A World Bank study has found that a three-foot rise in sea levels from global warming would force about 60 million people in developing countries to abandon their homes as waters submerged large swaths of coastal areas.
Rising sea levels would have the most drastic effect on populations in the Middle East, North Africa and East Asia, the study found, with inundation displacing about a tenth of the people from countries with large settlements in river delta areas such as Egypt and Vietnam.
The study, released Tuesday, used satellite maps and data to calculate the effect in 84 coastal developing countries. World Bank officials said they hoped their report would help international organizations and the countries affected plan for inevitable rises.
A three-foot rise by the end of this century would reflect the high end of scientific estimates. The U.N. Intergovernmental Panel on Climate Change, or IPCC, which recently found a 90 percent certainty that human activity has caused escalating temperatures, projected that sea levels would rise by 7 to 23 inches by the end of this century.
A significantly larger rise could occur if ice sheets continue to melt. Other recent scientific papers have projected more dramatic rises, including a study published in the peer-reviewed journal Science, which estimated a rise of between 20 and 55 inches by 2100.
Because carbon dioxide stays in the atmosphere for 100 years, sea levels will continue to rise for centuries to come, studies including the IPCC's have said.
"Knowing which countries will be most affected could allow better targeting of scarce available resources and could spur vulnerable nations to develop national adaptation plans now and avoid big losses later," one of the report's authors, Susmita Dasgupta, said in a statement. Relatively little has been done in developing countries so far, she said.
The World Bank's study calculated effects on people, economies, cities and farmlands that would occur at various sea level increases, ranging from three to 15 feet.
A rise of three feet would force more than 3 percent of the population in the Middle East and North Africa to leave coastal areas for higher ground, the report estimates. Nearly two percent of people living in all of East Asia would be affected.
In Egypt, much of the Nile Delta would be inundated, enveloping cities like Alexandria unless steps were taken to hold back the waters. The submerged area would displace more than nine percent of the population and wipe out more than six percent of the economy.
Large parts of Vietnam, including the Mekong Delta, would become submerged under the scenario, with nearly 11 percent of the population losing their homes and more of 10 percent of the economy destroyed. More than 10 percent of urban areas and seven percent of agricultural lands would be lost, the report found.
Overall, a three-foot rise would inundate 74,900 square miles and 1.28 percent of the populations in 84 developing countries, the study estimated.