Just look at the population figures for the areas of the globe that are projected to become uninhabitable. That's your baseline number and it by itself is over

Just look at the population figures for the areas of the globe that are projected to become uninhabitable. That's your baseline number and it by itself is over a billion people. Any additional extrapolation for political and social upheavals related to resource conflicts (regardless of how conservative your analysis might be) only add to that baseline.