by Judith Curry
Pat Michael’s testimony has been generating significant controversy, both in the hearing and in the blogosphere.
Michael’s Objective #2 relates to the attribution of climate change
Michaels concludes that:
Consequently EPA‘s core statement (as well as that of the IPCC and the CCSP), “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic GHG [greenhouse gas] concentrations”, is not supported.
My quick take on this is that I like the kind of approach he is using, as a complement to the model-based attribution of the IPCC. With regards to Michael’s specific analysis, since he introduced one anthropogenic factor (black carbon), he was obliged to use sulfates, also.
What we really need to do is look at the range of datasets of solar, sulfate, black carbon forcing, plus the multidecadal modes of natural internal variability.
On this thread, lets discuss the different observational forcing datasets for the period 1950-2010 in the context of the global average surface temperature anomalies and also the various statistical attribution studies. I will leave it to the commenters to introduce the relevant studies.