SIMULATING THE IMPACT OF CLIMATE-CHANGE ON RICE PRODUCTION IN ASIA AND EVALUATING OPTIONS FOR ADAPTATION

The likely effects of Climate change caused by increasing atmospheric carbon dioxide levels on rice production in Asia were evaluated using two rice crop simulation models, ORYZA1 and SIMRIW, running under 'fix ed-change' climate scenarios and scenarios predicted for a doubled-CO2 (2 x CO2) atmosphere by the General Fluid Dynamics Laboratory (GFDL), the Goddard Institute of Space Studies (GISS) and the United Kingdom Meteorological Office (UKMO) General Circulation Models. In general, a n increase in CO2 level was found to increase yields white increases i n temperature reduced yields. Overall rice production in the region wa s predicted by the ORYZA1 model to change by +6.5, -4.4 and -5.6% unde r the GFDL, GISS and UKMO 2xCO(2) scenarios, respectively, while the c orresponding changes predicted by the SIMRIW model were +4.2, -10.4 an d -12.8%. The average of these estimates would suggest that vice produ ction in the Asian region may decline by -3.8% under the climate of th e next century. Declines in yield were predicted under the GISS and UK MO scenarios for Thailand, Bangladesh, southern China and western Indi a, while increases were predicted for Indonesia, Malaysia, and Taiwan and parts of India and China. Modification of sowing dares at high lat itudes, where warmer temperatures allowed a longer growing season, per mitted a possible transition from single-cropping to double-cropping a t some locations, an adaptation that could potentially have a targe po sitive impact on national rice production in some countries. Planting dates could also be adjusted to avoid high temperatures at the time of flowering which can cause severe spikelet sterility in some varieties , although a delay in planting in some cases may prevent a second crop from being obtained because of high temperatures later in the season. Selection for varieties with a higher tolerance of spikelet fertility to temperature was shown to be capable of restoring yield levels to t hose predicted for current climates. The use of longer-maturing variet ies to take advantage of longer growing seasons at higher latitudes ma y instead result in lower yields, due to the grain formation and ripen ing periods being pushed to less favorable conditions later in the sea son. A better strategy might be to select for shorter-maturing varieti es to allow a second crop to be grown in these regions. (C) 1997 Publi shed by Elsevier Science Ltd.