"bill" wrote
Granted, however, as the climate regime changes, the weather
patterns will change with them and places which have traditionally not
gotten rain will begin to. in the case of the sahara, the southerly
shifting of the gulfstream will start to drop rain there instead of
europe.

Warm moist air must still flow over the rockies to get to the U.S.
midwest, and in so doing lose it's water vapour content.



Bill wrote:
In addition, the melting of the polar caps, and the attendant rise
in sea levels will further increase the global precipitation since
evaporation is a surface phenomenon.

While there will be a significant reduction in coastal areas the ocean
surface area will not change substantively. Neither will the continental
landmass significantly be reduced. However since most major cities are
located on the coasts, most will suffer great destruction.