On the likelihood of recent record warmth

Source: On the likelihood of recent record warmth

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:

1. Assume that the global surface temperature estimates are accurate; ignore the differences with the satellite atmospheric temperatures
2. Assume that the CMIP5 multi-model ensemble can be used to accurately portray probabilities
3. Assume that the CMIP5 models adequately simulate internal variability
4. Assume that external forcing data is sufficiently certain
5. 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.