Climate Audit

bender

Your question as posed is not answerable. Is what a general phenomenon? Is what a fortuitous result?

In any interaction between methods and data, the effect of a method will often depend on the nature of the data. The amplification of a cycle in a series that has no cycle is a fairly common sort of effect, which is why I spotted it instantly when I first saw the Emanuel paper. It’s how I know to cite Slutzky (1937) and Yule (1926). It’ll happen with any white noise, but if there is red noise it will happen more readily.

Good enough?

bender

1. Hey, it’s a start. You’re to be commended.
2. There is no dataset with this property. Because if you design the smoothing filter just so you’ll get a cycle.

Your question is quite a large one that I can’t answer: Describe all combinations of (i) datasets and (ii) filters, and tell me which combinations will/will not cause a cycle where none exists in the unsmoothed data. Oy!

TCO

Oh…bla bla bla. They can replot the figures, and they need to clean the whole thing up and there are lots of good journals. Sheesh.

TCO

You can write the paper up without him having owndership. It will change as you get work done, may morph into more then one, etc. Plus even if you had posted the whole thing here, he would not own it. Plus, it would be inappropriate to put his name on the paper unless he had a real contribution, regardless of blog ownnership.

TCO

If he made a significant contribution, then he NEEDS to be included. But not because of some issue with the blog. If you posted this on drudge, would you give drude a co-authorship?

yw on lecture. Like my mom says, if you can’t be good be careful. and accidents cause people.

TCO

feels good on my fanny…

Pat Frank

TCO, it may shock you to know that journal editors (in my experience, anyway) don’t share your cavalier attitude about pre-publication. Differently plotted analyses or not, they may object. It’s not just copyright with respect to figures, it’s the analyses and the data themselves. Editors don’t want their journal upstaged by claims of earlier priority.

If that weren’t the case, I could just re-publish my first paper over and over again, with just a new graphical presentations. Of course, some people actually do that. 🙂

Here’s another aphorism to put alongside TCO’s, bender: Err on the side of caution. (please)

bender

Re #1
A second reply to your question, TCO. Not sure if you know how to read periodiograms, but look at the decadal peak at frequency ~ 0.1 in the graphs with the y-axis labelled “spectrum”. See how that peak is present in the unsmoothed data (moreso in SST than PDI)? That is what Emanuel’s multi-stage smoothing is doing – exaggerating that decadal peak by removing the higher frequency variability. See how the right portions of those curves drop down as you increase the smoothing? That;s why Emanuel’s curves “wiggle-match” pretty well. Except they’re decadal cycles, not high-frequency noisy wiggles.

To generalize: any dataset with a mid-range spectral peak like that can have that peak emphasized if you smooth repetitively. (assuming the filter has certain properties, which Emanuel’s does.)

Whether you think this is ok or not depends on what your interpretation is of that peak in the raw data. Is it noise? Is it a cycle? Is it interpretible as ENSO or NAO? If it has an interpretation in the raw data, then it has the same interpretation in the smoothed data.

Good?

TAC

#16 I am not sure I understand the implications. The correlations (as defined by R or R^2) of the smoothed time series are presumably “valid” — at least in the sense that they are computed correctly and are therefore reproducible. However, it would seem that, because of the complex time series structure, it would be difficult — maybe impossible — to attach a statistical significance to the correlations.

Considering the physical processes for a moment, the observed correlations would be consistent with either coincidental (random) low-frequency noise in both series, or a common causal factor with low-frequency structure, or one variable forcing the other (again with low-frequency variability). Given the short datasets, there isn’t much evidence to reject any of the alternative hypotheses.

Is that the main point here?

bender

Re #17
I think this actually does happen. A paper does have to be “novel” to be acceptable. Look at the review criteria for any major journal.

TAC

Re #21

One other thought: Because of the temporal correlation, the effective sample size for the smoothed series may be very small — possibly on the order of 5 or less (the effect of smoothing is to eliminate the high-frequency signal, which reduces the effective sample size if low-frequency noise is present [it is important to note that smoothing does not always lead to a loss of information — e.g. the mean of iid Gaussian (N[mu,1]) data contains all the information in the sample). If the smoothing is having this effect, then it is not at all surprising that one observes increasing R^2. In the limit as effective sample size approaches 2, fit becomes perfect and R^2 approaches unity.

bender

At this point it’s probably worth mentioning: Kerry Emanuel is obviously a smart guy. None of this will surprise him much. We’re not trying to refute his paper, because I don’t think that’s possible (unless his time-space frames were cherry-picked). What we”re doing is trying to get a robust estimate of the SST effect on PDI, as opposed to a fragile, exaggerated estimate. Did PDI increase by 100 ± 10% over the last few decades? Or did it increase by only 50 ± 20%. The final answer won’t overturn his hypothesis test. But it will probably downgrade his risk estimate.

This is not about attacking people. It’s about getting precise estimates of GW effects. And it’s about showing the tremendous value of an open, collaborative auditing function.

KevinUK

#5 and #25 Pat,

I disagree although copyright could well be used as an excuse by some editors for not publishing it will be exactly that i.e. an excuse from an editor who does not want to publish the paper anyway because it doesn’t fit in with their (political) agenda.

Please remember just what this is all about. There are people out there (many of them in control of the IPCC) who want us to change the way we live. They are attempting to come up with evidence for ‘signals’ that in their opinion prove that global warming is down to our (uncontrolled) use of fossil fuels. They are using this ‘proof’ to justify the introduction of controls on how much fossil fuels we consume. They are IMO deliberately taking advantage of the MSM propensity for alarmism and sensationalism to get their propaganda into the media and so engrain their opinions into the minds of the general public.

For the sake of what I hope everyone agrees are our cherished civil liberties, we must all stand up to this onslaught. It is clear that the MSM want the alarmism to continue as this increases either their viewing figures or sales of their newspapers so there is little chance that any refutations of these claimed signals will be heard. So without equal access to the MSM we are therefore left with limited ways of getting across an alternative message – the message that the science that underpins the claims for AGW is weak at best and arguably (as in the case of the HS) contrived. If blogs/forums are one of only a few means available by which this message can be put across then so be it. It staggers me just how much information I have been able to find out thanks to even just this blog let alone many others. Thanks to the internet those of us who choose to research the alarmist claims we are exposed to in the MSM can find out what lies behind the claims. Sadly in most cases there is little if any real science (particularly when it involves epidemiology).

KevinUK

TCO

Woooosh!

David Smith

The Mann/Emanuel paper (EOS, June 13, ’06) is an important paper, perhaps moreso than the Emanuel 2005 paper.

1. It uses a statistical argument to remove the AMO from the historical record, which leaves global warming, rather than a major natural cycle, as the cause of the increase in hurricanes since 1995. Sort of like purging the LIA and MWP from the record.

2. If it is true, it is a stunning development which enhances Mann’s credibility in tropical climatology and his credibility as a master statistician.

Mann’s statistical arguments are beyond me, so I have no way of judging the paper. As I’ve mentioned, though, their choice of a “decadal” smoothing technique for SST (different from that of the Emanuel 2005 paper), and the use of pre-1900 Atlantic storm count, trigger my “hmmm” alarm.

TCO

It’s kinda buried, so how about holding my hand and spelling it out exactly. Let’s start with, when you say “would not increase” do you mean, “would decrease”, “would stay exactly the same” or “would increase a very small amount”?

bender

Re #32
We are now at that point we always seem to get to, TCO, where you start trying to put words in my mouth, I choke, and the horrible force-feeding experiment goes on for days. I have learned to avoid that stage, as the audience does not enjoy it. The conversation on this topic now has amazingly diminishing returns for me. I mean exactly what I said. If you don’t understand it, you’ll need to get yourself an interpreter.

TCO

Why don’t you directly answer the questions instead of posting a frequency versus correlation graph.

bender

TCO, if you have two white noise series, and they correlate with each other, then how on earth is smoothing out that white noise, which is the basis for the correlation, going to increase the correlation? It will inevitably decrease it. Think! The other scenarios you will inevitably come up with will require a similar style of thinking.

You’re like Bart Simpson in Sunday school: “What if a guy is half man/half robot – does all of him still get to go to heaven?”

I’ve got to go. Don’t blame my absence today on a lack of willingness to entertain you.

David Smith

I was doing more hurricane reading on the internet this morning but hit this…Darn.

link

TAC

#41 Errata: “Cor” and “cor” both refer to the cross correlation between two time series; “backup operator” should be “backshift operator”.

Also, anyone interested in plots of the correlations can generate them with the following R commands:

alpha

Douglas Hoyt

Bloom,
That dust has been coming off of Africa for centuries and is not new. See, for example, MacDonald’s Atlas of the Oceans, published in 1938, that clearly shows the Saharan dust cloud. Samples of ocean sediment in the Caribbean also shows Saharan dust going back centuries and longer.

Steve McIntyre

Landsea picked up the fixed end point issue in his comment as follows:

My first concern is that Emanuel’s figures2 do not match their description: his Figs 1–3 aim to present smoothed power-dissipation index (PDI) time series with two passes of a 1-2-1 filter, but the end-points “¢’‚¬? which are crucial to his conclusions “¢’‚¬? instead retain data unaltered by the smoothing;

Emanuel’s reply was:

Landsea correctly points out that in applying a smoothing to the time series, I neglected to drop the end-points of the series, so that these end-points remain unsmoothed. This has the effect of exaggerating the recent upswing in Atlantic activity. However, by chance it had little effect on the western Pacific time series, which entails about three times as many events. As it happens, including the 2004 and 2005 Atlantic storms and correctly dropping the end-points restores much of the recent upswing evident in my original Fig. 1 and leaves the western Pacific series, correctly truncated to 2003, virtually unchanged. Moreover, this error has comparatively little effect on the high correlation between PDI and SST that I reported1.

Gerald Machnee

Re #43 – This year’s excuse is the dust. Last year it was nothing but Global Warming. My understanding is that NASA is doing a study, but some insist on jumping to conclusions. Sounds like (A)Global Warming is a lot weaker than many thought.

