Five of eighteen climate system models participating the Coupled Model Intercomparison Project (CMIP) are chosen here for analysis based on their ability to simulate a reasonable present-day climatology of the Sahara Desert with similar rainfall distributions and meridional boundaries as in the observational data. When CO2 concentration is increased at one percent per year for 80 years in these models the Sahara moves north, becomes hotter and dries. Compared to the 40-year control run climatology, the mean average northward shift is around 0.55¿ latitude and the surface temperature is about 1.8¿C warmer at year 70 when the CO2 doubles. The local enhanced greenhouse effect from increased CO2 increases the net surface sensible heat flux, which in turn contributes to the warming trend.