IPCC Report released September 27

The IPCC (Intergovernmental Panel on Climate Change) released its Summary for Policy Makers on September 27 as the first part of its fifth report on climate change called for short AR5. Its 4th report (AR4) was published in 2007. There is much commentary already by warriors on both sides in the "climate war." Two of the calmer commentators I like among academics are Judith Curry and Roger Pielke, Jr.

In Roger's post of today, he points out (among other things) that we can't know for certain what effect that efforts to curtail CO2 emissions will have until mid-century. That is true because the ranges of predicted earth temperatures for the best and worst cases overlap. Here are the numbers: In the best case (i.e., the most aggressive policy to curtail GHG (green house gases), the predicted temperature increase for 2046-2065 is 0.4 to 1.6 deg C (mean 1.0). For the least aggressive mitigation (i.e., no curtailment of GHG), it is 1.4 to 2.6 (mean 2.0). So, to the extent that we believe these predictions, it is possible that the increase in temperature could be 1.5 deg C regardless of what policy we follow.

Since the response to mitigation measures takes so long, it is silly to talk about short-term effects. He gives one example of such silliness in a quote by Al Gore of eight days ago:

Three years ago, Congress failed to put a price on carbon and, in doing so, allowed global warming pollution to continue unabated. We have seen the disturbing consequences that the climate crisis has to offer—from a drought that covered 60% of our nation to Superstorm Sandy which wreaked havoc and cost the taxpayers billions, from wildfires spreading across large areas of the American West to severe flooding in cities all across our country—we have seen what happens when we fail to act. 

Criticizing 'climate science'

I responded to an op-ed by Mark Buchanan in the San Diego Union-Tribune on 9/25 as follows:

Mark Buchanan puts up straw men in his article (“Uncertainty on climate is a sign of good science,” September 25), one an anonymous friend who claims that “global warming couldn’t possibly be caused by humans.” The other is skeptics who savaged the upcoming report, “as if trying to be accurate was an offense.” If these exist at all, they are certainly what some call “outliers” – i.e., very rare.

 

The IPCC report and the process through which it is produced is roundly criticized, however, for good reasons, the main one being that the IPCC has become so politicized as to be practically useless. A good summary of the problem was well expressed by Roger Pielke, Jr., this way: “A difficult question for the climate science community is, how is it that this broad community of researchers -- full of bright and thoughtful people -- allowed intolerant activists who make false claims to certainty to become the public face of the field?” I’m not accusing Mr. Buchanan of being one of the “intolerant activists,” but he might want to be careful about who associates with.