A few days ago, Jeff Id drew attention to a recent study profiled in sciencedaily which stated:
Sea Ice At Lowest Level In 800 Years Near Greenland
ScienceDaily (July 2, 2009) — New research, which reconstructs the extent of ice in the sea between Greenland and Svalbard from the 13th century to the present indicates that there has never been so little sea ice as there is now.
The new study, Macias Fauria et al (Clim Dyn 2009), was coauthored by John Moore and Aslak Grinsted, whom we’ve encountered recently in connection with Rahmstorf smoothing, and Mauri Timonen, with whom we had very cordial correspondence in connection with our profiling of the long Finnish tree ring chronology.
Co-author John Moore had said in commentary here:
I strongly believe in making data available and codes available when the results are published – sometimes we work on data that others control who may not, unfortunately, want it distributed.
I wrote to lead author Macias Fauria requesting the proxy and reconstruction data for Macias Fauria et al 2009 – the sea ice reconstruction used two proxy series, an RCS version of the Finnish tree ring chronology and Svalbard ice core data. Macias Fauria replied that he could not provide the latter data as co-author Isaksson refused to make it public. He did provide me with the tree ring version that they used, the target sea ice series and the reconstruction. Obviously with half the proxy data missing, any statistical analysis of their methodology is thwarted.
The Macias chronology was not the same as the chronologies that Timonen had previously provided to me – Macias used RCS chronology, Timonen didn’t. This was quickly clarified in correspondence with Timonen and Macias Fauria. I did an RCS chronology calculation (using my RCS algorithm – to my knowledge, Briffa and cohorts have maintained secrecy on their code) on the ADV7638 measurement data that Phil Trans B required Briffa to archive last year (after prolonged obstruction by Briffa.)
I got a series that is recognizably related to the Macias chronology, but also critically different.
First, the Macias version has a somewhat different texture. It looks like it’s been somewhat smoothed – perhaps using Rahmstorf smoothing, perhaps not. (Note: A reader notes below that the text says that the smoothing is a 5-year cubic spline.) Secondly, the Macias version has a pronounced trend relative to my emulation from first principles from the 19th through the 20th century. Third, my emulation showed the frequently seen “divergence” between ring widths and temperature, while the Macias verion did not. Macias Fauria explained to Timonen that he modified the Advance10K data set by:
1. Not include the snags.
2. Remove series belonging to the last period in order to have a more evenly distributed sample depth along all the reconstructed period (no age selection was performed), as seen in Fig. 2 of the paper (otherwise most of the data was from the last two centuries).
Perhaps these changes to the data set account for the difference, perhaps it’s a difference in methodology.
Figure 1. Scaled Finnish tree ring chronologies. Top – emulated from Finnish ADV7638 archived by Briffa; middle – Macias version; bottom – difference.
Reconciling the difference is impossible right now because the data is incomplete and the originating code is thus far unavailable. I, on the other hand, for a mere blog post have placed the code that generates this graphic in the first comment and it should be turnkey with data and functions that I’ve placed online. Wouldn’t it be nice if the author Moore
strongly believed in making data available and codes available when the results are published.
While the ice core data is not archived, it is represented in small squiggles in dead-tree literature, which give some indication of the shape. It was discussed here where the following image showing very elevated values of the washout proxy discussed in Grinsted et al (JGR 2006) were shown:
These seemingly high 12th century values do not enter into the sea ice reconstruction of Macias Fauria et al 2009, because it begins in 1200. I’m sure that there is an excellent reason for not including 12th century data.
