A new World Bank report projects that tens to hundreds of millions of people fleeing the gradual effects of climate change will shift centers of population within many countries in Latin America, South Asia and sub-Saharan Africa. If emissions of greenhouse gases remain high, as many as 143 million “internal migrants” might move within their own countries, comprising as much as 3.5 percent of the total population of the studied regions by 2050, according to the report. It says such movements could accelerate after 2050.
The report is the first ever attempt to model climate change-induced migration over large geographic areas. Notably, it leaves out large numbers of additional people who might also be displaced: people fleeing the effects of short-term climate-related shocks such as cyclones, floods and droughts, and refugees who might cross international borders within the studied regions. It also does not cover more northerly parts of the world where similar migrations might also occur.
According to the report, many migrants will relocate within their countries from lowlands to higher ground, forced to move by rising sea levels and storm surges, along with lowered crop productivity due to increasing heat and declining water availability. The effects will be evident by 2030, it says, and gradually increase. The new report is the latest in a growing body of research predicting that climate change will soon displace large numbers of people.
“These are relatively conservative estimates that should be considered lower bounds,” said coauthor Alex de Sherbinin, a researcher at Columbia University’s Center for International Earth Science Information Network (CIESIN).
The report estimates that under more optimistic scenarios, where global warming is slowed by collective action among nations and nations take strong actions to adapt to changes, the number of internal migrants might number as few as 26 million in the studied regions.
In any scenario, the highest numbers of migrants are expected to be in sub-Saharan Africa, where people are often already living on the edge and would not be able to adapt to further climate-related pressures. The lowest are expected in Latin America, where economies are stronger, and societies will have more capability to adapt by modifying infrastructure or agriculture. In South Asia, the report says, migration will be driven largely by Bangladesh, where much of the population lives along rivers and coasts already very close to sea level. India is expected also to see substantial movements to the interior.
Many people are projected to end up in big cities and their outskirts, continuing a long-term global trend of increasing urbanization. Big African cities like Kampala and Nairobi are expected to boom. So are India’s Hyderabad and Chennai. However, the megacities of Dar es Salaam, Tanzania and Dhaka will grow less slowly or could conceivably even lose people, because they are afflicted by coastal hazards and the impacts of climate on water supplies and crop production. In Mexico, Guatemala and El Salvador, hot rural lowland areas are projected to become increasingly uncomfortable and agriculturally unproductive, to the extent that they could lose population. People there would probably move to higher elevations both in urban and rural areas.
The World Bank commissioned the report to help countries plan future agricultural and infrastructure projects. “You don’t want to make investments in areas that could be unproductive in 20 or 30 years,” said de Sherbinin.
The report is based on a methodology developed by the City University of New York Institute for Demographic Research and the National Center for Atmospheric Research. CIESIN staff led the data analysis and visualization work, and wrote the country and regional analyses. In addition to working with World Bank staff, the CIESIN researchers also collaborated with scientists from the Potsdam Institute for Climate Impact Research and West Virginia University.