AMS conference report: day 2

The convention center in New Orleans is impossibly overcrowded; the last time I saw lanes of people so thick was at the Ann Arbor Arts Fair many years ago. And I heard, from the Prob & Stat committee, that the AMS will likely choose to come to New Orleans more often in the future.

There were about two dozen sessions going on at any one time, meaning it is impossible to hear most talks (this is true of nearly any academic conference). I spent most of the day listening to technical statistics and probability talks that won’t be of much interest to you, and I missed some talks on climate change “impact”, which are always nothing but forecasts with no attempts at verification, and thus of little use.

But there were four talks that had some meat.

1. Kerry Emanuel spoke on a hurricane “downscaling” method his group at MIT developed. Most weather and climate models give results at the very large scale, they are computed at “grid points” over the earth’s surface, and these grid points can be very far apart. This means that phenomena that occur between those grid points are not modeled or not seen. But they can be estimated using statistical methods of downscaling. Emanuel’s method is to infer, or downscale, hurricanes from global climate models. He showed some results comparing their method with actual observations, which did well enough, except in the Pacific where it faired poorly.

The main point was to ask whether or not hurricane intensity would increase in the years 2180-2200, the time when CO2 is expected to be twice what it was in pre-industrial days. Intensity is measured by his “power dissipation index”, which is a function of wind speed: obviously, hurricanes that are windier are stronger. The gist was this PDI would increase only very slightly, because hurricane numbers themselves would increase only slightly, if at all.

But aren’t hurricanes supposed to spiral out of control in a warmer world? Not really. He gave a technical discussion of why not: broadly, some levels of the atmosphere are projected to dry, which, through various mechanisms, lead to fewer storms.

He gave no measure of the uncertainty of his results.

2. Tom Knutson asked “Have humans influenced hurricanes yet?” or words to that effect. He showed that Emanuel’s yearly summery of PDI correlates nicely with sea surface temperatures (SSTs): higher SSTs lead to higher PDIs. Well, kind of. Actually, the graph of his that people like to show are not the actual SSTs and PDIs but a “low-frequency filtered” version of SSTs and PDIs. There is an inherent and large danger in applying these kinds of filters: it is too easy to produce spurious correlations. Nobody mentioned this.

The obvious question to ask: why filter the data in the first place? The answer is that the signal is not there, or not there too obviously, in the raw data.? But people want to see the signal, so they go after it by other means.? And there are good physical reasons to expect that the signal should be there: all things being equal, warmer water leads to windier storms. But as I stress again and again: all things are rarely equal.

Knutson looked for an anthropogenic signal in hurricane number and did not find any and cautioned that we cannot yet tell whether man has influenced tropical storms. He gave no quantitative measure of the uncertainty in his results.

3. Johnny Chan looked at land-falling tropical storms in the West Pacific. He showed that there were large amounts of inter-decadal and inter-annual variations in typhoon numbers, but there was no increase in number. Again, no quantitative measure of uncertainty.

4. Chris Landsea showed some of his well-known results: before 1966 wide swaths of the North Atlantic were not accounted for in hurricane measurements. This is because before that time, there were no satellites; measurements then were serendipitous: if a ship traversing the ocean ran into a hurricane, it was noted, but, obviously, if no ship was there, the hurricane made no sound. Too, since 1966 changes in observation practice, in the instruments used to measure, and in the algorithms processing the raw data have led to a quantitative differences in the number and qualities of tropical storms. This basically means that, recently, we are able to see smaller, shorter-lived storms that went previously unnoticed.

Now, if you look at raw plots of storm number through time, it looks, sometimes, like these are increasing. But how much of this increase is real and how much do to increased observation power? Knutson and his group tried to answer that, but it’s difficult, and, of course, there will never be a way to be certain.

My talk, which I give this morning, echoes Landsea’s. I find that the variability of storm intensity has increased: this could be accounted for if more smaller storms are able to be observed.

The best thing is that all these scientists spoke just like you would think good scientists should: a lot of “maybes”, “conditional on this being right”, and “I could be wrongs” were heard. There was none of the apocalyptic language you hear in the press.

