干旱区生态环境知识资源中心

Water temperature under the current and future climates are estimated using the water temperature physical model, weather data and general circulation model (GCM)-scenarios to assess effects of CO2-induced climatic changes on the natural environment surrounding the agriculture of China. The most notable results obtained for the GCM-2xCO(2) scenarios are that the safe transplanting date for rice plants would be about 20-30 days earlier than that under present climatic conditions. This means that the rice cultivation period would be prolonged by approximately 30-50 days, and also that the increase in effective accumulated water temperature is more than 700-1200 degree days in the semi-arid region of China and 1300-2000 degree a days in main rice-producing areas of the southern part of China. This indicates that the northern limit of the safely cultivable area of Indica and hybrid rice cultivars may reach on the south of Huang He, indicating the increment in the potential rice production of China. On the other hand, these changes in temperature environment of shallow water due to CO2-climate warming could cause an increase in evaporation from water surface. The increase in evaporation due to the future climatic warming is about 16-40% However, the GCM-2xCO(2) scenarios indicate that the mean increasing rate of precipitation due to climatic change would be only 15-20% by the middle of the 21st century. Therefore, the imbalance of water to be expected in the next century may cause a shortage of water resources available for paddy rice cultivation.