It looks like environmental scientists are not jumping into the Afro-optimist bandwagon. Marchiori, Maystadt, and Schumacher (2012) predict that climate change will force migratory flows from the coastal areas to the mainland in Africa, and East Africa will be particularly affected  (click on the image to enlarge).

Marchiori, Maystadt, and Schumacher (2012)

Marchiori, Maystadt, and Schumacher (2012)

Such a mapping gives an idea of the potential centripetal process induced by environmental migration. While there has been a long tradition of migration to the coastal agglomerations in Africa (Adepoju 2006), coastal areas could experience a significant proportion of their population fleeing toward African mainland due to climate change by 2099. In West Africa, Benin, Ghana, Guinea, Guinea-Bissau, Nigeria and Sierra Leone may be among the most affected countries. In Eastern Africa, Kenya, Madagascar, Mozambique, Tanzania and Uganda may constitute a cluster of sending countries of environmental migrants. In Southern Africa, Angola and Botswana could become important sources of environmental migrants while Congo and Gabon could also be pointed out in Central Africa. Without jumping too quickly to predictive conclusions, such a centripetal pattern of flows could warn about some potential destabilizing effects. On the one hand, massive population movements could speed up the transmission of epidemic diseases such as e.g. malaria (Montalvo and ReynalQuerol, 2007) in areas where the population has not yet developed protective genetic modifications (Boko et al., 2007). On the other hand, the expected move towards mainland Africa where population density has been recognized as a factor enhancing conflict could become a major geopolitical concern; for instance, North-Kivu in Congo, Burundi (Bundervoet, 2009), Rwanda (Andre and Platteau, 1998), and Darfur (Fadul, 2006).

More here (pdf)