Willis Eschenbach

Re 43, Steve Bloom, you say:

Re #24: bender, you seem to keep wanting to believe that Emanuel asserted something beyond a vague correlation between SST and PDI. He didn’t …

Quotes from the Emanuel study:

Here I define an index of the potential destructiveness of hurricanes based on the total dissipation of power, integrated over the lifetime of the cyclone, and show that this index has increased markedly since the mid-1970s.

… increased markedly …

I find that the record of net hurricane power dissipation is highly correlated with tropical sea surface temperature …

… not the “vague correlation” you claim, but “highly correlated” …

My results suggest that future warming may lead to an upward trend in tropical cyclone destructive potential, and”¢’‚¬?taking into account an increasing coastal population”¢’‚¬? a substantial increase in hurricane-related losses in the twenty-first century.

… upward trend in tropical cyclone destructive potential … substantial increase in losses …

There is an obvious strong relationship between the two time series (r^2 = 0.65), suggesting that tropical SST exerts a strong control on the power dissipation index.

… obvious strong relationship … strong control … (note that the real r^2 is only 0.23 or so)

But the large [PDI] upswing in the last decade is unprecedented, and probably reflects the effect of global warming.

… unprecedented …

Did you actually read the paper?

w.

Willis Eschenbach

Whoa, stop the presses! I just found an outrageous site that makes maps of any correlations you might think of, and then some.

Here’s a sample that’s relevant to the current discussion. It’s a plot of the Atlantic Multidecadal Oscillation vs SST, for August to October.

Note the red spot in the hurricane main development region …

Go try it, lots to learn.

w.

Gerald Machnee

Re #49 – Yes I have, but that is not the point. Last year at RC, it was nothing but AGW. This year it is excuses.

David Smith

Emanuel’s Figure 3 uses an annual average (instead of A-S-O), taken from 30S to 30N (instead of sticking to the Northern Hemisphere where the storms are located).

I’ll see if I can get the site mentioned by Willis in #52 to generate SST for a proper region (A-S-O, inside Emanuel’s combined boxes) versus the one he chose (annual average, over 30N to 30S). He chose that odd combo for a reason.

bender

Re #56
Yes it is possible to do what you are asking from that site. You just need to swtich pages, to a page devoted to time-series. I was going to post an example of this, but thought I might be accused of wasting bandwidth.

bender

Re #59

From Klotzbach’s conclusion:

These findings are contradictory to the conclusions drawn by Emanuel [2005] and Webster et al. [2005]. They do not support the argument that global TC frequency, intensity and longevity have undergone increases in recent years. Utilizing global “”best track” data, there has been no significant increasing trend in ACE and only a small increase (~10%) in Category 4–5 hurricanes over the past twenty years, despite an increase in the trend of warming sea surface temperatures during this time period.

1. The only problem with his line of argument is the old adage "absence of evidence is not evidence of absence". Given the contradictory results, someone is going to have to figure out the source of the difference. Is it ACE vs PDI? Smoothing vs. not smoothing? Pinning vs. not pinning? Framing? There are many possibilities. I would welcome Bloom’s analysis.

2. TCO won’t like this paper because there’s an "L" in GRL.

Willis Eschenbach

Well, here’s a fascinating plot from the site I mentioned above …

The interesting part is that the strongest correlation is not to the MDR in the Atlantic … it’s the temperature in the Pacific.

Go figure …

w.

Willis Eschenbach

Hmmm … maybe it didn’t like the pictures on after the other … here’s the other two again …

and

w.

Willis Eschenbach

Great … now all the pictures show up. Maybe Steve or John A. can clear up the confusion. In any case, the fascinating part to me is that, although there is some correlation between the Atlantic SST and the Atlantic hurricanes, the stronger correlation is with the Pacific SST. Here’s the full year …

Now, the amazing part of this to me, in addition to the correlation with the Pacific, is the correlation with the SST off of Spain … what’s up with that?

w.

David Smith

Willis, the correlated Pacific equatorial region you show is the famous El Nino / La Nina region

David Smith

Re #66

The region west of Spain is one that runs “cool” during the “many-big-hurricane” phase of the Atlantic multidecadal oscillation (that’s the phase we’ve be in since 1995)

I believe that classical meteorology says:

1. If the equatorial Pacific is warm, then El Nino is active and Atlantic hurricane activity is low.
2. If the equatorial Pacific is cool, then La Nina is active and Atlantic hurricane activity is high.
3. If the area off Spain is cool, then the AMO is in an active phase and Atlantic hurricane activity is high.

If you’ve established the above, you’ve demonstrated that your technique identifies two well-known weather correlations, and helps establish the existence of the AMO. Caution: demonstrating that the AMO truly exists will put you into direct conflict with Mike Mann.

bender

Re #71
Let’s try again.

Suppose your two series are x and y. Here are the commands in R to do a frequency coherence plot:

xy ASSIGN cbind(as.ts(x),as.ts(y)) # create the time-series vector pairing
xy.spc ASSIGN spectrum(xy,spans=c(3),plot=F) # generate the spectrum, smooth it, don’t plot it, store it in xy.spc
plot(xy.spc,plot.type=”coh”) # plot the coherence spectrum

ASSIGN = less-than sign followed by minus-sign, no space.

bender

Re #70
But David, the correlation between Atlantic PDI and Spain SST in #66 is dark orange = +0.55.

bender

There’s probably little chance Willis be able to follow my fragmented directions on how to generate a coherency spectrum. [If you can manage, Willis, I’m almost sure it would be worth the effort. Meanwhile I had better figure out this tex thing.]

bender

Ok. From now on I’ll use “ASSIGN” in text posts, but the actual operator in scripts. Apologies to the readership.

David Smith

Re #82

link

bender

David Smith,
Would you be willing to write a one-sentence/one-paragraph summary of the difference(s) between PDI (Emanuel’s ‘Power Dissipation Index’) and ACE (Klotzbach’s ‘Accumulated Cyclone Energy’)?

David Smith

RE #82

I’ll give it a try:

Accumulated Cyclone Energy (“ACE”) indicates the kinetic energy of a storm. It is the sum of (the maximum windspeed squared), as measured every six hours.

Power Dissipation Index (“PDI”) indicates the dissipated power of a storm. It is the sum of (the integral of the maximum windspeed cubed), as measured every six hours.

Basically, they do the same thing, but the PDI will rise faster than ACE as windspeed rises, because ACE uses squares while PDI uses the integral of a cube.

The general practice has been to use ACE. PDI was created by Emanuel, I believe.

Ken Fritsch

Willis, one final comment (bedtime): I think you’re doing something quite valuable with your new plotting tool. Your method may be able to provide useful clues about ocean and coupled circulation patterns. You may want to demo this for Judith.

Agreed. On the other hand, it could be a great tool for data snooping.

Steve McIntyre

#63. It’s interesting that the SST offshore Guyana to the south of the hurricane tracks should be so correlated with PDI (Guyana itself doesn’t get hurricanes because of the wind patterns , I guess.) Curiously these SSTs presumable correlate with Quelccaya ice core somehow – the precipitation comes from Atlantic monsoon rather than the Pacific and the connection to El Ninos would be indirect i.e. through relationship of the Atlantic monsoon to El Nino.

bender

Re #88
I had noticed that too, but didn’t want to comment for fear of putting my ignorance on display. Throwing caution to the wind: maybe Guyana ocean temperatures are part of a larger pattern of circulation (such as the whole TH circulation David Smith is pointing to)? Regardless, the time-series properties need to be looked at – in multiple areas. This IS interesting. (But surely the Emanuels of the world have already looked at this? On the other hand, maybe in their search for the GW ‘fingerprint’ they’re not seeing all the other fingerprints?)

David Smith

Re #87

The west Atlantic, north of the Bahamas, according to the old Bill Gray article (see his Figure 1, link given in #80), shows little temperature response to changes in thermohaline circulation strength. So, if the PDI changes are due to changes in the thermohaline strength, then a non-correlation with the western Atlantic is not surprising.

David Smith

Here’s a link to a diagram of the thermohaline conveyor belt.

I don’t know about the Guyana situation but do note that inclusion of that region (6N to 10N, hard to justify in my eyes) in Emanuel’s SST box helps his correlation.

link

bender

Ok, I’ve scanned through Mann & Emanuel (2006) and I think that (1) their argument has been somewhat misunderstood or misrepresented, in part because (2) their argument (as usual for the HT) is quite tortuous. [This in part because of their writing style, tending to reduce complex propositions down to simple, digestible sound bites, but also because of the hair-splitting nature of the fundamental detection and attribution problem. If a warming trend is overlain by massive cycles and noise, then you have to realize that an AGW attribution discussion is going to focus on that sliver of the pie, ignoring the larger questions about the whole pie.]

M&E06 do not dismiss AMO. They say that “the SST variability underlying increased Atlantic tropical cyclone activity appears unrelated to the AMO.” This is a very tricky statement to decode. It means something very precise, but, like all mathematical propositions expressed in ambiguous English language, is highly vulnerable to misinterpretation. Misinterpretation by EITHER side of the debate.

Of course, there’s more than one statement in the paper, and so there’s more to be said … later.

For now I would suggest that Judith Curry’s skill in linguistics, semantics, & debate could be useful in coming to a deeper appreciation for what these various papers really mean. As far as I can tell the major difference between them is the degree of non-scientific alarmism they choose to inject into the analysis and/or portray in the discussion. (Which is a pity. I mean, how much more divisiveness can the nation tolerate? Is this the new normal?)

Ken Fritsch

re: #96

Bender your impression of the E&M paper was strikingly similar the one I took away but could not confidentally voice until someone more knowledgable had more or less agreed.

E&M do not dismiss the existence of the AMO, but to me are saying that SST drives tropical storms and that the AMO residual temperature extracted from the global mean temperature is insignificant in the driving function. They in turn say that anthropogenic forcings, not global warming, is what is causing increasing tropical storms. Did not Mann previously write several papers on the AMO – and presumably not to show that it did not exist?

