There are a lot of predictions about how many people will migrate in response to climate change. Depending on where you look, the next few decades could see hundreds of millions – or even more than a billion – people pick up and move. We asked Julia Blocher, of the Potsdam Institute for Climate Impact Research, to explain why the predictions vary so much. We also discussed how this movement can lead to conflict.

The relationship between climate change and migration is long and complex. Human civilizations have been affected by environmental conditions for centuries, but we should be wary of arguments that huge numbers of people are inevitably destined to migrate in response to specific climate threats. In this episode, we chat with Alex de Sherbinin of Columbia University’s Center for International Earth Science Information Network about what the research shows – and doesn’t show.