This article presents a conceptual model to investigate population migration as a possible adaptive response to risks associated with climate change. The model reflects established theories of human migration behaviour, and is based upon the concepts of vulnerability, exposure to risk and adaptive capacity, as developed in the climate change research community. The application of the model is illustrated using the case of 1930s migration patterns in rural Eastern Oklahoma, which took place during a period of repeated crop failures due to drought and flooding.

Anthropogenic sea-level rise (SLR) is predicted to impact, and, in many cases, displace, a large proportion of the population via inundation and heightened SLR-related hazards. With the global coastal population projected to surpass one billion people this century, SLR might be among the most costly and permanent future consequences of climate change. In this Review, we synthesize the rapidly expanding knowledge of human mobility and migration responses to SLR, providing a coherent roadmap for future SLR research and associated policy. While it is often assumed that direct inundation forces a migration, we discuss how mobility responses are instead driven by a diversity of socioeconomic and demographic factors, which, in some cases, do not result in a migration response. We link SLR hazards with potential mechanisms of migration and the associated governmental or institutional policies that operate as obstacles or facilitators for that migration. Specific examples from the USA, Bangladesh and atoll island nations are used to contextualize these concepts. However, further research is needed on the fundamental mechanisms underlying SLR migration, tipping points, thresholds and feedbacks, risk perception and migration to fully understand migration responses to SLR.

Migration is one of the variety of ways by which human populations adapt to environmental changes. The study of migration in the context of anthropogenic climate change is often approached using the concept of vulnerability and its key functional elements: exposure, system sensitivity, and adaptive capacity. This article explores the interaction of climate change and vulnerability through review of case studies of dry-season migration in the West African Sahel, hurricane-related population displacements in the Caribbean basin, winter migration of ‘snowbirds’ to the US Sun-belt, and 1930s drought migration on the North American Great Plains. These examples are then used as analogues for identifying general causal, temporal, and spatial dimensions of climate migration, along with potential considerations for policy-making and future research needs.

Once it was an environmental issue, then an energy problem, now climate change is being recast as a security threat. So far, the debate has focused on creating a security ‘hook’, illustrated by anecdote, to invest climate negotiations with a greater sense of urgency. Political momentum behind the idea of climate change as a security threat has progressed quickly, even reaching the United Nations Security Council. This article reviews the linkages between climate change and security in Africa and analyses the role of climate change adaptation policies in future conflict prevention. Africa, with its history of ethnic, resource and interstate conflict, is seen by many as particularly vulnerable to this new type of security threat, despite being the continent least responsible for global greenhouse gas emissions. Projected climatic changes for Africa suggest a future of increasingly scarce water, collapsing agricultural yields, encroaching desert and damaged coastal infrastructure. Such impacts, should they occur, would undermine the ‘carrying capacity’ of large parts of Africa, causing destabilizing population movements and raising tensions over dwindling strategic resources. In such cases, climate change could be a factor that tips fragile states into socio‐economic and political collapse. Climate change is only one of many security, environmental and developmental challenges facing Africa. Its impacts will be magnified or moderated by underlying conditions of governance, poverty and resource management, as well as the nature of climate change impacts at local and regional levels. Adaptation policies and programmes, if implemented quickly and at multiple scales, could help avert climate change and other environmental stresses becoming triggers for conflict. But, adaptation must take into account existing social, political and economic tensions and avoid exacerbating them.

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