Effect of 2 × CO₂ climatic warming on water temperature and agricultural potential in China

The most notable results are that the safe transplanting date for rice plants would be 20-30 dasys earlier than that under present climatic conditions: the rice cultivation period would be prolonged by 30-50 days, and the increase in effective accumulated water temperature is >700-1200 degree days in the mid-arid region of China and 1300-2000 degree days in main rice-producing areas of the southern part of China. This indicates that the northern limit of the safe cultivable area of India 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 16-40%. However, the GCM-2 × CO₂ 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. -from Authors