Climate Audit 
50 Comments
##LOAD INFO FILES
source(“http://data.climateaudit.info/scripts/briffa/collation.briffa_2008.txt”)
# briffa – RW; # tf -CRN; # briffa.info
sum(tempf) #430
############
#emulate RCS
temp=!is.na( match(briffa$id,briffa.info$id[tempf]) ) ; sum(temp) #76800
tree=briffa[temp,1:4];names(tree)[4]=”x”
tree$x=tree$x/10
#make Finnish subset of Briffa rwl
#negative exponential fit
source(“http://data.climateaudit.info/scripts/treeconfig.functions.txt”)
chron=RCS.chronology(tree,method=”nls”)
chron$coefficients
# A B C
#35.22253589 82.61107011 0.01370280
#huger fit
fm.nls <- nls(x ~ A*age^B*exp(-C*age)+D,data = tree,
start = list( D=mean(tree$x,na.rm=T)/4,A = mean(tree$x,na.rm=T), B=.7,C= .01 ),
alg = "default", trace = TRUE,control=nls.control(maxiter=50, tol=.001, minFactor=1e-4));
coef(fm.nls)
# D A B C
#36.59115357 77.25858428 0.02959149 0.01526415
B<-coef(fm.nls);
huger=function(x) (B["A"]*x^B["B"]*exp(-B["C"]*x)+B["D"])
#a= 1:max(tree$age); age0=tapply(tree$x,tree$age,mean)
#plot(a,age0,type="l",xlab="Age",ylab="RW"); lines(a,huger(a),col=2)
#this shows exp decline
tree$fitted=huger(tree$age)
tree$resid=tree$x-tree$fitted
chron.huger=ts (tapply(tree$resid,tree$year,mean,na.rm=T),start=min(tree$year) )
#not much difference between Huger and neg exp
##COMPARE TO MACIAS
#load macias from email
macias=read.table("http://data.climateaudit.info/data/timonen/maciasrw.dat",header=TRUE)
names(macias)
compare=ts.union(emulation=window(chron.huger,start=1200),macias=ts(macias[,"RW"],start=macias$year[1]) )
compare=ts( scale(compare),start=tsp(compare)[1])
compare=ts.union(emulation=compare[,1],macias=compare[,2],delta=compare[,2]-compare[,1])
# GDD(file="d:/climate/images/2009/proxy/RCS_macias_vs_emulation.gif",type="gif",w=600,h=600)
par(mar=c(3,4,2,1))
plot.ts(compare,main="RCS Chronologies")
# dev.off()
Re: Steve McIntyre (#1),
R code confirmed completely “turn key”.
Re: Jeff Alberts (#21),
The problem is, why stop there when there’s an opportunity to compare 11th Century Greenland with today? Is there something they didn’t want to talk about?
The narrow focus is upon the data: why the difference between the recovered chronology and the reconstructed one by Steve?
And why do I keep seeing Hockey Sticks?
Re: John A (#23),
Yeah. I meant what’s the problem with today’s sea ice levels if it’s been that way before. Obviously the world didn’t come to an end.
Re: John A (#23), Everywhere psychoanalyists look, they see phallic symbols, but for climate scientists (and Canadians) it is hockey sticks. Simple explanation, like rorschach tests…
Re: Craig Loehle (#32),
You mean you see a HS in that plot. Imagine that. And all this time, I was looking for a squash racquet.
snip – irrelevant
Maybe it’s just me, but I’m not buying either smoothing or removal of late-period series as the sole reasons for the difference. I find it difficult to imagine a filter that would give one response at one endpoint (1200) and a completely different response at another endpoint (2000) . . . and sometimes enhance but sometimes diminish peaks of approximately equal amplitudes.
Me smell data mining.
Re: Ryan O (#3),
One wonders if the following decisions might have resulted in the difference:
It will be nice to see Macias’ results before and after the data removals. It might be data, but it also might be something in the algorithm.
Maybe he’s done some Rahmstorf smoothing on the endpoints. As JEff Id will recall, Mannian end point handling (that Nick Stokes is so enamored with) had a very strange impact in Mann 2008. Because of the “Divergence” problem for MXD (Density) proxies after 1960, Mann deleted this downward trending data and substituted infilled data. A great way to start Mannian smoothing.
Re: Steve McIntyre (#4), Unfortunately, my familiarity with the divergence problem is about zero. However, I will say that if the divergence problem leads one to throw away series that don’t show a certain correlation with temperature . . . well, the Macias result is almost Q.E.D. No filters required.
.
I really need to read Mann 08 in detail. I’m pretty familiar with MBH, but I know next to nothing about Mann 08.
Re: Ryan O (#6),
The Divergence Problem is well worth reading about. I’ve got a number of threads about it with quotes that need to be read to be believed.
