In a post at Klimazwiebel, Von Storch and Zorita have expanded onf the views they put forward in the discusion paper I mentioned the other day.

We want here to set straight some misinterpretations that may have arisen in the blogosphere, e.g. Bishophill, and may also have been present in the review processes by Nature as well.



The main result is that climate models run under realistic scenarios (for the recent past) have some difficulty in simulating the observed trends of the last 15 years, and that are not able to simulate a continuing trend of the observed magnitude for a total of 20 years or more. This main result does not imply that the anthropogenic greenhouse gases have not been the most important cause for the warming observed during the second half of the 20th century. That greenhouse gases have been responsible for, at least, part or even most of the observed warming, is not only based on the results of climate simulations, but can be derived from basic physical principles, and thus it is not really debated. It is important to stress that there is to date no realistic alternative explanation for the warming observed in the last 50 years. The effect of greenhouse gases is not only in the trend in global mean near-surface temperature, but has been also identified in the spatial pattern of the observed warming and in other variables, such as stratospheric temperature, sea-level pressure and others.

Although von Storch and Zorita talk of misinterpretations, I'm not sure there is any great difference between what they say here and what I concluded last week. At the time I said that the models are falsified - they run too hot. A model that had a slower rate of warming would not be. So a claim that part of the observed warming is anthropogenic is still scientifically tenable. How big a part is manmade is, given the failure of the models, anyone's guess.

I'm not, however, convinced that the only plausible explanation for the warming of the last 50 years is greenhouse gases. As I mentioned the other day, the IPCC looks set to conclude that there was a Medieval Warm Period. Last time I heard Rob Wilson discuss the matter, he said that the climate models couldn't even get the MWP in the right historical position, let alone explain its apparently large magnitude.

So once again I find myself returning to the point I make so often. The unknown unknowns are a big problem. Scientists would do themselves a favour if they recognised it.

[Comments will be tightly edited for relevance and tone]