East Sea to Turn Into `Dead Sea` in 100 Years: Report

Japanese researchers say the East Sea will turn into an oxygen-less body of water like the Dead Sea in 100 years, the Japanese daily Mainichi Shimbun said Tuesday.

Water on the sea surface, which cools off in winter, circulates and conveys oxygen to the deep sea, and surface water will not adequately cool off due to global warming, the study said. This in turn will block the seamless circulation of water.

A survey of cumulative data since the 1920s by Japan’s National Institute for Environmental Studies and the Japan Agency for Marine-Earth Science and Technology found that dissolved oxygen in surface water has continued to decline since the 1950s and 60s. Oxygen density is 6.7 milligrams per kilogram of seawater, about 20 percent down from the 1950s.

According to the research team, considering that global warming has increased seawater temperatures in the East Sea 1.3 to 1.7 degrees Celsius over the past century, the area near the sea bottom will end up with no oxygen at all within 100 years.

Prolonged suspension of oxygen will kill organisms in the sea, rendering it impossible for microorganisms that dissolve such organisms to survive. As a result, the sea will eventually turn into a “Dead Sea,” the researchers said.

Previous studies also suggested the decline of dissolved oxygen levels in the East Sea, but the latest survey is different in that the time required for the sea to become oxygen-free has fallen from 170 to 350 years to 100 years.

changkim@donga.com