I would swear that when all is said and done that the effect AMO temperatures on tropical storms was what they extracted as a residual between the global mean temperature (ok maybe they detrended this) and the local temperature in the area of the AMO. They did some other statistical treatments, but essentially that is what I see them doing without them saying so. Their count of tropical storms was not correlated with the AMO residuals but with the increase in mean global temperature (antropogenic forcing was the term consistently used for global warming and I think done so to show that they consider that theory proven and a given) as, I guess, it projected onto the tropical storm area of interest.

Time out. Bring in Judith Curry and/or David Smith for a review or maybe Willis E will give it a go.

bender

A quick note on chain-link reasoning.

Suppose the following:
A=>B, r^2 = 0.3
B=>C, r^2 = 0.3
C=>D, r^2 = 0.3

Does it make sense to claim in absolute terms that A=>D? This would be tendentious, to use a TCOism. And yet that is more or less what they are doing in this paper.

As a kid, when playing with plasticine, did you ever try making a chain by stringing together a sequence of links? If you did, then you know how strong those kinds of chains are. They’re fun to build precisely because they’re so fragile.

Let’s talk about this.

David Smith

Judith, of all the many comments posted here, to me the most significant, by far, is Willis’ chart in #66.

I believe that what he did was correlate Atlantic PDI versus sea regions around the world.

I believe that what it shows is that PDI (presumably ACE, too) is negatively correlated with Pacific equatorial temperature. When La Nina is around, PDI is up. When El nino is around, PDI is down. not a surprise.

More interesting to me is the area off Spain, and southeast of South Africa. Those almost look like the fingerprints of a strong thermohaline circulation. Upwelling in the Southern Ocean, warm SST in the eastern Atlantic. Strong thermohaline correlation with PDI?

I’m very interested in your thoughts on this, when you have time.

Thanks

Judith Curry

re #102 David, the correlation between PDI (or NCAT45 or whatever) with SST is misleading. For example, ENSO’s influence generally gives rise to negative correlation with SST, esp in the NATL. THe Hoyos et al. paper addressed this issue (reminder, it can be found at)
http://webster.eas.gatech.edu/onlinepapers.html
(second paper on this list)

It is shared information in the trend, rather than correlation on a seasonal basis that is the important relationship. In my opinion, the Hoyos et al. is the most important paper to date on the hurricane/sst/global warming topic, would be very interested in any comments from the climateauditors on this

By the way, next tues afternoon, the topic of discussion for the Hurricane Seminar class at Georgia Tech will be the climateaudit posts on the statistical analysis of the emanuel and webster papers

bender

the topic of discussion for the Hurricane Seminar class at Georgia Tech will be the climateaudit posts on the statistical analysis of the emanuel and webster papers

I’m not sure what is the most productive way to discuss a blogospheric work in progress. Especially in a 1-2 hour seminar. It would be sort of like an unannounced site visit – walking into someone’s lab and criticizing the equipment, the layout, the students, their projects, the work ethic … without listening, and looking down the road at what the lab is capable and likely of producing. I would hope that the seminar approach would not be the same as that of a discussion group that is used to focusing on published papers. Because you know in advance where that’s headed. CA works in progress are not published papers. Treating them as such would be silly and naive.

Recognize, student hurricanologists, that it’s not about hurricanes! It’s about a new free and democratic way of doing policy-oriented science. A way that is still evolving. Yes, the Open Audit model is a clear threat to ivory towers as we know them. That is the idea. Lots of people are going to find fault with it. Especially those with a vested interest in maintaining a monopoly on the scientific marketplace of ideas. If you love science, you love open audit.

If you are attending, Judith, let me know how it goes. Just don’t tell them bender is a Gator.

bender

Re #105
So much to comment on, so much more yet to read … life is unfairly time-limited …

I think Willis or Bender in a previous thread showed a strong mode of TC activity in the 10-20 year time frame, and I have seen this in my plots as well (in particular, something ca 20 years).

M&E06 Fig 1d shows this as well, only in this case using spectral analysis (which is mathematically related to autocorrelation analysis). 20y,10y,5y,3y – all four wavelengths are significant in their Fig 1d.

I showed that these are not only the hurricane spectral peaks, but that they are the temperature-hurricane cross-spectral peaks as well.

Attribution, like any taxonomic problem, is inherently problematic. You have a turbulent, fluid blend of greys and you want to pull out the blackest blacks and the whitest whites, and see what they’re correlated with, ignoring all that middle ground complexity. Taken too far, it’s not climate science anymore – it’s witch-hunting.

With hurricane-temperature cross-spectral coherence occurring at multiple frequencies, you have to ask about the wisdom of demarcation. Do we really want an answer to the question “Is GW increasing hurricane intensity?”? Or do we just want better hurricane policy? We know what the AGW alarmists want. Do we want their brand of science dictating hurricane policy?

Politics aside, there’s much to discuss about analytical methods …

bender

Re #109
I would think a discussion on the role of “open audit” in a brave new internet-based world of international free science might be in keeping with Climate Audit’s purpose. But I think the hurricane thing may have strayed a little far from Steve’s core interests. He’s been all too patient thus far.

TCO

I think a good group can rip a paper to shreds better then they can an in-process discussion. That said, watching the ripping being done here, may make the class participate more critically themselves. Would be very interested in their comments on the technical issues themselves and not purely on process. I think it’s hard to comment thoughtfully on the alternate process of blogospheric work unless you have done the hard core publishing yourself (for comparison).

Ken Fritsch

Finally, while I think what Judy is doing here is very interesting and I look forward to its outcome, I would suggest to you that most scientists would tend to consider this particular forum biased and so not the best place to participate.

Thanks much Steve B for your unbiased opinion.

bender

This forum appears to be biased towards opening up the science so that it is transparent and accountable. I *thought* these were deeply held democratic principles in this country. I’m pretty sure they used to be.

Barclay E. MacDonald

“Regarding your “Open Audit” idea, I would point out to you that many scientists may not be thrilled at the idea of having to spend a lot of time refuting arguments from non-scientists or even from scientists in different fields.”

I suspect that is true, but to the extent they are paid and/or financed by those non-scientists, and those non-scientists are expected to pick up the bill on their recommendations, the non-scientists are entitled, at the very least, to full and complete disclosure of data and methods, and such questions must be answered. It’s too bad that it’s inconvenient!

Willis Eschenbach

Re #105, Judith, the Mann-Emanuel use of the global SST to detrend the AMO, versus using a linear trend, is a red herring. There is very little difference between the two. Here’s the comparison:

As you can see, the difference is very small.

w.

Judith Curry

Re #106 Bender (Gator!)

Re the class discussion, we will be focusing on the statistical and scientific issues raised on the bender/willis hurricane threads since mid Aug.

In this forum, we won’t be focusing on the blogospheric process or the greater implications of climateaudit, although this may come up in discussion (will be interesting to see how the students perceive all this).

Re #114 Steve, you bring up an interesting issue as to why more scientists dont blog generally, or don’t post on climateaudit specifically.
A year ago, i wasn’t sure exactly what a blog was, and I had never visited a blog. I began visiting various blogs post WHCC, motivated by emails that i received that referred to specific trashfests of WHCC (scientific and personal). My first ever blog was posted on this thread
http://mustelid.blogspot.com/2005/10/ your-comment-was-denied-for.html (watch out for the space i inserted)
The next blog that came to my attention was prometheus, RP Jr was attacking a number of us on the hurricane/global warming circuit fairly regularly. Then i started reading RC and linking to some of the links posted on the RC site. When we published the BAMS article, we decided not to do a press release, but i did follow what was going on the blogosphere re the paper, and I posted to about 4 different sites. I happened upon climateaudit somehow in this process, I had never heard of climateaudit before. I posted my first message, and then asked myself why i hadn’t come across this blog before, say through RC links (ha ha). then i spotted SteveM’s name, and figured out where I was. I was enjoying the interaction and spent some time trying to figure out what climateaudit was all about. I applaud the general principles behind what you are doing. Further I am quite intrigued by what is going on in the blogosphere generally, and at reaclimate in particular. it is a very interesting experiment. It is interesting and worthwhile, and I have continued to blog here (I am not blogging much anywhere alse at present). I try to keep an open mind an think outside the box, participating in climateaudit has been provocative and interesting. At first on dlimateaudit i was getting “attacked” a bit, but overall i have been well treated and respected by the other bloggers and the attacks are pretty much disappearing at this point.

So why don’t more scientists participate? General ignorance about the blogosphere, not enough time. There are also alot of ad hominem and other kinds of attacks on the blogosphere, which scientists typically do not want to subject themselves to. Specifically with regards to climateaudit, most scientists of the “warmer” persuasion that are into blogging spend time at RC, which matches their worldview (sort of for the same reason people watch FOXNEWS versus PBS Lehrer). There is also probably an element of “fear” regarding what happened to Mike Mann, and that is somehow “blamed” on MM (the main issues of concern were subpoena of personal financial records and other things that were pure intimidation by the federal govt, and had nothing directly to do with MM) and this is somehow connected to climateaudit.

I am thinking about writing a paper on “spinning climate science in the blogosphere”, there are alot of interesting issues here.

I will also be interested in the perception of the students of climateaudit (they probably don’t know the history of RC and climateaudit origins).

bender

Re #122
If there’s anything I can do to faciliate the discussion, let me know. If there are unanswered questions at the end of it all (which there usually are), please record them, and I’d be happy to take a crack at answering them. I’m definitely not the best analyst around; I’ve met plenty better than me. But I’m here and willing to help if I can. We could even post the Q&A at CA if that’s ok with Steve M.

On the one hand, I really don’t have time for this. OTOH human society is starting a new chapter in the annals of science – using the internet to connect human brains with multiple datasets & algorithms to attain full parallel processing in the application of the scientific method – and that is once-in-a-lifetime exciting. If I’m trashed by your students, it’s for the greater good. Good for science. Good for policy.

