气候变化对中国农业温度阈值影响研究及其不确定性分析

The Threshold of Temperature Increase Due to Climate Change for Chinese Agriculture and Its Uncertainties

气候变化影响的温度阈值已经成为国际谈判的焦点问题。利用区域气候模式和作物模型相连接的方法，在50km×50km的网格尺度上模拟了IPCC（International Panel of Climate Change）SRES（Spccial Report on Emissions Scenarios）A2和B2情景下2011—2040年、2041--2070年和2071—2100年我国3种主要粮食作物（水稻、小麦和玉米）的平均单产变化情景，结合同时段的中国地区温度升高状况分析了造成我国主要粮食作物产量持续下降的升温阈值，并对阀值研究中的不确定性进行了初步分析。结果表明：如果同时考虑升温和CO2的肥效作用对作物的影响，目前预测的气温升高范围（0．9～3．9℃）中将不存在威胁我国粮食生产的温度阈值；而如果仅考虑升温对作物的影响时，全国平均温度升高2℃以后，将导致我国粮食单产水平的持续下降，威胁未来的粮食生产；气候变化适应措施如充分灌溉、播种期的调整和品种更替对闽值的确定有一定的影响，如单考虑充分灌溉可以使上述升温阈值延后到2．5℃左右，而播种期的调整和品种的更替也会对产量和产量变率造成一定的影响，进而调整温度闽值；目前研究的不确定性主要来源于情景、方法和适应措施3个方面。

The determination of critical thresholds＇is an essential task for informed policy decisions on establishing greenhouse emission targets. The threshold of temperature increase due to greenhouse gas enrichment has become the key point of negotiation of climate change. By using the A2 and B2 climate scenarios produced by Regional Climate Model PRCIS, modified crop model-CERES, the threshold of temperature increase under climate change for Chinese food production and its uncertainties were simulated and analyzed based on the yield variation of three main food crops （rice, wheat and maize）. Result shows： there is no temperature increase threshoid if the interactive effects of temperature increase and elevated CO2 concentration were considered in the analysis ; the temperature increase threshold emerges in 2℃ if only the effect of temperature increase was included in the simulation; the adaptation can mitigate the negative effect of climate change on grain production. If irrigation pushes the above-mentioned threshold to 2.5℃, early sowing and changing to middle-growth cuhivars increase the yield and decrease the yield variability, and modify the threshold also. There are three kinds of uncertainties in this assessment： scenarios, methods, and adaptation. The effects of CO2 enrichment and climate change need further study.