Climate Science and Politics, but not IPCC

February 8th, 2005

Posted by: Roger Pielke, Jr.

I have received some comments asking whether or not I think that IPCC scientists should simply remain mute on issues of climate science or politics. The answer is “no” – in my view IPCC scientists should feel free to speak out as they see fit, but they should be careful when using the authority of the IPCC to establish their credentials. A good example of a scientist speaking out who did not rely on his IPCC credential appeared in The Washington Post on Sunday. The Post contained an article on recent drought in the western United States, including some very strong claims that it has been caused by greenhouse gas emissions to the atmosphere. Here is an excerpt:

“Jonathan Overpeck, who directs the university- and government-funded Institute for the Study of Planet Earth at the University of Arizona, said current drought and weather disruptions signal what is to come over the next century. Twenty-five years ago, he said, scientists produced computer models of the drought that Arizona is now experiencing. “It’s going to get warmer, we’re going to have more people, and we’re going to have more droughts more frequently and in harsher terms,” Overpeck said. “We should be at the forefront of demanding action on global warming because we’re at the forefront of the impacts of global warming. . . . In the West we’re seeing what’s happening now.””

The statements by Overpeck are quite similar to those made by Kevin Trenberth on hurricanes and discussed at length in the Prometheus archives. But there is one important difference. Like Trenberth, Overpeck is also a Coordinating Lead Author for the IPCC’s fourth assessment report, but Overpeck (or the Post) does not rely on this connection to establish his credentials. Hence, in this case there is no ambiguity about whether or not Overpeck is speaking for the IPCC or himself. I have no complaint on Overpeck making these assertions.

(For more on climate and drought in the U.S. Southwest see this report from Overpeck’s group at Arizona.)

One Response to “Climate Science and Politics, but not IPCC”

    1
  1. bubba Says:

    …while I’ll applaud Dr. Overpeck’s omission of his IPCC ties, I still find it somewhat startling that he is tieing the current drought, even indirectly, to global warming.

    A casual reader, unversed in the climatology of the desert southwest, after reading Overpeck’s comments in the WAPO article would easily come away with the impression that the current drought is somehow linked to global warming and this is the beginning of AGW climate change in Arizona (my girlfriend, a former resident of New Mexico, certainly did).

    Being familiar with Mantua’s research I kinda rolled my eyes and chalked it up to sloppy editing. Especially after following your link to Overpeck’s report from last year. It very clearly denotes that “(t)here is no persistent long-term upward or downward trend in precipitation during the last century.”

    So how can he now credibly infer “current drought and weather disruptions signal what is to come over the next century”?

    I should think a clarification is in order.