Why the numbers don’t add up: A review of estimates and predictions of people displaced by environmental changes

Estimates and predictions of people displaced by environmental changes have been highly instrumental in the ever-increasing attention given to environmental migration in the media. Yet no consensual estimate exists, let alone a commonly agreed methodology. As a result, predictions and estimates have become one of the most contentious issues in the debates on environmental migration. This article seeks to review the key estimates and predictions existing in the literature, as well as the methodologies they are built on, and the problems and caveats they are fraught with. The first part reviews the figures related to current estimates of people displaced by environmental changes, while a second part examines the predictions for future displacements. The next section synthesises the key methodological difficulties and a final section suggests some possible avenues for improvement.

► Estimates and predictions have been highly instrumental in the media.
► Such numbers are not based on robust methodologies.
► Some ways forward exist however, and methodologies could be greatly improved.