If global warming continues at its present rate, Japan will experience four months of hot summer days with temperatures over 30 degrees Celsius in the year 2100, researchers have announced. A team of researchers from the University of Tokyo's Center for Climate System Research and the National Institute for Environmental Studies used the world's fastest supercomputer, Earth Simulator, to obtain the results. They calculated that in 2100, Japan would experience 120 days of midsummer temperatures. In 2050 the number of hot summer days would reach 120. On average, Japan now has only 50 days of midsummer temperatures a year. The calculations were based on the concentration of carbon dioxide in the atmosphere increasing 1.9 times higher than the present concentration (scenario A1B) and of it increasing 1.4 times (B1). Researchers divided the earth's atmosphere and sea with grids to calculate changes in temperature. They found that the average temperature during the last 30 years of the 21st century would be 4.2 degrees higher than during the last 30 years of the 20th century under scenario A1B and 3.0 degrees higher under scenario B1. Researchers counted days in which temperatures within the grid over Japan exceeded 30 degrees Celsius as midsummer days.