Coming to Terms with Deep Uncertainty in the Study of Climate-Related Displacement

On average, an estimated 20 million people each year are displaced by climate-related hazards. This number will increase in coming years due to global warming, sea level rise, and rapid population growth in areas highly exposed to floods, storms and droughts. Future levels of displacement will depend on future greenhouse gas emissions, future development trajectories in low- and middle-income countries, and future government migration and mobility policies. Given the rapidity of atmospheric change, there are likely also ‘unknown unknowns’ factors that could cause unexpectedly large and/or sudden displacements. This article reviews what scholars know about how climate affects displacement; what is known or suspected but important data are lacking; and other considerations that are understood poorly or not presently observable. Particular attention is given to reflecting on how scholars can advance research on climate-related displacement under conditions of deep uncertainty, with suggestions on ways to shed light on ‘unknown unknowns’.