Judith Curry’s conclusions regarding the much publicized paper by Mann et al. in Nature:
As I see it, this paper is a giant exercise in circular reasoning:
- Assume that the global surface temperature estimates are accurate; ignore the differences with the satellite atmospheric temperatures
- Assume that the CMIP5 multi-model ensemble can be used to accurately portray probabilities
- Assume that the CMIP5 models adequately simulate internal variability
- Assume that external forcing data is sufficiently certain
- Assume that the climate models are correct in explaining essentially 100% of the recent warming from CO2
In order for Mann et al.’s analysis to work, you have to buy each of these 5 assumptions; each of these is questionable to varying degrees.