Climate Impacts and Vulnerabilities, Potsdam Institute for Climate Impact Research (PIK), 14473 Potsdam, Germany.
Department of Agronomy, Iowa State University, Ames, Iowa 50011, USA.
Nat Commun. 2017 Jan 19;8:13931. doi: 10.1038/ncomms13931.
High temperatures are detrimental to crop yields and could lead to global warming-driven reductions in agricultural productivity. To assess future threats, the majority of studies used process-based crop models, but their ability to represent effects of high temperature has been questioned. Here we show that an ensemble of nine crop models reproduces the observed average temperature responses of US maize, soybean and wheat yields. Each day >30 °C diminishes maize and soybean yields by up to 6% under rainfed conditions. Declines observed in irrigated areas, or simulated assuming full irrigation, are weak. This supports the hypothesis that water stress induced by high temperatures causes the decline. For wheat a negative response to high temperature is neither observed nor simulated under historical conditions, since critical temperatures are rarely exceeded during the growing season. In the future, yields are modelled to decline for all three crops at temperatures >30 °C. Elevated CO can only weakly reduce these yield losses, in contrast to irrigation.
高温不利于作物产量，可能导致全球变暖导致农业生产力下降。为了评估未来的威胁，大多数研究都使用了基于过程的作物模型，但它们对高温影响的表示能力一直受到质疑。在这里，我们展示了一个由九个作物模型组成的集合，可以再现美国玉米、大豆和小麦产量的观测到的平均温度响应。在雨养条件下，每天超过 30°C，玉米和大豆的产量最多减少 6%。在灌溉地区观察到的下降，或假设完全灌溉的情况下模拟的下降则较弱。这支持了高温导致水分胁迫从而引起减产的假设。对于小麦，在历史条件下，既没有观察到也没有模拟到高温的负面响应，因为在生长季节很少有临界温度超过。在未来，所有三种作物的产量在超过 30°C 的温度下都将下降。与灌溉相比，升高的 CO 只能微弱地减少这些产量损失。
