Attribution wars

We're going through another outbreak of the Attribution Wars, with a BBC report of a draft IPPC report that apparently seems to take a cautious approach to attribution of recent extreme weather to AGW.   The Guardian, on the other hand, looks at the glass half empty side of the report, for a completely different take.

As for new papers on the issue, James Hansen has a new "manuscript" out which deals with statistical increases in extreme heat.  John Neilson-Gammon thinks it does not always put things in the best way, and refers to his own analysis of the recent Texas heat wave and drought that (more or less) argued that climate change made a severe drought that would have come anyway extraordinarily severe.

But the Hansen paper contains a clear statement in support of a hunch I expressed quite a while ago - that the extreme weather attribution statements coming out of NOAA over the last year or two seemed to be leaping too quickly into a "no connection with AGW" conclusion.  As Hansen writes:

People who deny the global warming cause of these extreme events usually offer instead a meteorological "explanation". For example, it is said that the Moscow heat wave was caused by an atmospheric "blocking" situation, or the Texas heat wave was caused by La Nina ocean temperature patterns. Of course the locations of the extreme anomalies in any given season are determined by the specific weather patterns. However, blocking patterns and La Ninas have always been common, yet the large areas of extreme warming have come into existence only with large global warming. Today's extreme anomalies occur because of simultaneous contributions of specific weather patterns and global warming. For example, places experiencing an extended period of high atmospheric pressure will tend to develop drought conditions that are amplified by the ubiquitous warming effect of elevated greenhouse gas amounts

One other paper that I have not seen noted anywhere much on the internet or media.  A study noted at AGW Observer blog concludes this about the Australian recent drought:

In the context of the rainfall estimates introduced here, there is a 97.1% probability that the decadal rainfall anomaly recorded during the 1998–2008 ‘Big Dry’ is the worst experienced since the first European settlement of Australia.

That seems a pretty significant finding.

On the attribution issue generally, I still think that Michael Tobis' "black swan" argument is pretty convincing.