Global warming is going to lead to winners as well as losers. I like this map as it shows how it is likely to break down for Africa. Gabon and Equatorial Guinea you win. Ivory Coast and southern Sudan you lose. Overall though, the impact on Africa is likely to be bad.
More important than global warming on Africa's well being is population growth.
Since 1970, population growth in sub-Saharan Africa has been faster than any other region in the world, placing even greater strains on food security and forcing farmers to intensify production beyond the point of environmental sustainability. This has resulted in large tracts of nutrient-depleted soil and the devastation of forested areas where soils are still productive. In addition, the projected effects of climate change have long-term implications for ecosystem and human well-being.via EarthTrends