CHANGES IN THE EXTREMES OF THE CLIMATE SIMULATED BY CCC GCM2 UNDER CO2 DOUBLING

Changes due to CO2 doubling in the extremes of the surface climate as simulated by the second-generation circulation model of the Canadian C entre for:Climate Modelling and Analysis are studied in two 20-yr equi librium simulations. Extreme values of screen temperature, precipitati on, and near-surface wind in the control climate are compared to those estimated from 17 yr of the NCEP-NCAR reanalysis data and from some C anadian station data. The extremes of screen temperature are reasonabl y well reproduced in the control climate. Their changes under CO2 doub ling can be connected with other physical changes such as surface albe do changes due to the reduction of snow and sea ice cover as well as a decrease of soil moisture in the warmer world. The signal in the extr emes of daily precipitation and near-surface wind speed due to CO2 dou bling is less obvious. The precipitation, extremes increase almost eve rywhere over the globe. The Strongest change, over northwest India, is related to the intensification of the summer monsoon in this region i n the warmer world. The modest reduction of wind extremes in the Tropi cs and middle latitudes is consistent with the reduction of the meridi onal temperature gradient in the 2xCO(2) climate. The larger wind extr emes occur in the areas where sea ice has retreated.