Thanks for the link. For the record, it was Steve Sadlov at CA who pointed out the BAMS article to us. The only reason it perturbed me was that the time-series in Fig. 1 had no error associated with it. Like the IPCC hockey stick. It made me wonder if scientific standards in climatology are back-sliding. And now we have this uncertainty-free Fig. 5 of Hansen’s. These quotes by Schneider. Policy makers must be forced by scientists to embrace uncertainty. We have to show them how and why it matters, and figure out what to do about it.

bender

The #122-#123 exchange, to me, is symbolic and helps to appreciate the depth of the problem. Between the scientist and the policy-maker is this huge gap. The public and the elected officals don’t understand how big it is, but the bridge-builders sure do. As a scientist, as a policy-maker, if you try to bridge it you risk falling in. So there’s fearful cross-talk from the precipice. Messages are distorted. People get frustrated. Progress is slow. Finger-pointing, rock-throwing, skirmishes. Language devolves as adversaries reinvent it in their own image. Communication stops.

At some point the collaborative effort needs to start. Scientists and policy-makers each need to be rewarded for bridging efforts. That will require a major shift in how governments and universities function. (e.g. “Publish or perish” is not serving the taxpayer well. Partisan ownership of a policy stance is not serving the voters well.) Responsible, accountable science-based policy will require a new culture of reaching out and working together. That is what the business community is asking for. That is what the taxpayers are asking for.

Policy-makers, please follow RPJr’s model and accept the uncertain nature of science.
Scientists, please follow JC’s model and seek more transparent and accountable methods for generating and communicating policy-relevant results.

Steve McIntyre

You mentioned the financial requests by the House E&C Committee. This is a classic example of two different worlds as I’m 100% convinced that the request was merely pro forma without any special interest in that particular topic.

Their key questions pertained to disclosure i.e. did Mann calculate the verification r2? the results without bristlecones? etc. They never did get an answer to their questions. Mann’s response to the NAS Panel was untrue and the panel didn’t pursue the matter. By the time that Mann got to the House E&C committee, no one had defended him so they didn’t bother with him. Had they still been interested in the question, Mann would have been in a very uncomfortable situation. The question about the failure to report the failed verification r2 statistics remains quite relevant as I doubt that Mann’s study would ever have obtained the following that it did, had he reported the failed statistics.

Steve Bloom

Re #126: This causes me to wonder if you’ve ever dealt with policy-makers.

Re #127: “You are more than a disinterested party in this, no?” As are you, Roger. Not an “honest broker” in sight, it seems (as you define the term, anyway).

Judith Curry

Re #126 Bender, thank you for this analysis, I agree.

bender

One more test. Humor me.
“ampersand”-“less than”-“minus” yields:

y &

bender

Re #73

you can input the lt sign by using the tex operator

Steve M, I saw the same message posted to Willis a couple of weeks ago, but didn’t understand it then, and still don’t now. Moreover I can’t find the full instructions on using this “tex operator”. It’s driving me bonkers.

[Failed test in #134 can be deleted.]

Steve McIntyre

#136. Latex option is described here. http://www.climateaudit.org/?p=660 It’s very handy although it may not do what you want to do.

Willis Eschenbach

Re #131, Judith, as always your comments on the Michael Mann / Congressional situation were interesting. You say:

The point I make is that the broader scientific community was totally taken aback by the subpoena of his personal financial records

Context is crucial in this issue. The committee’s request, not a subpoena but a request, asked him politely to “please provide the following information” (along with other scientific information about his data, methods, and results):

1. Your curriculum vitae, including, but not limited to, a list of all studies relating to climate
change research for which you were an author or co-author and the source of funding for
those studies.

2. List all financial support you have received related to your research, including, but not
limited to, all private, state, and federal assistance, grants, contracts (including subgrants
or subcontracts), or other financial awards or honoraria.

3. Regarding all such work involving federal grants or funding support under which you
were a recipient of funding or principal investigator, provide all agreements relating to
those underlying grants or funding, including, but not limited to, any provisions,
adjustments, or exceptions made in the agreements relating to the dissemination and
sharing of research results.

Now, the question of who is paying for the research is a question that has gained great prominence in climate science. Steve M. gets asked these kinds of questions all the time. Heck, I’ve even been asked who pays for my research … the answer being, “I do” …

However, in the case of Michael M., I and many other, including Joe Barton, it seems, were incensed by his refusal to reveal work which taxpayer dollars had paid for. He was being paid by the US Government to do climate research, and then hiding the results. In that case, it is entirely appropriate, in my view, for the US Government to find out what research he has done on the public dole, and what he has done with the results.

In order to find this out, however, it is not enough to ask him which research was publically funded, as he is known to … ummm … well, let me just say be parsimonious with the truth. To find out from him, it is necessary to ask who funded all of his climate research, otherwise, he might accedentally put some of the answers in the “CENSORED” file … (if you don’t know the history of that file, it is where Michael Mann put the paleoclimate “hockeystick” results that he did not want to see the light of day).

In that situation, I have no problem with the Committe asking Michael Mann “Who paid for your climate research?” What’s the problem with that? Would you be unwilling to reveal who paid for your research?

w.

PS – at the end of the day, he provided the financial information, none of which was embarassing, and only part of the scientific information, much of which was embarrassing …

Pat Frank

#122,125,128,139,140,141 — Richard Lindzen has pointed out that when he was hauled before the committee of then-senator Gore in 1992 and was “bullied” (Lindzen’s word) to change his mind about the cause of recent climate warming, mentioned here, no scientists came to his defense.

Nor, apparently, was the scientific community chilled by that particular bit of Congressional persecution. The fearful response seems to be a little selective. Lindzen has been competely transparent with respect to his science, in rather stark contrast to Michael Mann or Phil Jones, or the IPCC for that matter, and further tens of billions of dollars aren’t being leveraged by his work. Why shouldn’t Congress be interested?

What I don’t understand is why the same scientists that have responded sympathetically to Mann haven’t also advised him to release his methodologies. That makes their defense look partisan, and the partisan defense of an obscurant is not ethical scientific practice.

I think Mann deserves no defense, Judith. His actions have not been forthcoming. For that reason, I think Barton’s requests for information should warrant no fear. Barton would have had no reason to make a request had Michael Mann been open about his work. One may also note that in the context of the Baltimore hearings, Barton’s requests were entirely in keeping with usual Congressional activities regarding the auditing of suspect publicly funded science.

Willis Eschenbach

bender, you say:

I think Judith’s main point is that there is a legitimate fear among scientists that their research could get sidelined and their credibility could take an unnecessary hit if they were to be subpoenaed in this way.

Describing the fear as “legitimate” assumes facts not in evidence …

1) Michael Mann’s research (unfortunately) did not get sidelined.

2) Michael Mann’s credibility (unfortunately) did not take a hit.

If that’s what happens when you defy the Committee’s request to come clean, what’s there to worry about?

w.

bender

Re #144
I’m not so sure about that, Willis. Maybe it’s in how you define “sidelined” and “credibility hit”? As for legitimacy of fear, my point was that when you don’t know your enemy, it is in some sense “legitimate” to be fearful.

Bottom line for any fearful scientist is if you are open with your data, and methods, and funding sources, careful in your work, admit when you’ve made an error, then you never have anything to worry about.

Worth noting that the financial information that the committee asked for was not onerous to prepare. It’s the sort of information contained in any NSF grant, for example. It’s a 2-minute copy and paste job.

David Smith

Judith, concerning the tropics, I have a question. I am stumped by the water vapor trends in the tropical atmosphere.

Linked here is a trend of the specific humidity at 400mb (about 5 or 6 miles above the surface, high cloud level). This is for the world’s tropical region (25N to 25S). The humidity trend is definitely downward. Similarly, this 400mb trend is seen at the other levels above 700mb upwards (in other words, much of the troposphere).

Linked here is a trend of the specific humidity at 925mb (near the surface) for the same region. In recent years, the humidity trend is up.

I understand why the near-ground humidity rises (warmer sea temperatures mean more evaporation) but I do not understand why that moisture does not mix upwards in the tropics. Any idea why?

And, do you know if declines in the water vapor content of the mid and upper troposphere is predicted by the GCMs? I thought the prediction is for rising humidity (=more greenhouse gases) throughout the atmosphere, not just near the ground.

Thanks,

David

Pat Frank

#149 — On the contrary. Having been around academic scientists and PhD candidates my entire adult life, I can say with confidence that virtually every personality type is included among them (except perhaps the violence-driven). They do not “tend to have private personalities.”

No one likes to have a favored idea wrecked. But we all have to swallow hard and carry on if that happens. That’s happened to me. I’ve perhaps brought that circumstance upon others. Judith Curry is strong-minded to be here amongst critics, it’s true. After looking at the links RP jr. provided in #127, however, it’s clear that Judith has the stomach for engaging controversy. She has also responded very well; even offering to co-author a paper with Bender (I hope that happens).

Reconciling contrary interpretations through a collaboration with an opposed-view colleague happens with some regularity in science, and is a great way to facilitate real progress. I’ve done it myself, and successfully. It is a perfect out-working of the scientific ethic of disinterested objective knowledge. Judy Curry has it. Michael Mann and Phil Jones, by all evidence, do not. Those who collaborate with them under that circumstance, or who protect them, are guilty of participatory subversion of that ethic.

TCO

Pat, I been around the union carders. Been in the military, Wall Street, etc. There are a lot of different types of peoples and tendancies for groupings. We are not all the same and personalities are not distributed across fields the same. That there is a wide variance is irrelevant. I’m talking about the field versus other fields. So mean and sigma are what matter.

bender

Re #151 Nice dodge, as usual, Bloom.

David Smith

There is something else climate-wise that stumps me.

Linked here is a plot of global air temperature in the upper regions of the troposphere (200mb, meaning that about 80% of the earth’s atmosphere lies below this level).

Notice the dramatic change in temperature circa 1976. This pattern (anomalous temperature rise) is also seen from the top of the stratosphere all the way down to about 700mb (10,000 feet above sea level).

Something major happened to Earth’s atmosphere in 1976. Not only did the mid and upper atmosphere warm sharply, but global surface temperatures stopped declining and began to rise.

