I was going to ignore the open letter-to-the-president advertisement placed in major papers recently by the Cato Institute. You’ve probably heard of it — the one that says Obama should ignore global warming alarmism because the science says it isn’t happening. The one signed by “over 100 scientists.” But the response elsewhere has been interesting. It focuses almost exclusively on the expertise of those who signed the letter, not the merits of the argument it makes. I find myself agreeing — ever so slightly, with the Cato Institutes’ Jerry Taylor, who defended the letter last week in the National Review Online. Only slightly, though, and only on the abstract notion of ad hominem logical fallacies.
First, let me just say that I disagree with Taylor that the president shouldn’t take the credentials of his advisers into account. In scientific endeavors, it would be foolish to pay more attention to laypeople than those who have devoted their professional lives to studying the subject. And I disagree with Taylor’s contention that it doesn’t matter how many experts you have arguing your side. Although it is a falsehood, as Taylor writes, that “that truth can be reliably determined by a show of hands. Nothing — especially in science — could be further from the truth” when the numbers are so lopsided against you, it is usually wise to at least consider why that’s the case.
But Taylor is correct, in principle, when he claims that “An argument’s merit has nothing to do with the motives of the arguer, the credentials of the arguer, or the popularity of the argument. Full stop. No exceptions.”
So let’s look instead at the scientific basis for the argument, which is laid out in the letter with the help of four footnotes backing up three claims.
1. Surface temperature changes over the past century have been episodic and modest and there has been no net global warming for over a decade now.
Supporting literature: Swanson, K.L., and A. A. Tsonis. Geophysical Research Letters, in press: DOI:10.1029/2008GL037022.
Brohan, P., et al. Journal of Geophysical Research, 2006. DOI:10.1029/2005JD006548
Here’s what Swanson and Tsonis actually conclude:
…we caution that the shifts described here are presumably superimposed upon a long term warming trend due to anthropogenic forcing…. If the role of internal variability in the climate system is as large as this analysis would seem to suggest, warming over the 21st century may well be larger than that predicted by the current generation of models, given the propensity of those models to underestimate climate internal variability.
and here’s what Brohan et al. say about the subject: Nothing. The paper is about uncertainties in 19th century data. But here’s what they do write:
Since the mid twentieth century the uncertainties in global and hemispheric mean temperatures are small, and the temperature increase greatly exceeds its uncertainty. In earlier periods the uncertainties are larger, but the temperature increase over the twentieth century is still significantly larger than its uncertainty.
So that does support the Cato letter’s contention that “there has been no net global warming for over a decade now.” No. Even if it did, (as Taylor likes to say), “so what? Ten years is not enough to come to any conclusions about long-term climate changes, as I explain in detail here.
2. After controlling for population growth and property values, there has been no increase in damages from severe weather-related events.
Supporting literature: Pielke, R. A. Jr., et al. Bulletin of the American Meteorological Society, 2005: DOI: 10.1175/BAMS-86-10-1481
This has become a contentious issue. Al Gore recently pulled a sequence of slides from his climate change presentation because of exactly this problem. But note what Pielke et al. include in their short article, which isn’t original research, just a reply to some:
Concern about the possibility of abrupt climate change, whether human caused or not, is well justified.
In other words, this is red herring. Just because we’ve been unable to see a signal of climate change in property damage trends is no reason to question the science behind anthropogenic global warming. Again, the authors are worried about what’s going on with the climate.
3. The computer models forecasting rapid temperature change abjectly fail to explain recent climate behavior.
Supporting literature: Douglass, D. H., et al. International Journal of Climatology, 2007: DOI: 10.1002/joc.1651. Which says:
Model results and observed temperature trends are in disagreement in most of the tropical troposphere, being separated by more than twice the uncertainty of the model mean.
Here we have a single paper that takes issue with an enormous volume of literature based on computer models that actually do explain recent climate behavior. It’s a paper about temperatures in the tropical troposphere, not the planet as a whole. Remember, we’re supposed to be examining “global” warming, not warming in Cost Rica and Ghana. The fact the some of the models fail to accurately predict what some parts of the atmosphere are experiencing does not invalidate AGW.
It turns out that climatologists have been remarkably accurate for decades now when it comes to anticipating global average temperature rise. There’s a nice piece in the New York Times of 1983 that shows how little the science has had to change despite a quarter century of observations.
So what does that leave the Cato Institute with? Not much. Zippo in fact. Just a list of more than 100 non-climatologists who think that several thousand climatologists are wrong, based on three research papers and one commentary that do absolutely nothing to undermine the consensus of the genuine experts.
And what does that tell you about those who signed on to the letter?