The annual cost of damage caused by flooding in Japan is estimated to triple by the end of this century to ¥680 billion due to global warming, a government research team said Monday.

A rise in the average annual temperature of between 3.5 and 6.4 degrees from 100 years earlier is likely to raise the sea level about 60 cm by the end of the 21st century, causing around 85 percent of sand beaches across Japan to disappear, the team at the Environment Ministry reported.

The rise in temperature is projected to double the nationwide death toll from heat around the middle of the century, and enable subtropical plants to grow in a wider area of the country, including Tokyo.

Deriving its projections from four recent computer-aided simulations on climate change, the team stressed the importance of curbing the volume of greenhouse gas emissions and taking proper measures to reduce possible damage.

Nobuo Mimura, a professor of environment studies at Ibaraki University who headed the research team, said that while the damage will depend on how fast global warming takes place, Japan needs to curb greenhouse gas emissions.

"We could anticipate negative effects far worse than present even if the rises in temperature can be subdued," Mimura said.