This 1976 inflection point is reflected in other atmospheric parameters, like geopotential heights, so I do not see it as a measurement issue. Something big happened in 1976. But what?

The effect is especially evident in the stratosphere.

I’ve heard that the pre-1976 cooling was due to aerosols. It is hard for me to imagine how reduced aerosols could cause a jump like the one we see in the records. I’d expect a gradual shift from cooling to warming as aerosols waned.

Now, the stratosphere can undergo sudden warmings related to things called gravity waves, which I believe are vertically-propogated slow-moving waves. But, my understanding is that those events are relatively short-lived. Whatever happened in the mid 1970s has lasted a long time.

Perhaps someone has figured this out, and I’ve just missed hearing the explanation. If I was a climate scientist, I’d be intellectually “stuck” on this question until I figured it out.

bender, you’re a gator, I see. See you guys October 7!

David

David Smith

Re #157

I’m sorry, here is the correct link.

David Archibald

Re 156, a number of things changed in 1976. Certain fisheries had dramatic changes in yield. Perth’s weather became drier after 1976.

bkc

Re. 156

Something big happened in 1976. But what?

No idea if it’s related or not, but I believe the PDO shifted states around ’76 or ’77 to the “warm” phase, and I believe it has mostly been in that state since. Interesting how it tracks global temps (or vice versa) – rising in the 30’s and early 40’s, cooling in the 50’s and 60’s, and warming again in the 70’s to present (mostly)… Link for index is here.

bkc

Re. 160

I think there have been several studies linking fish yields to PDO phase state, at least in NE Pacific. Don’t have any links offhand.

bkc

Re. 165

Being statistically challenged, I can’t really comment on the quality of the statistical analysis. However, here is a typical study – ***WARNING – CONTAINS PCA***. It also, however, had this encouraging comment; “Further, the detection of trends without smoothing tends to lend greater weight to such interpretations of the data.” Also, he provides links to data and plots of all data series.

Here is an overview of the PDA (same author), with climatic and biologic responses, and many references.

Judith Curry

Steve, for the record I agree absolutely with you that scientistst MUST:
1. make data publicly available
2. document upon publication the methods used in the research so that the results are reproducible
3. answer questions regarding the data/methods from anyone seriously trying to reproduce the results
4. disclose funding

If this is not happening (and it seems not to be), the blame is on the funding agencies, public institutions that employ the scientists, and the scientific journals. Individuals may try to skate around this accountability, but these other groups have the power to insist through not funding, not promoting, not publishing, etc those who fail consistently to provide this accountability. However, government intimidation of scientists (Mann, Lindzen, whoever) is a bad thing.

welikerocks

The government made Steve and Ross’ findings official and on the record because to these scientists and their funders and backers, Steve and Ross were just pests and amatuers. The government represents me in this case. The scientists who believe in AGW , their backers, magazines and media who promote only their beliefs intimidate me! Without government representation or audit in this case, where would I be?

Hello Bender,
Some thing Steve Bloom said in another topic spurred me to a google search for new publications (I found so many) Apologies if this one has already been discussed but I wanted to show it just in case not.:

Public release date: 11-Sep-2006
Human activities are boosting ocean temperatures in areas where hurricanes form, new study finds. “We’ve used virtually all the world’s climate models to study the causes of SST changes in hurricane formation regions,” Santer says.
Title: “Forced and unforced ocean temperature changes in Atlantic and Pacific tropical cyclogenesis regions”
Authors: B.D. Santer, T.M.L. Wigley, P.J. Gleckler, C. Bonfils, M.F. Wehner, K. AchutaRao, T.P. Barnett, J.S. Boyle, W. Brueggemann, M. Fiorino, N. Gillett, J.E. Hansen, P.D. Jones, S.A. Klein, G.A. Meehl, S.C.B. Raper, R.W. Reynolds, K.E. Taylor, and W.M. Washington.
http://www.eurekalert.org/pub_releases/2006-09/ncfa-haa090706.php

Judith Curry

Re #117 Willis, I absolutely agree with you that there is uncertainty in the attribution of the 1940-1970 cooling. My recent (post Feb acceptance of the BAMS article) oral presentations on the issue of hurricanes and global warming cite as the two main uncertainties in the link as: the quality of the hurricane data, and attribution of the 1940-1970 cooling. I am stumped on the attribution of the cooling. RP Sr recently posted a link regarding Judith Lean’s presentation at the SORCE meeting on solar variations in the last century, and the impact of solar forcing in the past century seems to just get smaller. Sounds crazy, but I am starting to ponder the WW effect. We discussed this in a previous post re the 1915 minima in NATL TC activity (my argument was that this was associated with minima in SST also, lending credibility to the TC minima). Look at Willis’ plot, and if you take out the WWII years in the NH, then you don’t get the big warm spot in the 30s-40s. Mike McCracken made the point at my latest presentation at the Climate Institute that WWII was a major perturbation to the weather observing systems in the NH, including the methods of how SST was measured by ships (apparently he has been looking into this a bit). If WWI had a similar impact on observations, not sure what this means in terms of the reliability of the historical record. Maybe we need to look more closely at the proxies for the “historical” part of the climate record (no bristlecones please). And we need to take a careful look at ice core and other records that can help us assess how much volcanic and pollution aerosol was present and where did it go.

Judith Curry

Re #170: The Santer paper didn’t have anything to do with hurricanes, contrary to the press releases and interviews. They concluded from all of the coupled global climate model runs that tropical SST variations over the last century have been externally forced, not associated with internal oscillations. This then begs the question of the attribution of the forcing, and it doesn’t help us understand anything about hurricanes. This paper did help (slightly) to tighten up the link in in the hurricane-AGW causal chain whereby they ostensibly ruled out natural internal variability as a cause of the tropical SST increase (their experimental design could not rule out natural forced variability). So why the hype in the press release and the interviews. in my opinion, this was inappropriate in the context of the scientific findings of this particular paper.

bender

Re #170
Thanks for the paper. I’m very far from being an expert in this field. My only beef was with the trend analysis methods of Emanuel (2005). From Mann & Emanuel (2006) I conclude that the field has “moved on” toward more sophisticated methods of detection and attribution. Which is good and necessary. Maybe Emanuel (2005) was just a baby-step forward.

The Santer et al. paper, from the press release, appears to be another example of that “moving on”. In many ways my criticisms of Emanuel (2005) are rendered irrelevant, because the field obviously developed a more nuanced approach to ‘fingerprint’ detection. IOW it is no longer a case of trend detection. That means the approaches have gotten more difficult to understand and to audit. Consider that this paper was authored by 19, count ’em, brains. That’s a lot of “moving on” firepower.

For the sake of the yellowjacket hurricane seminar class (IOW to cover my shiny metal ass), it is important to realize that a global forcing effect will not necessarily result in simple, ocean-scale fingerprints, like a linear trend in SST. You increase the temperature of the burner under your soup pot, and all kinds of new circulation patterns will arise that you never would be able to predict. If you do the experiment slowly enough I would imagine that pre-existing circulations would first be enhanced, in terms of temperatures and flow rates through them, before there are qualitative changes in circulation. If that’s an analog for the globe, it means that circulation features like the AMO, or what have you, will become strengthened under warming as pathways of heat dissipation. If that pathway is intermittent, then the detection model has to allow for intermittency. Hence the need for more realistic temperature-response models. Hence the validity of the easily-overblown, but symbolic, term ‘fingerpint’ detection.

I think that that is what the field is moving toward: more sophisticated models of cause-and-effect, so that we are better able to detect these complex responses to rising temperature. One approach is to use process-based models of cause & effct: Santer et al. 2006. Another is better statistical models that allow for complexity in the background processes which are expected to be affected by GW: Mann & Emanuel 2006. Both are valid, complementary approaches.

The question before us is whether the conclusions of these papers are robust. Whether their methods work ‘as advertised’. That would take quite some time for someone like me, a non-specialist, to answer. Whereas I could see the flaws in Emanuel’s paper on first inspection, it was largely because the approach was quite simple. Not so with these other papers.

To summarize. The field has moved on. My criticisms of Emanuel (2005) are valid, but no longer relevant. It will take quite a bit of work to figure out if the new conclusions of these newer papers actually do follow from the new methods. The methods look reasonable. Yet we know how fragile these computer-intensive methods are to computer bugs and human error. I hope these weaknesses are recognized so that the researchers will welcome an open auditing process.

I think one thing all these papers ought to do is to end with a clear statement as to what they believe is the marginal impact of warming (GW & AGW) over and above the background of normal variability. In the case of a trend, that’s easily done in a sentence. In the case of a more nuanced temperature response, you need a comparative graph: hurricane frequency with & without GW, and also without A under AGW hypothesis. Three lines. A paragraph won’t do. That will put the sliver of AGW in context with all the other non-GW related variability that’s occurring. Which is RPJr’s point. If AGW is causing an extra hurricane or two per year (but delivered in pulses of 3-4 during active seasons), but no detectable increase in landfalling hurricanes, does it make sense to take drastic action against GHG? Or should we just tinker with insurance rates & mechanisms?

That, to me, is objective science that draws a line between hurricane/AGW alarmism vs. policy-useful hurricane science.

This assessment is probably quite naive from the hurricanologist’s perspective. That’s ok. Feedback welcome.

bender

Re #173

there are some teleconnections (cross basin stuff) involved in hurricane genesis

Do you mean like I suggest in #103? Has these been hypothesized or proven yet? IOW do we have a novel result here?

bender

Re #179
Which came first – the chicken or the egg?

fFreddy

Re #177, bender
Yes, all right.
However, for the avoidance of doubt, I should just point out that my somewhat intemperate terminology in #175 was directed at whoever originated the story. There is no question in my mind that Dr Curry was only repeating what she believed to be true.

BKC

#180

I don’t know. Which came first, the ’98 El Nino or the global average temperature spike?

bender

Re #184
Exactly.

