A couple of years ago, I had a guest post about Pat Frank’s suggestion that the propagation of errors invalidate climate model projections.. The guest post was mainy highlighting a very nice video that Patrick Brown had produced so as to explain the problems with Pat Frank’s suggestion. You can watch the video in my post, or on Patrick Brown’s post.
Pat Frank has, after many rejections, managed to get his paper published. If you want to understand the problems with this paper, I suggest you watch Patrick Brown’s video, and read the comments on my post and on Patrick’s post. Nick Stokes also has a new post about this that is also worth reading.
However, I’ll briefly summarise what I think is the key problem with the paper. Pat Frank argues that there is an uncertainty in the cloud forcing that should be propagated through the calculation and which then leads to a very large, and continually growing, uncertainty in future temperature projections. The problem, though, is that this is essentially a base state error, not a response error. This error essentially means that we can’t accurately determine the base state; there is a range of base states that would be consistent with our knowledge of the conditions that lead to this state. However, this range doesn’t grow with time because of these base state errors.
As Gavin Schmidt pointed out when this idea first surfaced in 2008, it’s like assuming that if a clock is off by about a minute today, that tomorrow it will be off by two minutes, and in a year off by 365 minutes. In reality, the errors over a long time are completely unconnected with the offset today.
Maybe the most surprising thing about the publication of this paper is that the reviewers (who are named) both seem to be quite reasonable choices. It seems highly unlikely that they missed the obvious issues with this paper. Did it get published despite their criticisms? Did they eventually just give up and decide it wasn’t worth arguing anymore? Or, did someone decide that this was something that should play out in the literature? I think the latter can sometimes be a reasonable outcome, but only if the paper has something that’s actually interesting, even if it is wrong. Pat Frank’s paper really doesn’t qualify; it’s simply wrong, and not even in an interesting way.