I’ve had some response to my earlier post about NASA scientist James Hansen suggesting I indulged in guilt-by-association. I was careful to entitle my post “If you’re into transparency.” Scientists skeptical of catastrophis anthropogenic global warmings are often attacked for their links to conservative/libertarian organizations or previous consultancies with fuel companies. I hope those that condemn guilt-by-association will apply that standard equally in future.

It is quite right that scientists should be judged on the quality of their science. Indeed, I have often praised how Dr Hansen has recognized the problems with IPCC models and produced his own alternative emissions scenarios that show much lower warming this century. His work on the role of black carbon (soot) in recent warming also demonstrates that greenhouse gases are not the only “culprit” in warming.

I am, however, concerned by the way Dr Hansen often allows himself to be portrayed as a policy advocate rather than scientist. As a former government employee myself, I knew that my role was incompatible with political activity, which is why I was not a member of the Conservative Party while I was so employed. Yet Dr. Hansen saw fit to endorse a candidate for the Presidency of the United States in a forum where his job as a government scientist was presumably the main draw for the audience. I cannot be alone in regarding that as inappropriate.

Dr Hansen publishes his scientific work all the time and I do not believe there has been any attempt to stop that process. Scientists should let their science do the talking. There are plenty of policy advocates to make the political arguments.