If the hypothesis is that AGW creates a global ‘fingerprint’ then you’re going to have a tough time detecting it – because a priori you don’t know what this ‘fingerprint’ looks like! All you know is it’s not global, and it’s not a trend. Which is saying almost nothing at all, really. So we start looking for ‘fingerprints’, knowing only that they look alot like everything else out there on the globe. Needle in the haystack? At first you’re going to see fingerprints everywhere, or nowhere, depending on whether you’re a proponent, or a skeptic. Over time the true nature of the ‘fingerprint’ will reveal itself. Until then detection will continue to be a serious problem.

Start boning up on your GCMs. They are the tool that will be used to define, detect, and quantify these ‘fingerprints’.

bender

Re #185
Interesting, as this fits well with Willis’ #66 correlation. The windshear mechanism is obviously well understood physically, but is the (-) correlation of Atl PDI to Pac SST a novel result?

Steve Sadlov

RE: # 149 – “I hate the calcification of science that has come with all the money that poured in after ww2.”

Me too.

BKC

#186

All you know is it’s not global, and it’s not a trend

I guess I’m confused. I thought the “trend” in global temperatures since the ’70s was one of the pillars holding up AGW theory.

Needle in the haystack?

Yes.

I guess my point is, El Nino and the PDO have been around a long time (before industrialization). A natural climatic osillation (El Nino) can obviously affect our metric of (A)GW – global average temperature. Maybe another natural climatic oscillation (the PDO) is also temporarily raising the global average temperature, and AGW is getting the blame for it.

AGW may affect the timing or intensity of the PDO but, as you say, the fingerprint will be very difficult to detect.

Start boning up on your GCMs. They are the tool that will be used to define, detect, and quantify these “fingerprints’.

Until GCMs can predict the timing and intensity of El Nino, the PDO, etc., I don’t think we can trust them to find the signature of AGW.

Pat Frank

#190 — “RE: # 149 – “I hate the calcification of science that has come with all the money that poured in after ww2.”

Me too.”

What calcification of science? Since WWII, science has been wildly productive and remains so.

BKC

#193

Ok, I understand your point. (I think)

If I may use you analogy to explain (or maybe confuse) my point?
Everyone believes AGW robbed the bank and are trying to drum up evidence to convict (they currently only have a circumstantial case), when in fact, (s)he only picked up some of the money that the real thief (PDO) dropped on his way out the door.

AGW has been arrested, and there’s a crowd outside the jail clamoring to…

uh, well, you get the picture:)

bender

Re #196 Yes. PDO and AGW share the stash, and sometimes even wear the same clothes, so it’s hard to distinguish them (detection) and to apportion blame (attribution). Is AGW the mastermind (including master of disguise) or just an accomplice?

TCO

161. Sorry, for the offenses Steve. I stopped posting when I saw it. My “time out” is over now, so I’m back here to play…

Steve Bloom

Re #196/8: I’m afraid there were multiple witnesses who observed PDO at home in bed with a full body cast at the time of the robbery.

David Smith

I hope Steve starts a new thread for Santer and other papers in general. I have some comments (later) on this one as well as a couple of other papers, including Hoyos.

A bit off-topic for a moment, there was an earlier discussion, somewhere, about the fingerprints of global warming. One fingerprint which I accept is shown in the chart here.

This is a proxy for the global height of the troposphere. It is the pressure layer at which the troposphere ends (and tropopause begins).

As the troposphere warms, it expands. The only direction it can expand is upwards.

(Now, the chart is reversed, meaning that a warming and expanding troposphere will push the chart line downwards. That is a bit confusing until one’s eyes adjust to it.)

You can see the trend towards a warmer troposphere that began in the 1970s. You can see cooling from a volcano about 1984 and again in the early 1990s, and you can the El Nino in 1998.

Since 1998 the rate of rise appears to have slowed.

Now, what about the pre-1960 part? I don’t know if that is a data problem (this is from radiosondes, which was a rather new technology, and the global coverage may have been poor outside North America and Europe) or not. I tend to discount that data.

I think this plot is consistent with the satellite-derived temperature plots and less so with the reported ground station trends.

So, in my personal list of GW fingerprints and things to watch, I put tropopause height.

David

David Smith

Re #205

If I was a grad student, or had grad students looking for projects, I’d research whether radiosonde readings were credible prior to 1955.

If they were credible, if they had sufficent global coverage and accuracy, then I’d say that is a piece of evidence that says that the 1950s troposphere was pretty warm, maybe about like the current period.

Barney Frank

#202,

I’m afraid there were multiple witnesses who observed PDO at home in bed with a full body cast at the time of the robbery.

Yeah, multiple paid informants with a lot riding on AGW taking the rap.

Steve Bloom

Re #208: OK, Barney, describe for us exactly how it is the PDO could have had the effect being speculated on. Focus on the heat flux issue, please.

Pat Frank

#211 — Willis shows his work, Steve B. You merely pronounce.

Pat Frank

#213 — glad you agree.

David Smith

Judith, here are a few comments on Hoyos et al (linked here , if you’re still around this cyberspace.

The paper looks for trends in factors other than SST which might account for the reported global increase in category 4 and 5 hurricanes. (Note: the key assumption is that storm count (NCAT45) has increased, which is a question under debate, but I accept it as fact here.)

The paper uses an interesting approach (a technique from information theory, with equations from Claude Shannon) which I cannot comment about due to my lack of understanding. (I saw nothing in the results that raised my eyebrows, so my assumption and belief are that the approach is fine.)

The paper reports that, while variability in the factors it checked (humidity, wind shear, stretching deformation) affect hurricane intensity over short periods (like seasons) there is no long-term trend evident in those factors that would account for an increase in NCAT45.

It is a well-written paper with nothing I’d consider a sleight-of-hand or aimed to grab headlines. Unlike Emanuel’s papers, there is no “hmmm” factor in this paper.

Here are my comments:

* First, my physical basis for what’s being examined. (I always need a physical model in my head before I can make sense of something.) A NCAT45 hurricane has:
1. a SST of at least 28C;
2. moist, unencumbered inflow at 850mb and below;
3. no major intrusion of dry air at midlevels;
4. low windshear of the storm envelope using 700mb-500mb-300mb-200mb levels, so that the center is vertically stacked and not significantly tilted;
5. at 200mb a broad anticyclonic environment so that the storm can establish an unencumbered outflow;
6. and at least one excellent outflow channel.

* Hoyos et al looks at humidity in a 925mb to 500 mb level, and sees no trend. I would have broken that in two and looked at humidity trend at the 925+850mb levels and also the 700+600+500mb levels.
The first grouping is the primary inflow region, and I bet the specific humidities there have trended upward. That is no surprise to me, as the humidiities in these lowest parts of the atmosphere have probably increased as SST have increased.
The second group is a low-inflow region for a storm, and doesn’t play a major role unless there is dry air entering and disrupting the convection and thermal structure. From what I’ve seen, there may be a trend towards drier air, which is probably a mildly negative factor for NCAT45.

In my opinion, if a trend other than SST exists, it will be in #4, #5 and #6.

Hoyos uses the standard windshear meansure of 850mb to 200mb. To me, that is useful as a tool for examining genesis potential but its value drops when looking at strong hurricanes. Many a potential major hurricane has been disrupted by shear in the 300mb or 400mb levels.
For researching NCAT45 storms, I would try to look at shear across a 200-300mb, 300-400mb, 400-500mb and 200-500mb environments and see if trends exist.

That is an enormous task, I realize, and perhaps more importantly, I question the accuracy of the available data. These are sparsley-sampled regions which also tend to be graveyards for dying, small-scale circulations in the mid and upper levels. It is fairly common, even today, for forecasters to be surprised by unexpected shear in the tropics. I would bet that, even in reanalysis, much of that reanalysis is from interpolation across large distances.

* stretching deformation at 850mb is something that I see as a useful tool when looking at storm genesis and did not have a lot of value when looking at whether a storm stays a category 23 or becomes a 45. I think that Dr. Webster is the expert on this, and he was part of the team, so there must have been a good reason for using it. I’d appreciate being pointed towards any papers that might be around to explain its applicability to intense storms.

* I’d tend to want to use the prime months of intense hurricanes, rather than the entire season. For example, in the Atlantic I’d use ASO, rather than June-October, because the ASO upper level environment is typically different from the June-July and October patterns.

* I have no clue as to how to examine available data for a trend in outflow channels

Good paper! I applaud the search and hope it continues with a more-detailed look at upper level trends.

bender

Here is one for the GT hurricane seminar class to discuss tomorrow. These are the results of an ARMA(1,1) fit to Emanuel’s PDI series:

Coefficients:
__ar1__ _ma1_ intercept
-0.5957 0.7940 10.5582
s.e. 0.2568 0.1838 0.9568

sigma^2 estimated as 39.93: log likelihood = -179.52, aic = 367.03

It was Steve M that first commented on this. He interpreted the AR lt 0 / MA gt 0 pattern as one of “anti-persistence”. I’d love to hear a reasonable physical interpretation. What would this mean to a hurricane seasonal forecaster? And what does it mean that the SST does NOT exhibit this anti-persistence pattern? [See his original post #22 in bender & Willis on Emanuel.]

Go Yellowjackets.

Judith Curry

will get back to you tomorrow eve after the hurricane class.

TAC

Judy, thank you for sharing your class comments with us. It is interesting, though a bit disheartening, to see how others perceive the debates here on CA.

I was a bit surprised on one technical point: Are you sure Student #2 said:

1. The climateauditors do not seem to understand parameteric vs nonparametric tests. The Kendall test (rank based test) used by WHCC does not require a normal distribution and is also fairly insensitive to serial correlation, so the emphasis on autocorrelation and distributions did not add anything.

I agree that the Kendall test provides robustness against non-normality. But are you sure it is robust with respect to serial correlation?

bender

Re #221
Very interesting, and, I hope rewarding for all involved. A follow-up might also be instructive and entertaining.

As Steve M points out, though, it’s multiproxy reconstruction science that is the focus of the blog and where serious improvements are needed. (The hurricane threads were a departure graciously permitted by Steve while he was busy traveling.) It would be great to do the same kind of thing with a tree-ring seminar group. Any open-minded instructors out there willing to experiment a little?

C’mon man, everyone’s doin’ it!

