peer review, in my view, varies widely from one scientific community to another and makes generalizations about it rather meaningless. Judgments of peer reviewed papers are ultimately in the hands of the interested reader with peer review practically used to avoid having to sort through too much junk to get to the valid papers and the rare gems.

493. Susann
Posted Nov 18, 2007 at 8:07 PM | Permalink

Peer review is only as good as the peers. 🙂

494. Posted Nov 18, 2007 at 8:20 PM | Permalink

# 488,

Thanks, Steven. It would be great! 🙂 It could be on Friday or Saturday, although I have some other activities non related with biocab.

# 492

Larry,

You’re right; however, we have to admit that the term “greenhouse” is not semantically adecuate to describe scientifically the process given in the atmosphere.

# 479

Craig,

And expect more coincidences with your plots. That’s precisely what the theory of truth on correspondence says, a theory must be consistent with other theories with which such theory is related. It refers to the descriptions of real phenomena. A description of an observed phenomenon should always be coherent with other descriptions of the observed phenomenon.

Seventeen or eighteen studies from about ten proxies reveals that something odd occured with climate through the MP. One study based on one proxy reveals that nothing occurred… mmmh… 😉

495. Craig Loehle
Posted Nov 18, 2007 at 8:23 PM | Permalink

By the way, my process for picking proxies was to search the archives, read the methods, and then download the data without seeing what it plotted out to look like. I know that is hard to believe, but true.

496. jae
Posted Nov 18, 2007 at 8:25 PM | Permalink

One of the problematical primary “outcomes” of the “elite journal” syndrome is that, once an article in one of these journals is published, there is a tendency for the “elite” scientists to reference it without reservation (“after all, it must be accurate, since it was published in this respected publication”). Thus, we have a situation where certain publications (such as Held and Soden for the negative feedback idea), are referenced to almost “prove” some concept, when it may not be true. We tend to build this upside down pyramid, which is as good as the bottom stone. Same with Ahrennius, who was NOT accepted as the Mesiah by his contemporaries.

497. Kenneth Fritsch
Posted Nov 18, 2007 at 8:26 PM | Permalink

Re: #478

If I eyeball a straight line trend through the instrumental versions of global, NH and the Loehle’ reconstruction sites, I see a significantly steeper slope for Loehle’s reconstruction sites than the global or NH series. They may correlate rather well, but I judge the trends over the time period in question differ signifcantly. It could be old eyes, but I think a calculated trend line for all three series would be appropriate.

498. Posted Nov 18, 2007 at 8:30 PM | Permalink

# 499

Craig Loehle,

I know it’s true. Have you considered the coincidences when collating ISI on your graphs? I didn’t either think on the final coincidence… but they matched effortlessly. 🙂

499. bender
Posted Nov 18, 2007 at 8:34 PM | Permalink

The precise method of proxy selection is very important in these kinds of studies. There are so many little ways for bias to creep into the analysis. That was the lesson that Burger & Cubasch tried to teach us: so many flavors of recon possible. What did they test, 2^8 flavors? 2^8 ways for bias to enter into the analysis! And that’s not even varying the source data.

500. Kenneth Fritsch
Posted Nov 18, 2007 at 8:47 PM | Permalink

Re: #497

Peer review is only as good as the peers.

That would be the short version of my relatively lengthy post. Maybe I would have said: A particular area of peer review is only as good as that particular community of peers.

501. jae
Posted Nov 18, 2007 at 9:11 PM | Permalink

500: Sheesh, in 500 I said:

(such as Held and Soden for the negative feedback idea)

Of course, I meant POSITIVE feedback.

502. bender
Posted Nov 18, 2007 at 9:13 PM | Permalink

Maybe you’ve been getting them mixed up all along? That would explain things. 😉

503. Gunnar
Posted Nov 18, 2007 at 9:13 PM | Permalink

#492, you’re getting all excited. Don’t see how you’re getting all that from #434.

504. jae
Posted Nov 18, 2007 at 9:17 PM | Permalink

Brilliant, bender. To use your vernacular, prove it.

