I think certainly it is a factor. I've been following the steady northward advance of the Sahel since before the notion of human caused global warming was prevalent. Historically, northern Africa grew grain in abundance, supporting the Empire of Carthage starting in 800 BC. Ethiopia and Somalia were abundant producers of grain for wide export. The Sahara had been drier than today during the last glaciation but became wet from about 9000 to about 5500 years ago, when desert spread across Egypt and continued spreading. The expansion of the Sahel in all directions, but especially to the north and south, has accelerated in the twentieth century and continues to the present. Obviously the causes must be complex, but I don't think that expansion is coincidental to the warming of the planet.

What do you think? Do you think we'll see a reversal of this expansion soon?