March 04, 2007

Varieties of Denialists

Obnoxious. That's the word that comes to mind here. Via Chris Mooney, I see that the Senate Republican Policy Committee, chaired by Kay Bailey Hutchinson, has put out a new "paper" on global warming. They start off on a promising note, steering clear of outright global warming denial and admitting three basic truths:
1. Atmospheric concentrations of greenhouse gases have risen from 280 parts per million (ppm) to 380 ppm over the last century due in large part to fossil fuel consumption.

2. The Earth's average temperature has risen approximately 1.3 degrees F over the last century.

3. Carbon dioxide, methane, and a few other trace gases exert a warming influence on the climate.
So far, so good. But that's about as far as the paper gets before it starts with the obfuscation. For starters, there's this line: "[I]t is difficult to determine how much of the past warming is due to human activities." Well, no. The summary of the IPCC's fourth assessment report (AR4) is perfectly clear about this—stating with "very high confidence" that human activity has caused the bulk of this warming. Check out pages 4, 5, and 16.

There's also a lot of confusion over climate sensitivity. The IPCC's AR4 estimates that a doubling of carbon dioxide concentrations in the atmosphere will lead to a warming of anywhere from 2 to 4.5 degrees C—with a best guess of about 3 degrees. This estimate has much to do with the idea that water vapor acts as a feedback mechanism, enhancing the effect of warming caused by greenhouse gases. The only credible scientist who's really challenged this theory is MIT's Richard Lindzen, who has disputed the role that water vapor plays and has estimated that the climate sensitivity is actually only about 0.5 degrees. (That'd be good news if true.)

But his paper, written in 2001, has come under attack from on all sides, and is generally discredited. Lindzen has never produced a model to explain the current warming, and is more likely than not simply wrong. (Indeed, he appears to have edged away from his "iris" theory.) Nonetheless, the RPC paper leans heavily on Lindzen's work, and rather than admit that the guy's suffered severe criticism, they simply note that "these scientific debates illustrate the uncertainties that still exist." Ah, yes. It's just like the "debate" over intelligent design. They can't figure out who's right, so we should just "teach the controversy". What crap.

Reading through the RPC paper, they also manage to cite Chris Essex, a mathematician whose book on global warming, written with famed "skeptic" Ross McCritick, was riddled with errors. Nice! And in order to argue that there's a lot of uncertainty about climate models, they cite Hendrik Tennekes, who has not published anything in a peer-reviewed journal since 1990, and collaborates frequently with Dr. Fred Singer's "Science and Environmental Policy Project," a major denier group.

The whole thing's a clever bit of hackery. And to be honest, I find the RPC paper—which does make at least a half-hearted attempt to understand the science—far more infuriating than many of the outright deniers. I mean, sure, it seems that 87 percent of Republicans in Congress, along with a bunch of right-wing bloggers, refuse to believe that human activity is the primary cause of global warming. They're easy to deal with, though. We just call them idiots and ignore them entirely.

But the thing is, there really are legitimate debates about how to handle global warming. Even the folks at RealClimate will tell you that uncertainties exist over, for instance, many of the effects of climate change—how high the sea levels will rise, how many species will die off, what sorts of droughts or hurricanes we can expect. Moreover, there are debates to be had about what sorts of risks and costs are acceptable when formulating policy. Personally, I think the evidence strongly favors James Hansen's view that if the earth's temperature rises 1-2 degrees C above year-2000 levels, we're entering an era of unprecedented warming that carries extremely severe risks. A lot of scientists agree with that view, but it's not out of bounds to criticize it, or quibble over the details.

So the Republican Policy Committee could have just accepted the IPCC consensus and gone on to ask perfectly reasonable questions. Instead, they're merely conceding the bare minimum necessary to avoid getting laughed off the stage (i.e., "okay, global warming's happening and humans play some role"), and then kicking up a flurry of disinformation to confuse people. Hutchinson's oil patrons must be thrilled. There's no indication that these "sensible" Republicans really care about trying to understand the issue. The whole thing's a joke. Maybe "obnoxious" isn't the right word after all.
-- Brad Plumer 4:47 PM || ||