505. steven mosher
Posted Nov 18, 2007 at 9:23 PM | Permalink

Gunnar. I’m sorry the GQ thing was mean.

506. steven mosher
Posted Nov 18, 2007 at 9:32 PM | Permalink

RE 499. Dr. Loehle I hope you enjoyed this as much as we have.

507. Posted Nov 18, 2007 at 9:54 PM | Permalink

#478

Great post RomanM,

The higher variability in the graph for the earlier years has a lot to do with the fact that fewer records were available for the averaging process.

Do you know the Climate Scientist answer to this problem? It is not stochastic modeling of the signal, it is variance matching.

Unless one believes that through teleconnection, a proxy can actually do better than thermometers, this type of approach provides a way to estimate a lower bound on the variability of any proxy using a given set of sites. The root mean square errors of the estimated global and NH temperature anomalies were about .34 C and .31 C respectively. It seems reasonable that any reconstruction using these sites would have a standard error (probably much) larger than that because of the increased uncertainty in estimating the local temperature.

Next step is to calibrate these thermometer readings to global record, using CVM or Mann’s method (CCE+variance match). Effect of scaling errors (we know that true scale is one) would be interesting to see, larger or smaller rmse?

508. Pat Keating
Posted Nov 18, 2007 at 10:26 PM | Permalink

512 Jaye

Amen. However, duplication and prediction checking take longer…….

509. Posted Nov 18, 2007 at 10:40 PM | Permalink

I have a paper in Energy & Environment, apparently in the same issue as Craigs paper. (See comments #282 and 286). E&E has a section that contains refereed papers and a section that doesnt. Knowing this, I asked that my particular paper indeed be refereed, and like Keenan, I would characterize the reviews as regular-to-thorough.

Also, publishing in high impact academic journals doesnt necessarily translate into high impact in the real world. M&M 2003, published in E&E, probably has had greater impact that many a paper published in GRL or even Nature, and without that there may never have been an MM 2004, nor a special panel of the NAS to look into the hockey stick, and so forth. And without E&E, we may not be observing this discussion and dissection of Craig’s paper today. In fact, these examples alone, confirm for me that science needs contrarian outlets for its own sake.

510. mccall
Posted Nov 18, 2007 at 10:56 PM | Permalink

re: 144 — I understand your position, but AR4 chose to go the other way. Mann-Jones’03 (and to a lesser extent Jones-Mann’04) dominate the push of AR4 1300 years-BP focus on lengthening the HS handle, instead of explaining the divergence problem.

Generous portions of precooked/canned spaghetti made this easier for AR4 SPM writers: en.wikipedia.org/wiki/Image:2000_Year_Temperature_Comparison.png

511. bender
Posted Nov 19, 2007 at 12:00 AM | Permalink

There is a serious problem with JEG’s insistence that Loehle’s proxies be weighted by their calibration statistics. It’s an idea that makes sense in theory, but is misleading in practice. It all has to do with the representativeness of the response during the instrumental period. I’ll get to this tomorrow if I can. [Of course, with those clues, maybe [JEG] can anticipate what I will say, and pre-empt me?]

512. Steve McIntyre
Posted Nov 19, 2007 at 12:40 AM | Permalink

There is a serious problem with JEGs insistence that Loehles proxies be weighted by their calibration statistics.

This is no more than Partial Least Squares regression (about which I’ve posted in the past). Mannian inverse regression is equivalent to this underneath the obscure linear algebra as shown in the past. It’s a multivariate method but there are many multivariate methods. This method lends itself to calibration overfitting in high noise situations as I’ve particularly discussed in connection with Ammann.

513. Al
Posted Nov 19, 2007 at 1:03 AM | Permalink

From a thought experiment perspective, I think there’s value in re-adding most of the tree-rings back and seeing what happens.

Essentially, take Mann98’s proxies and actually follow the repeated recommendation of removing all the strip-bark, bristlecones, foxtails, and any other species known to be particularly bad proxies. Also exclude anything that relies upon them.

