Scientific American posted a follow on story about long term drought forecasts in the Southwest U.S. and other areas. They argue that "a new analysis using a standard drought index augurs that by the end of the century devastating drought conditions will take hold over much of the populated areas of the world."
Whether this is from anthropogenic climate change or natural variabilities is still under study. [right, Lake Mead. Credit, National Park Service]
The authors of the study posit that human influence on the climate is still small relative to the natural changes over the past 50 years, although they note that human induced changes are expected to become much more significant.