My friend Seth, whom I know from Berkeley (we taught a course together on left-handedness), has a blog on topics ranging from thoughtful discussions of scientific evidence, to experiences with his unconventional weight-loss scheme, offbeat self-experimentation, and advocacy of fringe scientific theories, leavened with occasional dollops of cynicism and political extremism. I agree with Seth on some things but not others. (Here’s Seth’s reason for not attempting a clinical trial of his diet.)
Recently I was disturbed (but, I’m sorry to say, not surprised) to see Seth post the following:
Predictions of climate models versus reality. I [Seth] have only seen careful prediction-vs-reality comparisons made by AGW [anthropogenic global warming] skeptics. Those who believe humans are dangerously warming the planet appear to be silent on this subject.
In response, Phil commented:
Funny, on the day you [Seth] made your post saying that you haven’t seen comparisons between models and predictions except by skeptics, the top entry on RealClimate, the single most prominent global-warming-related blog that is not run by skeptics, was “Evaluating a 1981 temperature projection.”
Pretty amazing, huh? On its face it would seem surprising to claim that the majority of leading climate scientists don’t do “careful prediction-vs-reality comparisons,” and indeed on the very day of Seth’s post, there is such a comparison right there on the first place you might look for what the climate scientists are doing!
How did Seth miss it?
A clue comes from the sources on which Seth relies. His link above points to the webpage of the Von Mises Institute, a political advocacy organization. Other Seth links to global warming stories have come from an climate change skeptic blog, a right-leaning politics blog, another climate change skeptic blog, another advocacy organization, one more climate change skeptic blog, a letter to the Wall Street Journal, yet another climate change skeptic blog, an op-ed in Forbes magazine, a lecture by science writer and political activist Matt Ridley, another blog that seems to specialize in climate change skepticism, conservative political columnist Jeff Jacoby, a Wall Street Journal op-ed, still one more climate change skeptic blog, a conservative religious magazine, . . . ummm, you get the idea.
If these are your sources, you can get a distorted view of the opinions and arguments of “those who believe humans are dangerously warming the planet”! Any one or two or three of the above sources might be informative, but it doesn’t make sense to only look there. (Quick: glance again at the list of sources in the above paragraph.)
I’m not saying that Seth has any sort of duty to read the scientific literature—he’s trained as a psychologist, not as a physicist—nor does he need to read RealClimate (even if only as a supplement to the Von Mises Institute page, Wall Street journal op-eds, and so on), but it seems pretty silly for him to be so sure of himself on the science, given that his selection of politically-loaded sources.
I’m not an expert on climate science either (I’m currently involved in a research project using tree-ring data to estimate historical climate, but my expertise in this project is in the statistics, not the biology or physics), so I asked Phil what his thoughts were on the particular article that Seth linked to (by David M. W. Evans, described as “a mathematician and engineer, with six university degrees including a PhD from Stanford University in electrical engineering”).
If you look at http://en.wikipedia.org/wiki/File:Satellite_Temperatures.png the temperature anomaly was higher in 1988 than in any other year until 1997…and was lower in the past couple of years than at most times in the past decade. The paper Seth blogged about looks at the change in temperatures since 1988 and says hey, there hasn’t been any increase whereas this modeler guy said the temperature would be way higher by now. If he had chosen 1985 or 1989 as the starting point instead, it would look different. Of course he’d say he chose 1988 because that’s when Hansen testified in Congress, so fair enough in a way…but this is a bit like the housing data that you blogged about, why not show the earlier data too? And the reason is the same as in the housing data: it’s because if you show the earlier data it undermines the story you are trying to tell. 1988 was an unusually hot year, by a lot.
Phil then turns to the RealClimate post (by Geert Jan van Oldenborgh and Rein Haarsma) mentioned earlier:
They compare a forecast from 1981 to data. This uses a land-ocean index rather than tropospheric temperatures…perhaps that’s an example of this guy cherry-picking too (the land-ocean temperature increase has been more rapid than the satellite-derived tropospheric temperature increase for reasons someone else might know but I don’t). Anyway this one shows a totally different story of course. Actually this guy cheats a little by starting his baseline too high I think, though that’s just based on a visual impression.
One thing that people who do these things don’t seem to understand is that the uncertainties in climate models (like low/medium/high curves) are supposed to represent the uncertainty in the trend, not the uncertainty for an individual year. It’s sort of like showing uncertainties in a regression model with one of those bow-tie curves: that doesn’t mean that you’re predicting that the individual data points will fall within the upper and lower curve, it means that the true line is probably somewhere in there. Similarly, people say “the past five years (or whatever) have been below the predicted trend line so the trend line must be too high,” apparently not realizing (or deliberately ignoring) that there is a lot of year-to-year variation, plus autocorrelation on the scale of a decade or so. It’s a true statement that global mean temperature was as high in 1988 as it was last year; it’s false to say that there’s not an upward trend in temperatures.
I think, though, that if Seth continues to search for information from his usual sources, he will remain convinced that there is no man-made global warming and that vast majority of scientists who study these problems are not interested in checking their models, have not ever thought about the ice age, etc etc.
I think this is important not only for the followers of Seth Roberts but more generally in that it illustrates the traps that people can fall into when seeking out confirmation of their beliefs. Seth is better-equipped than most people to read about scientific evidence, yet he is stuck, not only in holding a scientific view which I find implausible (after all, I might be wrong) but in not understanding that Geert Jan van Oldenborgh, Rein Haarsma, etc etc etc are doing serious science. It’s sad, and it’s scary.
P.S. Phil provides a good summary in this comment.