global warming, rising seas and “the three Ms”
Climate change: study maps those at greatest risk from cyclones and rising seas
The first global study to identify populations at greatest risk from rising sea levels and more intense cyclones linked to climate change will be published next month in the peer-reviewed journal Environment and Urbanization.
The research shows that 634 million people — one tenth of the global population — live in coastal areas that lie within just ten metres above sea level.
It calls for action to limit the effects of climate change, to help people migrate away from risk and to modify urban settlements to reduce their vulnerability. But it warns that this will require enforceable regulations and economic incentives, both of which depend on political will, funding and human capital.
Key findings of the study by Gordon McGranahan of the International Institute for Environment and Development (UK) and his colleagues, Deborah Balk and Bridget Anderson, at the City University of New York and Columbia University, are that:
§ Nearly two-thirds of urban settlements with more than 5 million inhabitants are at least partially in the 0-10 metre zone.
§ On average, 14 percent of people in the least developed countries live in the zone (compared to 10 percent in OECD countries).
§ 21 percent of the urban populations of least developed nations are in the zone (11 percent in OECD countries).
§ About 75% of people in the zone are in Asia. 21 nations have more than half of their population in the zone (16 are small island states).
§ Poor countries — and poor communities within them — are most at risk.
§ The ten countries with the largest number of people living within ten metres of the average sea level are:
Indonesia (41,610,000); Japan (30,477,000);
United States (22,859,000);
Thailand (16,468,000); and the
§ The ten countries with the largest share of their population living within ten metres of the average sea level are:
Egypt (38%); and the
The new study highlights the importance of “the three Ms”: mitigation, migration and modification.
“It is too late to rely solely on a reduction in greenhouse gas emissions to mitigate climate change, although this is clearly an imperative,” says McGranahan. “Migration away from the zone at risk will be necessary but costly and hard to implement, so coastal settlements will also need to be modified to protect residents.”
[The study will be published on 14 April along with papers that focus on specific cities, including Cotonou (Benin), Dhaka (Bangladesh), Mumbai (India) and Shanghai (China).]
More than 100 million people live on land within one meter (three feet) of sea level. Some island countries such as the Seychelles off the East Coast of Africa are mostly less than one meter above sea level. It is estimated that a rise of 1 meter would put half of the land of Bangladesh underwater. Although there are local variations in sea level the key question is what is happening to the volume of ocean water worldwide. The major determining factor is the amount of water in glaciers on land, especially in Greenland and Antarctica.