There’s a guest post on Watts Up With That (WUWT) about a compilation of lower climate sensitivities plus a new one. It’s written by Patrick J Michaels and Paul Knappenberger, the Director and Assistant Director of the Cato Institute. The basic gist of the article seems to be that there is increasing evidence that climate sensitivity is lower than previously thought and probably close to about 1.5oC.
Their view on climate sensitivity seems to be based on the figure below (credit : Michaels & Knappenberger, WUWT) which shows the range of climate sensitivities determined by various different studies. There clearly are a number of studies that extend down to 1oC, but many also go up above 3oC. What seems fairly clear is that almost all cover the range from 2 to 3oC. I’m a little surprised that they think that this figure illustrates that climate sensitivity is probably around 1.5oC. It is clearly possible, but I would suggest that – based on this figure – one would probably conclude that it is most likely between 2 and 3oC.
What I found most interesting about this WUWT post was the final paragraph which says
We, at Cato’s Center for the Study of Science, will continue our efforts to portray the evolving state of climate science and to convince the powers-that-be that national and international assessments upon which EPA regulations are founded (and loony proposals for a carbon tax are based) are fatally flawed. Or as we put it, in our recent (April 12) review of the USGCRP’s draft “National Assessment,” in its current form, “the NCA [National Climate Assessment] will be obsolete on the day of its official release.”
This doesn’t sound, to me, like people who are objectively considering the scientific evidence. This sounds, to me, like people who have already made up their minds and are unlikely to change their minds whatever evidence is presented to them. I find it somewhat amusing (in a slightly depressing way) that climate skeptics can accuse climate scientists of being biased and of producing results that suit their ideology and then write – without any sense of irony – paragraphs like that above. Can’t they see that this makes them seem as though they are the ones that are biased and who are using evidence selectively so as to suit their ideology.
I must add, however, that I accept that climate sensitivity may well be lower than many current studies suggest. Maybe it is 1.5oC. Even so, that is still worrying since (as I suggested in an earlier post) this could still lead to significant warming within the next few hundred years. It would, however, require higher CO2 levels than would be required if climate sensitivity is between 2 and 3oC. This reminded me of one of the most convincing skeptical climate science talks that I’ve seen. The presenter was showing that historically countries (and companies) tend to overestimate their fossil fuel reserve and that these estimates tend to be revised downwards with time. He was therefore arguing that we didn’t have to worry too much about climate change since we would start to run out of fossil fuels by the middle of the 21st century. If climate sensitivity is low, then maybe this means that we don’t have to worry. We’ll start running out of fossil fuels before CO2 levels become high enough for significant increases in temperature. However, if we are likely to run out of fossil fuels within few decades, surely we should be investing in the development of new energy technologies now anyway. If we aren’t likely to run out of fossil fuels anytime soon, then even a reasonably low climate sensitivity is something to be concerned about and, again, shouldn’t we be considering alternative energy sources. In either case, it seems to make sense – to me at least – that we should start investing in alternative technologies. This also ignores all the other possible benefits of such an investment, such as energy security and economic growth through investing in your own economy, rather than buying energy from another country.