Prominent philosopher commits global warming fallacy

This post was supposed to be titled, “Conference Report: Day 1,” because I intended to give a blow-by-blow of the American Meteorological Society meeting which started yesterday here in New Orleans. But since I spent the day slowing dying in my hotel room, I have nothing I wish to report. I only missed the opening ceremonies, however. This is some loss, but not a big one; these introductory speeches usually have something worth teasing. Anyway, today I find I am still alive, and can go to the actual talks.

This one has been making its way around the net: original post. It is a story about the University of Amsterdam philosopher Marc Davidson who has written a peer-reviewed paper which claims that people who “deny” that global warming is catastrophic are just the same as those people who defended slavery! Yes: the full dull academic title of this pearl of an argument is “Parallels in reactionary argumentation in the US congressional debates on the abolition of slavery and the Kyoto Protocol.”

It seems that some U.S. Congressperson, about 200 years ago, said something stupid along the lines of “if we get rid of slavery, we will lose too much money.” The parallel that Davidson found, to his horror, is that some modern politicians are saying something like, “Punitive laws and tariffs to reduce CO2 may be unnecessarily costly and premature.” To Davidson, this only meant one thing: scientist-hating lynch mobs were just around the corner.

No, he didn’t actually say “lynch mobs”, but his hint is sufficiently strong.

My careful readers will have noticed, however, that Davidson, despite his prestigious academic pedigree, has committed the logical fallacy of the idiotic argument. This has an official Latin name, as all fallacies do–something like fatuus headus argumentum—but I can’t recall the exact phrase. Because, of course, to say that because some nincompoop once incorrectly applied an argument from economics, all future arguments based on economics imply sympathy with slavery.

Think about that the next time you clip coupons: just don’t say you are doing it to save money, because that is an economic argument.

National Post says statisticians needed too

Canada’s National Post, in a piece from a little more than a year ago, made a call for more statisticians to be involved in climate change research, much as the American Meteorological Society recently did. It’s relevant again, because the Post article is highlighted today on the indispensable

The title of the article is somewhat ridiculously called “The Deniers — Part I,” as if the only opposite course is to be devout and be a “Believer.” But let that pass. There are IX–excuse, me, 9—other parts to the series, highlighting topics like “warming has benefits” (true), “the sun moves climate change” (true), and “limited role for CO2” (also true). None of these are strictly “denialist” positions; they are, in fact, attempts to fully understand the physics of the climate system. To call those who study these areas “deniers” shows, then, how far we’ve slipped from sanity.

Anyway, Part I is more or less an interview with Ed Wegman, who is “professor at the Center for Computational Statistics at George Mason University, chair of the National Academy of Sciences’ Committee on Applied and Theoretical Statistics, and board member of the American Statistical Association.” Wegman was the guy who investigated Michael Mann’s “hockey stick” temperature curve and found the statistical methods behind its data analysis wanting.

Ed says that if “statistical methods are being used, then statisticians ought to be funded partners engaged in the research to insure as best we possibly can that the best quality science is being done, [and] there are a host of fundamental statistical questions that beg answers in understanding climate dynamics.”

One place to recruit these statisticians is from the American Meteorological Society’s Probability & Statistics Committee, but Ed is suspicious: “I believe it is amazing for a committee whose focus is on statistics and probability that of the nine members only two are also members of the American Statistical Association, the premier statistical association in the United States, and one of those is a recent PhD with an assistant-professor appointment in a medical school” (emphasis mine).

My readers, who are lovers of logic, will have instantly noticed that Ed has committed the “appealing to authority” fallacy when he implies that the poor schmuck stuck in the medical school cannot possibly know anything of climatology.

My friends, that schmuck is me. The other ASA member is Tilmann Gneiting, of the University of Washington, who is brilliant and one of the world’s biggest sweethearts. I can also set your minds at ease by telling you that the non-ASA members are no slouches at statistics, and they know a great deal of physics.

I wrote Ed to let him know that if he wanted to check my record, he might find that he and I are not too far apart. But Ed’s pretty busy and I’m still, at 1+ years, waiting for his response.

No, my point of writing this post was not just to stick it to Ed a little. It turns out the Post article and Wegman’s comments are topical, because starting tomorrow the AMS holds in annual meeting in New Orleans. The Probability & Statistics Committee will meet at this time, and also sponsor a four-day conference. I give my global “hurricanes have no increased” paper; Gneiting has a paper, and so do several other statisticians. I’ll be (trying to) write daily updates about major papers and so forth.

I’ll also let you know if I see Wegman haunting the halls.