Basically, the problem is that tree rings go down in the last half of the 20th century while temperatures go up – rendering the proxies problematic, to say the least. Climate scientists “deal” with this by calling it the “Divergence Problem”. They assume that the Divergence Problem is due to some unknown anthropogenic cause and, relying on this cargo cult practice, assume that it doesn’t matter and delete the inconvenient data – sometimes, as in IPCC TAR, without any disclosure.
This practice did not originate in Mann 2008; Briffa originated it. It’s a disgraceful practice.
Re: Steve McIntyre (#7), Ah. So in a complex multivariate calibration problem, the correct way to proceed is to:
.
1. Hypothesize a relationship.
2. Remove all points that do not follow said relationship.
3. Replace removed points with made-up ones that follow said relationship.
4. Extrapolate.
5. Publish.
.
Awesomeness.
Re: Steve McIntyre (#7),
Couldn’t agree more. I find it one of the most disturbing aspects of the way evidence is presented in respect of AGW. What harm is there in a simple change from a solid to dashed line to highlight the divergent period? Invite further investigation if it is an issue.
Carig Loehle has an interesting perspective with the plausible suggestion that growth might peak at some optimum conditions, and if so, this would indicate a systematic under-estimation of past temperature. This is at least as appealing as other possible suggestions.
The 2008 study by D’Arrigo et al (“On the ‘Divergence Problem’ in Northern Forests: A review of the tree-ring evidence and possible causes”) is well worth reading. It says:
How unlucky is that – losing temperature sensitivity just at the crucial moment. Ouch!
Well this might just be the proof needed to confirm the long held belief that Viking’s did indeed have Class 5 Icebreaker Longboats.
It appears that Aslak Grinsted et al had already concluded back in
20052006 that the 12th century was substantially warmer than the 13th.As quoted by World Climate Report (12/6/08),
Recall that the warmest part of the MWP was the 10th century, when Greenland was settled and at the very end of which Vinland was discovered. See Loehle and McCulloch reconstruction.
The Greenland colony was still flourishing in the 13th century, but froze out during the 14th, and was gone by the 15th. C. 1427 maps by Claudius Clavus show Greenland connected by solid ice to northern Europe. (See http://www.museumofmissinghistory.org/items/details.php?id=122, etc. Clavus’s second map has some dubious Greenland place names on it, but his maps still undoubtedly contain substantial real data. Later maps followed Clavus in linking Greenland to Europe.)
So despite the MWP, I have no problem with the possibility that Svalbard may have been icebound as early as the 13th century.
I’ll never understand why any “scientist” would accept this practice of withholding any data used in published work. I don’t understand how such reports get published. And I don’t understand how they could be of any use in subsequent research. “Cargo cult” — that’s great.
Subtract the McIntyre reconstruction from the Macias and what pops out?…..A hockey stick.
I found another, somewhat more informative graph of what I believe to be the O2 data for the ice core through the web site for another paper by Isaksson et a different set of al.
Figure 4 actually shows the points along with a bunch of different smooths. The points have extremely high variability and are all over the place.
Steve M.,
Maybe you can obtain the data of the Svalbard ice core from the department of Prof. Oerlemans of Utrecht University, they are named in the Svalbard research project of Elisabeth Isaksson of the Norwegian Polar Institute:
http://thule.oulu.fi/narp/Projects/a_natural/Isaksson.htm
They published part of the findings in 2002.
Here we go again. If the authors don’t release their data and methods, can’t we simply say that until they do, it is not a scientific study?
Sciencedaily – Not with this nonsense
ChickenBoneThrowingDaily – Yes
Ferdinand Engelbeen; Nice link.
The bottom of the Lomonosovfonna ice core examined glacier was dated to approx 1200 AD.
That may tell you be that there was no glacier there around 1200 AD at peak of MWP.
“Least ice in 800 years” means that we are FINALLY out of the Little Ice Age…..
I can accept that you can derive a temperature series from the Tree-ring chronology with large errors and the Ice core data provides useful information about Lomonosovfonna but says little about conditons south of there. Combining tree ring data from northern Scandanvia and just one bore hole to determine Ice extent over much of the North Atlantic seems to be drawing the bow well past breaking point.
Re: MarcH (#17),
I have to agree with Marc on this.