Barclay E. MacDonald

Judith, very interesting. Thank you for taking the time to do the post. And congratulations David Smith and Steve Bloom!

I do find the characterizations of the players ironic in light of the perceived unfairness of the opening comment of Bender about your piece and recognition of how it was corrected, but very interesting. I think I see the blog more as a process for discovering information than they do. But I appreciate their input, and will keep it in mind as I continue to lurk far in the background trying to learn and understand.

bender

Correction, friends, bender did not write that introduction. Go back and read. Careful with your detection & attribution algorithms. (See how the meme spreads?)

bender

1. The climateauditors do not seem to understand parameteric vs nonparametric tests. The Kendall test (rank based test) …

3. ARMA is a brute force method used when nothing is known about the physics.

How is Kendall going to help you describe the physics? Check out the resident hurricane expert for an example of what reasoning on the basis of Kendall gets you.

Steve McIntyre

RE the snippy comment about ARMA testing: I’ve found it handy to routinely do ARMA(1,1) tests of time series as a type of quality control. For example, last summer, I performed ARMA(1,1) tests on all the gridcells of Jones’ CRU data set; picked out extreme values; plotted a world map of the coefficients and almost instantly found some bad data that CRU’s quality control had missed e.g. one location intermittently had the decimal places in the wrong spot. I did the same thing this spring on the von Storch-Zorita pseudoproxy network and found problems with their sea-ice formation in the Waddell Sea. It’s not very highbrow, but it can be a very quick way of looking at a large data set. Obviously the originators hadn’t done these tests or they wouldn’t have had the defects.

bender

Re #232
AR(1) models were good enough for legendary dendrochronologist Hal Fritts. Does that mean he not understand the mechanics of plant growth?

Willis Eschenbach

Judith, thank you very much for your sharing of the class comments. The one I particularly loved was …

The students thought that the fact that the climateauditors did not have “external funding” to do this work diminished their credibility

Methinks I should put in for an Exxon grant to increase my credibility …

Your students’ characterization of me was half right. They said:

SteveM and Willis were perceived has hardcore statistical skeptics, assuming that all analyses done by climate people are suspect.

In fact, for me, all analyses are suspect, including my own. I’ve seen far too much garbage passed off as science to be anything but suspicious of all “scientific” studies, and I encourage your students to be the same. It was my Louisiana bayou grandmother who first pointed me in this direction by saying:

Child, you can believe half of what you see, a quarter of what you hear … and an eighth of what you say …

My very best to you and your students,

w.

PS – Like the others, I truly would like an example of a study that was demolished at the head of the thread, and then rehabilitated.

fFreddy

Attn: Student #2
I’m sorry that your review made you so hot under the collar. Now that it is completed, why not engage in the discussion here and show us where we are wrong ?

Proxy

Re: 233

Only a trillion dollar problem, oh then it’s not that serious. In a world economy of approximately $37 trillion it won’t cause excessive growth. There are plenty of companies able to build those CO2 extractors, coastal defenses, arctic coolers and relocate entire cities. Naturally taxes will have to increase a little 🙂

Judith Curry

A few clarifications motivated by your comments: The appreciation of Steve Bloom was associated with his defense of what climate researchers do (I was also puzzled by their characterization of Bender). The students (newcomers to the site) did not pick up on the essential proxy hockeystick focus of the site. The students regularly read realclimate, this is a good way for them to keep up with current topics in climate research (I think they mostly tend to read the initial post, and not go deeply into the blogging). Re #241, student #2, having gone through the entire Ph.D. process is definitely a fighter and well accustomed to defending his research, but found your points (re the hurricane stuff) not very interesting owing to lack of knowledge of the data and the physics. For the 1st and 2nd yr graduate students (and the undergrads), this was probably an education. The “attacks” that were of most concern were the personal ones, such as at the beginning of the thread where either my knowledge or motives were arguably attacked. the “black hole” was the black hole of time, the students did not see the importance of defending anything on this site (there was some concerned voiced about the inordinate amount of time i had spent blogging on the site), as opposed to other venues such as scientific conferences.

I chose to focus on climateaudit (as opposed to the other blogs) since I am intrigued by the “flat world” process of doing (or at least evaluating) science on the internet. I am also intrigued that there are so many people spending a huge amount of time doing research on these topics without any funding. I am somewhat surprised that the students were more “conservative” than me about blogging in general and this site in particular. It was an interesting experiment. I will continue to reflect on this.

Jean S

Judith, I found your students’ comments interesting and somewhat surprising. A think they do not seem to realize is that this site was founded on study of (and it’s main focus has been on) multiproxy temperature reconstructions, especially Mann’s work (only very recently there have been more general discussions). IMO, the lack of realizing this is reflected in comments like this:

SteveM and Willis were perceived has hardcore statistical skeptics, assuming that all analyses done be climate people are suspect.

Once you’ve gone through in any detail MBH98 (and related work), you would be nuts not to develope the attitude described above.

Since especially Student#2 (S2) seems to have sufficient understanding of statistics, I’d like ask him/her to do the following: please review/replicate (a part of) MBH98 yourself. Especially I have one specific task in my mind:

Replicate Figure 18 of Mann et al, Global Temperature Patterns in Past Centuries: An Interactive Presentation, Earth Interactions, 4-4, 1-29,2000. Once that is done it is easy to experiment with different window lenghts and lags (do it especially with 100 year window and lags 0,5,10). Try also with “standard correlations”. Then I’d like to know S2’s opinion on
a) how well the procedure was described in the papers
b) statistical maturity of the approach
c) what the choice of the method and the illustrated window lenghts (and lags) tell about the author(s) (read especially the text in MBH98)
d) how much trust we can put on this attribution study (see also what IPCC TAR says about the analysis)

Finally, I’d like to comment:

The climateauditors do not seem to understand parameteric vs nonparametric tests.
…
The climateauditors show a general lack of physical interpretation and a lack of appreciation of the fundamentally Bayesian approach

I think these are unfair generalizations. Some of us have Ph.Ds in these statistical issues. Some of us have Ph.Ds is related physics. And what comes to the appreciation of the Bayesian approach, I can not comment the attitudes of others, but personally I could have a long discussion with S2 about the matter … but for now I only refer him/her here.

bender

#219 was the last material post here; after that discussion drifted to “GT report card”

bender

Indeed, a histogram of annual hurricane count suggests a lognormal distribution. Formal tests of distribution fit to come.

David Smith

Here are the PDIs:

2002: 6.35 (from Emanuel)
2003: 22.6 (from Emanuel)
2004: 30.2 (from Emanuel)
2005: 23.2 (calculated by DRS (me))
2006: 7.9 (projected by DRS)

Frankly, I expected 2005 to be higher, given the monster storms that struck the Gulf Coast. But, several of those were rather short-lived.

Also, 2005 included at least four “trash storms” which were of minimal tropical storm strength and lasted only a day or two. In earlier times, these may have passed for nothing more than squally weather.

Steve McIntyre

I think that Willis posted up a data summary. Can you direct me to the posts. I’ll make a page with data links so that we can find them in this sprawling blog.

bender

Re #250
Do you have the HadISSTs for those years as well?
2002 28.01
2003 28.62
…

David Smith

Re #252 Willis posted the PDI numbers in the thread, “Bender on Hurricane Counts Continued”, post #19.

Re #253. Certainly. I’ll do that this evening.

Re #255. If the region is Emanuel’s SST box, it is 6N to 18N and 20W to 90W

bender

PDI is not as “wild” or “ill-behaved” as hurricane count.

Steve McIntyre

#259. It’s going to be an amusing replication. It will be fun to see why Science rejects it.

bender

The pinning effect is quite significant given the huge difference between active 2005 and inactive 2006. Pinning with active 2005 as the endpoint makes the 1949+ trend significant with p lt 0.1. With 2006 as the endpoint p goes up to 0.2. So that’s a pretty major change for a single datum. (Notably, if you do the smoothing properly, with lopping off of endpoints, then the regression is much more stable.)

Emanuel’s analysis started in the 1970s, however, not 1949. So that’s another thing to check. His trend is much more significant than just p lt 0.1. We’ll see next if the 2006 data with improper pinning effect is enough to push p over the insignificance threshold.

bender

LOL

bender

No problem. Thanks for double-checking.

David Smith

One of those nights – now, the link button won’t work for me.

Anyway, here’s the address of an interesting-looking paper on PDI and global temperature

http://www.uwm.edu/~aatsonis/High%20frequency%20variability%20in%20hurricane%20power%20dissipation%20and%20its%20relationto%20global%20temperature.pdf#search=%22power%20dissipation%20index%202005%22

It attributes to ENSO a major role in PDI variability, which was clearly shown on the correlation map someone (bender or willis) generated last week.

By the way, that correlation map also showed (in my opinion) a strong PDI correlation with upwelling in part of the Southern Ocean, which is a signal of a strong thermohaline circulation, which matches the classical idea of a strong Atlantic thermohaline circulation leading to an upturn in Atlantic storms.

bender

Re #267
1974+ analysis done.

When you cherry-pick your starting point as 1974 then there is such a pro-trend bias that the inactive 2006 season hardly influences the trend statistics.

So that’s it for sensitivity analysis. Now it’s time to move onto to attribution using Creighton’s filters.

David Smith

bender, I’ll be glad to do reading and offer thoughts on the physical processes behind the numbers. I hope Judith decides to participate with you guys.

Perhaps ironically, I’ll be spending most of today answering questions from auditors and helping them understand how we do things! These are safety auditors. Once a year we invite safety professionals from other locations to come in and look for things we’ve missed. It is rigorous and highly-detailed, and we answer a lot of questions that lead to nothing, but at the end of the day the audit process makes us a safer place.

bender

Re #273
Great – I was a little worried.

Willis, this Landsea windspeed “correction” – is that the same correction that is the difference between “OrigPDI” and “AdjPDI”? (If so, then it is absolutely miniscule.)

To help refocus I want us to recall exactly what the question was that was asked of us: “has PDI really doubled in recent decades?”