Then treat the resulting melange in a statistically sane fashion, instead of by running the data through the PCA hockeystick-finder.

That is, aiming for: “A 2,000-Year Global Temperature Reconstruction Based on Available Non-Bristlecone Proxies”

The word “Available” puts pressure on whatever remaining restricted proxies are left.

514. John A
Posted Nov 19, 2007 at 6:54 AM | Permalink

Jules shows that fence-sitting can be extremely uncomfortable:

I am a regular reader of RealClimate.org which gathers distinguished scientists of the likes of David Archer, Stefan Rahmstorf, Ray Pierrehumbert, Gavin Schmidt and Michael Mann. These people are personally ersponsible for some of the msot exciting work in climatology, their blog has won a few awards and it is increasingly taken as authority by a number of newspapers, including my own “Le Monde” from Frogland. Blog posts on RealClimate are often entertaining, always informative, but it arguably leaves little room for heterodox climate views and it sometimes leaves the strange aftertaste that its authors are defending and selling their own research, while not explicitly acknowledging this partisanship. In particular, Michael Mann is the lead author behind the illustrious Hockey Stick graph, which is by any means a *very* controversial piece of research, and RealClimate.org (RC) has proven somewhat closed to discussion on the topic. Though i have not personally experienced censorship on RC, i have heard many accounts thereof. It is perfectly sensible to block global-warming-denialist trolls from spewing out insults on the forum, but not if they politely ask inconvenient questions.

Obviously, the difference between “global-warming-denialist trolls from spewing out insults” and “global-warming-denialist trolls … politely ask[ing] inconvenient questions” is a difference entirely in the eye of the beholder. Since Mann, Schmidt and Connelley delete the latter while claiming them to be the former, the result is the same, isn’t it Jules?

515. rhodeymark
Posted Nov 19, 2007 at 7:57 AM | Permalink

The main problem is that until recently, the Opposition was mostly represented by the despicable breed of “climate obscurantists” who have been polluting the blogosphere with a pure disinformation campaign, motivating their disparaging comments on all states of climate science by their own unwillingness to change anything about their fossil-fueled existence. These comments are always easily debunkable because they are not based on any scientific knowledge or reasoning. I would hate to be guilty of referring you to such pieces of junk, but if you want a taste , Texas Rainmaker, America’s Future or the editorials of the Wall Street Journal are quite good examples – there are unfortunately many, many more.

Take a second to digest that paragraph. The main problem seems to be that it is no longer a slam dunk to sneer, hand wave and appeal to authority. Jules is ignorant about the “opposition” as well. I have taken numerous energy conservation steps – even choosing a white roof replacement after reading Anthony Watts – but so sorry, a socialist eco-poverty just doesn’t ring my bell. If he is honest, he’ll take a good look around at his “not for me, but for thee” associates. Finally, folks here may well disagree, but I think the WSJ editorial page is a valid outlet to get unfiltered access to the public ear. The Frogland Gazette and other MSM outlets are much too compliant to the alarmists, imo.

516. Craig Loehle
Posted Nov 19, 2007 at 8:07 AM | Permalink

Mosher asked if I’m having fun. yes, very much, althouh not so fun to be insulted and implied that I cheated. I have so many ideas now for a second ms. What I really need is collaborators who can help evaluate the proxies. People with geological training. I can handle the stats and smoothing and writing. Anyone like that please contact me for round 2.
By the way, I have submitted 2 follow-up papers on divergence and temperature trends. I will keep you posted.

517. kim
Posted Nov 19, 2007 at 8:20 AM | Permalink

Rather more insinuated than implied, and suggestive of a guilty conscience, or at least revelatory of the insinuator’s view of science.
========================================

518. Hans Erren
Posted Nov 19, 2007 at 8:27 AM | Permalink

Craig,
Have you prepared a Supplemental Information package?
Raw proxies, processed proxies, method, weighting factors, results
Detailed meta-information about the used proxies (time span, number of entries, location, authors, url)

519. Steve McIntyre
Posted Nov 19, 2007 at 8:41 AM | Permalink

#520. Craig has emailed me to say that the proxy info should be ready today or tomorrow. It’s too bad that this wasn’t in place at the time of publication as he should have realized that expectations for non-Team players are higher.

