James Hansen: Flip-flopper?

During our appearance last week on the local Pittsburgh Cable News Channel (PCNC) television show NightTalk, host Mike Pintek came out swinging. While introducing me, he said, “Dr. Mitchell is going to talk about global warming, and I have a feeling he and I are going to fight a little bit about that.”

As the bell for round one sounded, I braced myself for a barrage of global warming skepticism from the frisky host. But Pintek’s fusillade never came, and viewers never got to see his best punch. After the show, Pintek opened a manila folder and eagerly showed me several pages of densely highlighted internet print-outs. This was his global warming fight plan, with the lead argument being an attack on the credibility of NASA climate scientist James Hansen.

Pintek accused Hansen of being a flip-flopper, having forecast an ice age back in the 1970s, and now projecting catastrophic warming. The origin of this popular meme can be traced to a September 19, 2007 Washington Times article, in which John McCaslin dangles an interesting tidbit – that in his 1971 research on climate cooling, scientist S.I. Rasool used “a new computer program developed by Mr. Hansen that studied clouds above Venus.”What was this program? As Hansen explained recently:

It was a ‘Mie scattering’ code I had written to calculate light scattering by spherical particles. Indeed, it was useful for Venus studies, as it helped determine the size and refractive index of the particles in the clouds that veil the surface of Venus. I was glad to let Rasool and Schneider use that program to calculate scattering by aerosols. But Mie scattering functions, although more complex, are like sine and cosine mathematical functions, simply a useful tool for many problems. Allowing this scattering function to be used by other people does not in any way make me responsible for a climate theory.

In other words, Hansen is not responsible for the 1971 Rasool/Schneider findings on global cooling. Forcing the link is like blaming Henry Cavendish, discoverer of hydrogen, for the crash of the Hindenburg.

Yet this fact has not stopped journalists from picking up the Hansen attack meme and running with it. KUTV, the CBS Salt Lake City affiliate, goes with the headline: “Global Warming Scientist Once Warned of ‘Ice Age’.” In the story, reporter Doug Ware asserts: “But 36 years ago, it appears, Hansen had a completely different warning – in what may be the scientific equivalent of a grandiose political ‘flip-flop’.” The Investor’s Business Daily, Rush Limbaugh, and NewsBusters also uncritically plug the meme.