The desert latitudes have shifted before, during the hotter 1930's when the
American midwest desertified, and around 1300, when the Anasazi ("cliff
dwellers") disappeared and the Aztec started migrating into central Mexico.
The
phenomenon has been well studied.
In Africa one aspect of the shift is to disrupt seasonal monsoons, so that
rains that normally go to Ethiopia and Somalia instead flood Mozambique, a
thousand miles or two to the south. Southeast Asian monsoons will also be
disrupted, with Indonesia particularly at risk.
Historically these warming/drying trends have been associated with major
population migrations and worldwide wars and invasions. Hopefully all this
will
blow over and we'll have nothing to worry about. Right?