Photo/IllutrationThe Asahi Shimbun

Global warming could lead to the formation of powerful typhoons that are 20 percent larger than current ones by the end of the century, according to researchers using the “K” supercomputer.

The prediction was made by researchers with the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), the University of Tokyo and the Japan Meteorological Agency's Meteorological Research Institute.

Computer simulations of the impact of global warming have indicated that powerful typhoons will account for a larger portion of all typhoons, which will shrink in number.

However, the change anticipated in the structure of typhoons remained largely unknown because of the complexity of the calculations required, the researchers said.

Using a numerical simulation conducted on the K supercomputer, Yohei Yamada, a JAMSTEC researcher, and his colleagues modeled the Earth with a sphere covered with a mesh of equilateral triangles of 14 kilometers per side.

They compared typhoons from 1979 to 2008 with typhoons expected to form from 2075 to 2104, when global warming will have pushed up sea-surface temperatures by 1.3 degrees on average.

The simulation showed that powerful typhoons, measuring up to 945 hectopascals in terms of minimum air pressure at the eye, will have about 23 percent larger areas of winds with speeds of 43.2 kph or more.

Global warming raises the altitude limit where cumulonimbus-type clouds can develop. That will widen the body of typhoon clouds and increase the volume of air that expands due to heat generated when those clouds are formed.

This will lower the air pressure and broaden the areas of strong winds relative, the scientists said.

Their research results were published Sept. 14 in the U.S. Journal of Climate.