Chew on that question. Meanwhile, Steve M is working on getting my R script turnkey ready for posting. Anyone wihtout R should download it, and be sure to get the “Kendall” package as well. (Although M-K can’t help you answer parametric questions such as the one asked of us.)

Roger Pielke Jr.

Re: #273

If you look at Emanuel’s reply to Landsea in Nature he says (linked below):

“In correcting for biases in the original
Atlantic tropical-cyclone data, I relied on a
bias correction applied by Landsea, presented
as a table. I had fitted a polynomial to that
correction, as I felt that a continuous rather
than discrete correction was more defensible.
Landsea believes that this had the effect of
overcorrecting the most intense storms in the
pre-1970 record, and I accept his revision to
my analysis.”

However, in subsequent disucssions with Kerry and Chris it was clear that Kerry’s “acceptance” was ambiguous as there are in fact three curves:

A) Original
B) 1993 Bias adjustment
C) Emanuel’s polynomial

My undersatnding is that Kerry agreed to accept (B) but Landsea wanted (A). See Figure 1b here:

Click to access resource-1890-2005.48.pdf

So I’d agree with Judy and suggest that you use A and B if you’d like to bound Emanuel and Landsea, and include C if you want to go beyond this.

Judith Curry

A key issue in whether or not PDI has doubled in recent decades is the pre 1970 correction.
If someone can tell me how to upload a figure to this site i can illustrate. but i can give you the punchline (based upon my naive statistical analysis):

A comparison of the average from the previous active period 1944-1964 with the average 1995-2006 for the NATL only, PDI is 63% greater in the latter period with the correction, and 31% greater using uncorrected. So its a factor of 2 difference. i am not going to defend this statistical analysis here, i am expecting you guys to do all this correctly, i only include these rudimentary stats to show you that this issue does make a pretty big difference.

jae

Bender, Judy, Willis, et. al. If you pull this off, you will prove that science CAN be done on a blog.

David Smith

A big question is, how reliable is the historical storm data?

I took a sampling of the number of central pressure “observations” for the Atlantic storms of 1930, 1940, 1950, 1960, 1970, 1980, 1990 and 2000. The central pressure is important because it correlates well with wind speed. The number of observations is important because it tells us how often the storm was sampled (by aircraft, satellite, ship or land station).

If there is little or no sampling of a storm, then the reliability of the data is low, in my opinion. We rely on best-guesses, rather than knowledge.

Here are the number of central pressure observations per storm (be sure to see my caveats below):

1930: 0.5 observations per storm
1940: 0.5
1950: 0.15
1960: 4.15
1970: 9.0
1980: 20.6
1990: 24.6
2000: 25.7

Now, what this tells me is that, before 1960, we basically have a lot of best-guesses (WAGs in some cases) about intensities.

This is for the Atlantic, where the best historical records exist. Global historical records are probably even more problematic.

Caveats:
* The data shown is simply a sample taken every ten years. It is better to have done it annually (but that takes more time than I have currently).
* I used the Unisys database, as it is user-friendly and quick. It should match perfectly to the NHC database, but maybe it does not. It is better to have used the NHC database just in case.
* It would be better to calculate observations per storm-day, or per hurricane-day, so as to remove the effect of some seasons having longer-lived storms.

David Smith

Test test (I’m having trouble with the link button)

Judith Curry

Re the Klotzbach paper (mentioned on roadmap), here is an abridged version of my comments that i posted previously on the tropical listserv. I respond in *** to specific talking points on the Klotzbach paper that were posted on Gray’s website

If the increases in TC activity found by Emanuel [2005] over the past 30
years (based on data from 1975-2004) and Webster et al. [2005] over the past 35
years (based on data from 1970-2004) are robust, one would expect to see similar
trends over the shorter time span evaluated in this paper (1986-2005),
especially since SST increases have accelerated in the past twenty years.

*****This is flawed logic, fallacy of distribution of the divisional type,
whereby you cannot assume that what is true of the class is true of its members.
You cannot dice up the 35 year period and expect the same statistical
relationships to be present in each segment. 35 years is marginally short to
identify a statistically significant trend (people who criticized our study
because the length of the data record is too short raised a legitimate point).
20 years is definitely too short. The reason for this is that both the atlantic
and pacific have large multidecadal modes. if you pick a period that is too
short, what you are seeing is one piece of the mode. The Pacific has a big
multidecadal mode that peaked around 1990, so most of the data outside the N.
Atlantic is biased by this particular sampling.

There is considerable disagreement about the data quality before the
middle 1980s. Best track datasets for the Western North Pacific, the North
Indian Ocean and the Southern Hemisphere before 1985 should be “used with great
caution” according to the authors of the best track dataset.

*****No rigorous uncertainty analysis has been conducted to date. the data in the western North Pacific, which has 40% of global hurricanes/ typhoons, actually DECREASES in quality after 1987, when aircraft reconnaissance flights were discontinued in this region. so the arguments about choosing only the data since 1985 owing to better data quality is substantially flawed

With regards to ACE, there has been a large increase in ACE in the North
Atlantic basin since 1986. There has been a large decrease in ACE in the
Northeast Pacific basin since 1986. All other basins show small upward or
downward trends. Globally, there has been a slight increasing trend from
1986-2005; however, if only the past sixteen years are evaluated (1990-2005),
there has actually been a slight decreasing trend.

****the ACE confounds the number of hurricanes with the intensity (ACE
effectively includes both). There are several ocean basins where the number of
cyclones is actually decreasing, which would lead to a decrease in ACE (while at
the same time showing an increase in intensity). See also #1, re problems of
just looking at a 20 yr time period.

With regards to the number of Category 4-5 hurricanes, there has been a
large increase in North Atlantic storms but also a large decrease in Northeast
Pacific storms. When these two regions are summed together, there has been
virtually no increase in Category 4-5 hurricanes (i.e., 47 Cat. 4-5 hurricanes
from 1986-1995 and 48 Cat. 4-5 hurricanes from 1996-2005). For the globe, there
has been an approximate 10% increase in Category 4-5 storms from 1986-1995 to
1996-2005; however, most of this increase occurred from the late 1980s to the
early part of the 1990s in the Southern Hemisphere where some data quality
issues may have still been present. There has been very little change in the
number of Category 4-5 hurricanes since 1990, which is an agreement with Figure
4, panel A from Webster et al. [2005].

***** The more relevant metric would the percentage of cat 4-5 hurricanes (which
is what Webster et al. focused on). If the total number of hurricanes is
decreasing outside the N. Atlantic, then you would expect some decrease in Cat
4-5. The fact that you still get an increase in cat 4-5 hurricanes implies a
substantial increase in the % of Cat 4-5. See also #1, re problems in looking
at just a 20 year time period.

Thereis a positive correlation (significant at the 99% level) between SSTs and ACE values and Category 4-5 hurricanes for both the Atlantic and the Northeast Pacific basins. However, correlations between SSTs and ACE values and Category 4-5 hurricanes for all other basins (i.e., Northwest Pacific, North Indian, South Indian and South Pacific) are not significant.

****This argument was debunked by the Hoyos et al. paper recently published in
science. While other factors such as wind shear etc are important determinants
of the intensity of individual storms and even for seasonal average intensity
(owing to factors such as El Nino), there is no trend in wind shear, humidity,
etc. The analysis of Hoyos et al. clearly shows that the global increase in
intensity shares information with the global trend in tropical sea surface
temperature (and not wind shear, etc.)

TCO

Does the tropical listserv actually have good science discussion? The dendro listserv seems very weak. Mostly questions about what diameter borer to use. No in depth discussion of stats or even of competing physical mechanisms. This site much better then the dendro listserv.

David Smith

One more commentary on the poor quality of storm data:

An important question is, how accurate is the storm count in the early years?

Weak storms get named and count as part of the storm count, just as much as a superhurricane. They can be hard to spot, though, as the gale winds of tropical storms often cover small areas, maybe only 30 to 100 miles wide.

Prior to 1900, we had no satellites and aircraft, nor an organized weather monitoring and recording system, nor modern instruments, nor many settlers along some coastlines, nor many (compared to today) ocean-going ships in the deep tropics. Detection, measurement and record-keeping were full of problems.

Below are some plots of named storms from the 2000s, simply for a visual impression. These systems were so weak, and many had such short lives, that even giving them a name probably took some debate. Nevertheless, they count as part of the storm tally in the 2000s.

In looking at these, blue means winds of 35mph or less and green means the wind was above 35mph. So, the part of their track which rises to “storm” classification is the green part.

In my opinion, these named storms from the 21’st century would almost certainly have been missed in the 19’th century.

Bret,2005

Gert,2005

Jose,2005

Lee, 2005

Earl, 2004

Mindy, 2003

Peter, 2003

Fay,2002

Josephine, 2002

Jerry,2001

Lorenzo, 2001

Beryl,2000

Chris,2000

Ernesto,2000

One of the good things about using ACE or PDI is that these storms carry little weight. Emanuel/Mann use storm count back to the 1870s in their 2006 paper (see Figure 2), and compare it to modern counts, but comparing the two is apples-to-oranges.

David Smith

Re #290 Looks like the links don’t work, sorry, but the storm names are listed. The spam filter has been gobbling my posts (hmmm, maybe too many of them).

Judith Curry

#293 Thanks Willis, this analysis is very helpful. Elsner’s hypothesis is that by using a Granger Causality test he can show whether Atlantic SSTs are driven by global changes. I have trouble imagining a physical mechanism that says the global air temperature warms up and then the Atlantic follows, especially since the Atlantic is included in the global average. I inferred that this result was of some statistical interest, but was not associated with any kind of viable physical mechanism. Now you are stating that the statistics are dubious. This reinforces that the both physically and statistically viable explanations are needed; if you have one without the other, the one that you think you have is probably suspect.

bender

Good news for bender: Elsner’s a *serious* statistics wonk

That’s part of the problem in climate science – you don’t want “wonks”, you want statisticians. There are too many wonks. Bloom doesn’t take me seriously, but that’s not surprising; he is an uncertainty denier. There’s a lot of that going around.