520. John A
Posted Nov 19, 2007 at 9:03 AM | Permalink

I think the problem here is intrinsic to the multiproxy paradigm and not simply to Mannian-type statistical manipulations.
If there was such a thing as a global mean temperature, and if each proxy had a linear response to it, then it would be reasonable to be able to construct such a model using linear transformations and Fourier analysis.
But those are big “ifs”. The problem is that there is no such thing as a global mean temperature, and no reason to expect that different proxy sets in different locations with different local microclimates can be meaningfully synthesized without problems with spurious regressions, white noise, microclimatic influences overwhelming the “global signal”.
This is the fundamental problem of climate science and Loehle’s model is no better than the others because the assumptions underlying the multiproxy approach appear to be invalid.
I would also add that Loehle’s data has not been tested for autocorrelation, the assumptions of stationarity, linear response, normality and IID behavior being given as so axiomatic as to be unnecessary even to state them.

521. RomanM
Posted Nov 19, 2007 at 9:19 AM | Permalink

#510

Thanks,UC.

Next step is to calibrate these thermometer readings to global record, using CVM or Manns method (CCE+variance match). Effect of scaling errors (we know that true scale is one) would be interesting to see, larger or smaller rmse?

My main intent in this exercise was to see what would happen if Craigs methods were applied to the recorded temperatures rather than the proxies. A second thing was to get some idea of the variation in the result due to the choice of site. I agree that it would be interesting to do the calibrations you suggest along with some others, but the data for some of the stations I selected on the basis of distance was so sparse that it would have been necessary to exclude those sites so that the calculations would be done. One solution would be to look for some other stations in those cases on the basis that the temperature record was sufficiently long to be able to carry out the procedures. This could of course introduce other biases because longer histories might tend to go along with more densely populated areas.

#493: I didn’t choose those colours – R did! I think they are probably from an Xmas theme. 😀

522. steven mosher
Posted Nov 19, 2007 at 11:52 AM | Permalink

RE 520. Dr. L, you kept your cool and gave good answers unlike the laconic one who’s name shall
not be mentioned but with whom Willis is well aquainted.

and now a musical interlude

523. Craig Loehle
Posted Nov 19, 2007 at 1:20 PM | Permalink

Hans: I now have the proxy data (temperatures supplied by the sites/authors) ready, and the links to raw data except 2 I am waiting for reply from authors. I can supply these to anyone who wants them. They will be posted shortly online.

524. Carrick
Posted Nov 19, 2007 at 1:21 PM | Permalink

If there was such a thing as a global mean temperature, and if each proxy had a linear response to it, then it would be reasonable to be able to construct such a model using linear transformations and Fourier analysis.

But that’s the real problem. The system isn’t even linear in its time dependence on the forcing terms, and neither are the proxies being used. I would even go as far to say that the nonlinearities associated with the various feedback loops are poorly understood at best, and beyond the scope of what a current global climate model is capable of.

So you can’t even construct a reliable nonlinear model that you could use to perform the inversion from the relevant proxies. GIven the absence of a well understood physical model, I’m frankly concerned that any real policy weight is being given to these temperature reconstructions, especially when the temperature differences in global mean temperature between e.g. the Mann Hockey Stick and Loehle’s reconstruction are so small.

These differences may lie well within the systematic uncertainties associated with the differences between a linear system, and a nonlinear system with positive-feedback forcing terms, like this one.

525. Craig Loehle
Posted Nov 19, 2007 at 1:23 PM | Permalink

People wanted to see an overlay of all the proxies. If you do simple interpolation so they are all connected plots, this is what you get:

526. John A
Posted Nov 19, 2007 at 1:26 PM | Permalink

I think you’ve missed the rest of the URL there, Craig