The drying up of Lake Chad was used as an example of global warming. The judge said: "It is apparently considered to be more likely to result from ... population increase, over-grazing and regional climate variability"

THE TRANSCRIPT

Focus most of all on this part of Africa just on the edge of the Sahara. Unbelievable tragedies have been unfolding there and there are a lot reasons for it. Darfur and Niger are among those tragedies and one of the factors that has been compounding this is the lack of rainfall and the increasing drought. This is Lake Chad, once one of the largest lakes in the world. It has dried up over the last few decades to almost nothing. That has been complicating the other problems that they also have. The second reason why this is a paradox: Global warming creates more evaporation of the ocean to seed the clouds, but it sucks moisture out of the soil. Soil evaporation increases dramatically with higher temperatures. And that has consequences for us in the United States as well.

THE RULING

6. Lake Chad etc

The drying up of Lake Chad is used as a prime example of a catastrophic result of global warming. However, it is generally accepted that the evidence remains insufficient to establish such an attribution. It is apparently considered to be far more likely to result from other factors, such as population increase and over-grazing, and regional climate variability.

Gavin:

 

the sahel drought being attributable to aerosols is from the work of

Isaac Held (submitted/in press?) and Biasutti and Giannini (2006) (both

attached). You get a sahel drought at the right time (not quite the

magnitude) in the AR4 runs and individual forcings show that the anthro

aerosols are mostly to blame. This is on top of the well known result

that AMIP-style runs give you a sahel drought with no forcings (implying

the signal is carried predominantly in the SST).

 

mt:

          Again it isn't clear to me that the judge is watching the same film I saw...