Some useful papers.
Accounts from 19th-century Canadian Arctic Explorers’ Logs Reflect Present Climate Conditions
(Eos, Transactions American Geophysical Union, Volume 84, Issue 40, p. 410-412, 2003)
– James E. Overland, Kevin Wood
Historical variability of sea ice edge position in the Nordic Seas
(Journal of Geophysical Research, Volume 111, Issue C1, January 5, 2006)
– Dmitry V. Divine, Chad Dick
I do not now if anyone here has looked at this…
Historical Ice Chart Archive (1553-2002) (ACSYS)
snip – please don’t make general complaining editorials.
Which would mean more than 800 years ago there was less sea ice. What’s the problem?
I purchased a book at one of the Yellowstone National Park bookstores on vacation this year: “Recent and Ongoing Geology of Grand Teton & Yellowstone national Parks” by John M. Good and Kenneth L. Price. [Grand Teton Natural History Association, Moose, Wyoming, 1996. ISBN 0-931895-45-6]. On page 49, the authors describe “If you climb to the few glaciers in the Tetons, you will find Little Ice Age moraines, a few hundred feet or a few hundred yards downvalley from modern glacier snouts.” They also report that “The Teton Glacier has been retreating ever since [re: 1850], slowly since the 1930s, much more rapidly since.” Earlier in the chapter they describe how Yellowstone Lake may have had as much as 4,000 feet of ice over it during the last major ice age. Certainly as the climate began cooling beginning in the 13th century, ice increased in the Arctic. Now that the climate is warming again,retreating ice should be expected. Using 1200 as the starting point may have been necessary due to poor data quality from the earlier period but that caveat should always follow any pronouncements from the report. Curious that the oft-cited data plots for rising air temperature during our the modern era also start at 1850.
What does tree ring data has to do with ice extent? What theory or physics tie them together?
So, 800 years ago it was warmer in the Arctic and therefore temperatures are not unprecedented in 1000 years
great, isn’t that what the sceptics have being saying all this time?
Re: MangoChutney (#26),
Where do you get the idea that “800 years ago it was warmer in the Arctic”?
The conclusion of this paper is:
“The presently low maximum sea ice extent in the
Western Nordic Seas is unique over the last
800 years, and results from a sea ice decline started
in late-nineteenth century after the Little Ice Age.”
OMG it’s worse than we thought.
Phil,
Choose one:
Sea Ice is the lowest in 800 years because
1. Temperatures are higher
2. Temperatures are the same
3. Temperatures are lower
4. Because of random natural variations
5. For some unknowable reason.
You can either be sensible and choose 1 or ornery and pick 4 or 5. I don’t think you’d pick either 2 or 3. Of course we’re just looking at one small area, so it doesn’t mean much anyway.
Re: Dave Dardinger (#29),
I would say 1 (as far as the Arctic is concerned) with a contribution from 4.
Why do you think that is important?
Steve said: “First, the Macias version has a somewhat different texture. It looks like it’s been somewhat smoothed – perhaps using Rahmstorf smoothing, perhaps not.”
In the paper the smoothing is described as follows:
“As with the d18O time-series, the tree-ring chronology was smoothed with a 5-year
cubic spline smoothing function.”
Steve: thanks for noting this.
Phil
Surely if sea ice is unique in 800 years this means it is not unique in, say 1000 years? Something over 800 years ago must have caused the previous “uniqueness” 800. What would your explanation be for this uniqueness, given you agree with Dave the current “Sea Ice is the lowest in 800 years because Temperatures are higher”?
Re: MangoChutney (#33),
No that’s an absurd logical fallacy, the period of study is 800 years, uniqueness within that period says absolutely nothing about what happened before.
Re: Phil. (#34),
Quite so.
Equally please note that the Svalbard index in Grinsted et al 2006 and various related discussions by Grinsted, Moore note MWP in Svalbard – these discussions would be interesting to review at some time. These are not reviewed in Macias Fauria et al and leave an impression of opportunism in the selection of 800 years. I’d be interested in any information from the authors on this matter that would remove this impression.
Re: Steve McIntyre (#35),
I interpreted from reading the paper that the ice core went back to 1200 and that that defined the time period?
