The climatic factors have been changing very rapidly in Malaysia. The average temperature in the rice growing areas in Malaysia is about 26°C. Under current climatic change scenario, temperature above 25°C may cause decline in grain mass by 4.4% per 1°C rise in temperature and grain yield may decline as much as 9.6 - 10.0% per 1°C rise showed that in Malaysia, the actual yield of paddy rice per hectare varied from 3-5 tons, when the potential yield is 7.2 tons. There is a decline of paddy rice yield between 4.6 - 6.1% per 1°C temperature increase under the present CO2 level. But a doubling of CO2 concentration (from present level of 340-680ppm) may offset the detrimental effect up to 4°C temperature increase.