And they will. I think the current migration crisis in Europe is nothing compared to when the Sahel will be finally total uninhabitable all those people will move to Europe. And with the current speed of the global warming I don't think it's that far away.
This seems inevitable at this point. Africa is headed for a population crisis. Places like Somalia and Niger have around 6 or 7 children per woman. These are countries that already import a lot of food to feed rapidly growing populations. If we have another energy shock, it's unclear to me who is going to feed all of these babies.
Edit: right after writing this the very next HN article I come across is massive locust swarms threatening crops in Africa. Scary