Parts of Africa have the most rapid population growth in the world. Recent studies by climatologists suggest that, in coming decades, ecologically vulnerable areas of Africa, including the Sahel will be exposed to the harshest adverse effects of global warming. The threat hanging over parts of sub-Saharan Africa is extreme. Fortunately, there are evidence-based achievable policies which can greatly ameliorate what would otherwise be a slowly unfolding catastrophe of stunning magnitude. But to succeed such measures must be taken immediately and on a large scale.