Abstract: Based on a high resolution climate change simulation of the 21st century conducted by a regional climate model (RegCM3) nested with a global climate model (MIROC3.2_hires), temperature and precipitation extremes changes as measured by 20-year return values over China under the IPCC SRES A1B scenario are analyzed. Validation of the model performances in simulating present day (1981-2000) distribution of 20-year return values against the observation is firstly carried out. Results show that the model reproduced well the spatial distributions of the values. However, compared with the observation, the model showed deficiencies in simulating the magnitudes of them. Significant increase of the 20-year return values of extreme maximum temperature is found over the whole China in the model simulation, both in the middle (2041-2060) and end (2081-2100) of the 21st century, especially over the Northeast China in the end of the 21st century. Increased value for extreme minimum temperature in the future is also simulated, while the greatest increase is found over Inner Mongolia, Xinjiang and southern slope of the Tibetan Plateau. General increase of extreme precipitation value is also found both in the middle and end of the 21st century. The above changes are more profound in the end of the 21st century compared with the middle. The results indicate a general increase of the frequency and spread of heat waves, and a general decrease of the frequency and spread of extreme cold events in the future over China. Extreme precipitation events are also projected to increase in both the frequency and the spread.

Key words: climate change, regional climate model, extreme events, 20-year return values