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Flood damage from rising seas due to global warming could hit $482 billion: researchers

A coastline on the Mekong Delta in Vietnam, which is feared to be hit by floods caused by sea level rises, is seen in this photo provided by Makoto Tamura, associate professor of environmental policy at Ibaraki University. Coastal erosion is advancing and dikes are built and rebuilt, according to Tamura.

TOKYO -- Damage from floods due to sea level rises as a result of global warming could reach up to $482 billion, or some 52.5 trillion yen, on a global scale at the end of the current century, according to an estimate by a team of Japanese researchers including from Ibaraki University.

The damage could be reduced to 60 to 70 percent if 1-meter-high dikes are built to lessen the damage although the cost of construction of such facilities could be as much as $203 billion, or approximately 22.1 trillion yen, according to the team's report published in an international online journal on climate change.

Associate professor Makoto Tamura of environmental policy at Ibaraki University, who led the research team, urges that such infrastructure should be planned from a long-term perspective.

"Apart from the costs of building and rebuilding infrastructure such as dikes, the effects of global warming decades later should also be considered in planning such facilities," Tamura says.

A report by the U.N. Intergovernmental Panel on Climate Change predicts that sea levels will rise by 26 to 82 centimeters from 1986-2005 levels by the end of the 21st century unless effective measures to reduce greenhouse gas emissions are implemented and global warming continues.

The research team has warned that if sea levels rise by 50 centimeters by 2100, floods at high tide during spring tide could affect up to 420,000 square kilometers globally, mainly areas around river mouths and low-lying areas. The Yangtze River Delta in China that includes Shanghai and the Mekong Delta in Vietnam are feared to be hit particularly hard, which could affect up to 106 million people and cause $169 billion to $482 billion worth of damage to infrastructure and agriculture.

The researchers also estimated the costs of building and managing dikes and their effectiveness of lessening the damage. If dikes 1 meter high above sea level are to be built in areas feared to be affected, the amount of damage from such disasters could be reduced to $110 billion to $329 billion.

Since such dikes have already been built in some areas, the actual costs will likely be lower than this estimate.

(Japanese original by Ai Oba, Science & Environment News Department)

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