Climate change, slow onset events and human mobility: reviewing the evidence

The breadth of emerging case studies and empirical evidence linking slow onset events and human mobility (migration and displacement) is difficult to succinctly summarize, owing to the wide range of slow onset hazards, their impacts, their varied interactions with other drivers of population movement, and the specificity of local contexts. Nevertheless, the growing literature demonstrates that the effects of slow onset processes interact with social, political, economic, environmental, and demographic factors to drive both human migration and displacement. One of the major impacts of slow onset events evident in the literature is the disruption of local livelihoods, particularly for those people dependent on natural resources, e.g. farmers, fishers, and pastoralists. Commonly, this underpins empirical case studies related to economic, more ‘voluntary’ migration patterns, yet these events may also contribute to displacement by decreasing ecosystem services and overwhelming populations’ capacity to withstand both slow- and rapid-onset events. The combination of these impacts can lead local communities to reach climatic and social tipping points, at which the socio-ecological capacity to cope in situ is exceeded, leading to displacement.

This synthesis article, therefore, distinguishes between displacement and more voluntary forms of migration in slow onset contexts related to climate change, while acknowledging that a clear distinction between migration and displacement is often blurred in the context of slow-onset events such as sea-level rise, desertification and land and forest degradation. It recognizes that slow-onset events may in many situations interact or exacerbate rapid-onset events in multi-risk scenarios, increasing the risk of loss and damage. The article assesses the state of knowledge on human mobility related to slow onset events by distilling academic and ‘grey’ literature across geographical regions, with particular attention given to developing country contexts. It will draw from various secondary and bibliographic resources including the CLIMIG database. This contribution identifies commonalities as well as gaps and tensions in the field at different spatial scales, in order to provide scientific information that can support and inform national planning and policymaking processes in assessing and addressing the mobility impacts and risks associated with slow onset events.