Climate Matters @ Columbia

Could climate change cause the greatest human migration in history? A new report says that millions of people around the globe have already been forced to relocate due to climate-related impacts, and it explains why hundreds of millions more may be displaced in the next few decades.

The report, written by researchers at the Center for International Earth Science Information Network (a Columbia Climate Center partner), the United Nations University Institute for Environmental Human Security, and CARE International, presents evidence from the first multi-continent survey of environmental change and human mobility along with original maps of climate change impacts and population distributions.

Most migration is caused by a combination of factors, the report says, but climate change and other environmental degradation will play an ever-more important role in uprooting people. Though it is impossible to draw a direct causal link between global mean temperatures and population movements, the report draws upon “current scientific understanding of environmental processes and how these processes can affect human mobility.”

The hardest hit are likely to be groups of poor people who depend on ecosystem services for their livelihoods, like farmers, fishermen and herders, who will be forced to move in search of new income sources. But, cautions the report, migrants may not have the money to flee far enough to avoid degraded lands, as “case studies indicate that poorer environmental migrants can find their destinations as precarious as the places they left behind.”

This map shows areas of sea level rise at 1 and 2 meters (dark and light blue, respectively) along with population density. More than 10 million people live in areas of the Nile delta that could be inundated by a 2 meter sea level rise. The inset shows the area under farmland.

Most migrants will move within their own country or region and, following an already well-trod pattern of rural-to-urban migration, many of them will head to cities. In turn, urban areas will face increasing population pressure. Since many large cities are coastal, the urban population uptick may coincide with future crises resulting from climate-induced sea level rise, including major infrastructure challenges from rising water.

As a further issue, environmental migrants are unlike political refugees who can return home after the conflict they fled has died down; rather, people displaced by the chronic impacts of climate change can probably never resettle the places they left.

The report offers a set of policy recommendations to address both the causes of climate-related migration and the wellbeing of the migrants. The authors advise investment in adaptation measures like irrigation and income diversification as strategies to undermine the effects that severe climate impacts can have on livelihoods. They also recommend that governments keep probable migration in mind as they build their climate adaptation plans, including, for example, provisions for rights-based resettlement of highly threatened populations. Of course, the authors also emphasize the importance of reducing global greenhouse gas emissions to mitigate climate change. They even suggest that historically high-emitting countries should subsidize sustainable resettlement from vulnerable areas as part of larger adaptation plans.

Click here for the full report, including seven regional climate change and human mobility case studies.

Images from “In search of shelter: mapping the effects of climate change on human migration” © 2008 Cooperative for Assistance and Relief Everywhere, Inc. (CARE). Used by permission. Maps created by CIESIN-Columbia University.