“In 1997, a 121-m ice core was retrieved from Lom-
onosovfonna, the highest ice field in Spitsbergen, Svalbard
(1,250 m.a.s.l.). The core was sampled for d18O with 5 cm
resolution (Isaksson et al. 2001), and dated using a com-
bination of known reference horizons and glacial model-
ling (Kekonen et al. 2005). The period covered by the ice
core is A.D. 1200–1997.”
Isaksson’s paper in 2003 shows analysis back to 1400AD.
Isaksson et al., Physics and Chemistry of the Earth, Parts A/B/C, Volume 28, Issues 28-32, 2003, Pages 1217-1228 Ice cores from Svalbard––useful archives of past climate and pollution history
Re: Phil. (#34),
Phil,
Accepted, my extrapolation was clearly not supported by the information provided
Hallo,
this paper might answer some questions about the MWP in Svalbard:
Virkkunen, K., J. C. Moore, E. Isaksson, V. Pohjola, P. Perämäki, T. Kekonen, (2007)
Warm summers and ion concentrations in snow: present day and Medieval Warm Period comparisons from snowpits and an ice core from Lomonosovfonna, Svalbard, Journal of Glaciology, 53 (183), 623-634
… The most obviously similar layers are in the bottom few metres of the ice core, most likely representing part of the MWE. In addition, the lower part of the oxygen isotope record shows values that are more positive than during the Little Ice Age, and are similar to those in the 20th century (personal communication from T. Martma, 2007). We conclude that, during that period, conditions for melting were similar to the summer of 2001.
Anton
Just contrasting this:
“This suggests that the Medieval Warm Period in Svalbard summer conditions were as warm (or warmer) as present-day, consistent with the Northern Hemisphere temperature reconstruction of Moberg et al. [2005].”
With:
“We see that the sea ice is shrinking to a level which has not been seen in more than 800 years”
Both from Aslak Grinsted. The second statement doesn’t overturn the first but not mentioning that tidbit certainly gives a different perspective because the presumed cause automatically shifts from nature to humankind. Who’s to blame for this bit of misinformation; the journalists, the press office or the scientists?
Does information like this many anyone else angry that the recent G8 summit achieved so little. They couldn’t even push for a no-brainer resolution like this one: http://bit.ly/e0c7K
Re: angry environmentalist (#41), Perhaps this should go to unthreaded as the host has asked?
A question,
We saw in 2007 that changing wind patterns dramatically affected the ice extent in the Arctic. Would these patterns therefore not have some effect on ice cores taken in the future?
If so, how can we quantify what effect changing wind patterns might have had in the past?
Re. Phil # 34.
I think what MangoChutney was alluding to was if the study was of a 800 year period because that was the total lenght of ice core available, meaning the ice glacier didn’t exist before 800 years ago. Then what he said was logically correct.
Phil, do you know if they reached the bottom of the glacier with the ice core. This has important implications.
Re: raytoster (#45),
IIRC, you can’t use the data from the bottom of a moving glacier. Plastic flow starts to scramble the layers at some point.
Re: raytoster (#45),
Here you are.
reality check again:
Why not go for it big style?
Warmest period in 100.000 year
Click to access 201.pdf
And
http://www.gfy.ku.dk/~www-glac/ngrip/presse_070804_eng.html
And Yes it was warmer than today before that.
“…at least a 5 K warmer temperature in the
Eemian than at present..”
Have not been found the dating of this remnants of plants.
Here is a similar story
Not so warm in 400 year may the report been named today but since this article is some year old is it still science involved.
“Entombed Plant Communities Released by a Retreating Glacier
at Central Ellesmere Island, Canada”
Click to access Arctic37-1-49.pdf
FROM THE ABSTRACT ” The release of a dead but well-preserved high Arctic plant community, entombed for about 400 radiocarbon years (WAT-778 and 789)
under glacial ice at Twin Glacier, central Ellesmere Island (78″53’N7,5 35%)’ is reported. Remarkably intact plants have been emerging from under
the ablating front of this polar glacier which has been retreating for several decades”
In short: the glaciar advanced in the beginning of little ace age and covered plants that now are found quite well preserved.
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