Global Warming Projection for Japan: More Frequent Extremely Hot Days, Intense Rainfall Events

Japan Meteorological Agency (JMA) released on March 15, 2013, the eighth volume of its Global Warming Projection Studies, which provide detailed forecasts of global warming effects in Japan. JMA has made public the results of forecasts on global warming effects since 1996, in an effort to contribute to considering mitigation and adaptation measures against global warming. The latest forecasts are based on a new, more precise climate model, which enables a projection of the incidence of intense rainfall events for the first time.

The forecasts indicate that Japan's annual average temperature will be between 2.5 to 3.5 degrees Celsius higher by the end of the twenty-first century than the average recorded at the end of the twentieth century. It is also predicted that, during the same period, the number of extremely hot days (when the highest temperature reaches or exceeds 35 degrees Celsius) will increase by an average of 7.6 days nationally. In addition, the incidence of heavy rain and intense rainfall events (hourly rainfall of 50 millimeters or higher) will increase, whereas the number of days with no rainfall will also increase.

For the projection, JMA adopted future greenhouse gas concentrations, which are the basis for global warming projections, using the A1B scenario of the Special Report on Emissions Scenarios (SRES A1B) compiled by the Intergovernmental Panel on Climate Change (IPCC). The SRES A1B has been established on the assumption of a society that will place emphasis on the balance of all energy sources, in which high economic growth will continue and regional economic gaps will narrow. The concentration of carbon dioxide is predicted to increase by 1.8 times by the end of the twenty-first century, compared with the current concentration level.

Related JFS article:
Climate Model Predicts Longer Rainy Season in Future Japan
Preparation for IPCC AR5 Underway, New Insights into Climate Change Projection Released
Three Government Bodies Release Joint Report on Japan's Climate Change and its Impact