Earlier quoted context omitted.
Desertification of previously farmed arable land is going to result in significant migrations and food supply instability. I think it goes without saying that will result in lost lives from myriad direct causes. This is the sort of thing wars are made of.
A lot more land will become arable, too. It might as well be a net plus, who knows. Africa already imports > 80% of its calories anyway.
[1] I say might, because there's uncertainty around this. I do know, with absolute certainty that redistributing - say - your organs to multiple people who need transplants would definitely be a 'net plus', but you don't see me making such bloodless utilitarian arguments.