Here's a 2013 study in Nature on the subject[1]. Drought has increased over many land areas since 1950, pretty well matching their model, which predicts increasingly severe drought over the next 30-90 years.
For much more on the subject, a great book is Six Degrees by Mark Lynas, who reviewed about 3000 papers on the projected effects of climate change (and referenced them extensively). I don't remember all the details, but one issue is that more heat brings more evaporation, drying out the soil. Rainfall tends to be less frequent and harder, which washes away the dried-out topsoil.
Another issue is that rain clouds tend to form over the warmer ocean, instead of drifting over land. Rain falling in the Indian Ocean is expected to cause severe drought in Africa (and that's already been seen to some extent).
For much more on the subject, a great book is Six Degrees by Mark Lynas, who reviewed about 3000 papers on the projected effects of climate change (and referenced them extensively). I don't remember all the details, but one issue is that more heat brings more evaporation, drying out the soil. Rainfall tends to be less frequent and harder, which washes away the dried-out topsoil.
Another issue is that rain clouds tend to form over the warmer ocean, instead of drifting over land. Rain falling in the Indian Ocean is expected to cause severe drought in Africa (and that's already been seen to some extent).
[1] http://www.nature.com/nclimate/journal/v3/n1/full/nclimate16...