Warming temperatures tend to damage crop yields, yet the influence of water supply on global yields and its relation to temperature stress remains unclear. Here we use satellite-based measurements to provide empirical estimates of how root zone soil moisture and surface air temperature jointly influence the global productivity of maize, soybeans, millet and sorghum. Relative to empirical models using precipitation as a proxy for water supply, we find that models using soil moisture explain 30–120% more of the interannual yield variation across crops. Models using soil moisture also better separate water-supply stress from correlated heat stress and show that soil moisture and temperature contribute roughly equally to historical variations in yield. Globally, our models project yield damages of −9% to −32% across crops by end-of-century under Shared Socioeconomic Pathway 5-8.5 from changes in temperature and soil moisture. By contrast, projections using temperature and precipitation overestimate damages by 28% to 320% across crops both because they confound stresses from dryness and heat and because changes in soil moisture and temperature diverge from their historical association due to climate change. Our results demonstrate the importance of accurately representing water supply for predicting changes in global agricultural productivity and for designing effective adaptation strategies.

气温升高往往会损害作物产量，但供水对全球产量的影响及其与温度胁迫的关系仍不清楚。在这里，我们使用基于卫星的测量来提供根区土壤水分和地表气温如何共同影响玉米、大豆、小米和高粱的全球生产力的经验估计。相对于使用降水量作为供水代理的经验模型，我们发现使用土壤水分的模型可以解释 30-120% 以上的作物年际产量变化。使用土壤水分的模型还可以更好地将供水压力与相关的热压力区分开来，并表明土壤水分和温度对产量历史变化的贡献大致相同。在全球范围内，我们的模型预测，到本世纪末，在共享社会经济路径 5-8.5 下，温度和土壤湿度的变化会对作物造成 -9% 至 -32% 的产量损失。相比之下，使用温度和降水量进行的预测将作物的损失高估了 28% 至 320%，这既是因为它们混淆了干燥和高温带来的压力，也是因为气候变化导致的土壤水分和温度变化与其历史关联背道而驰。我们的结果证明了准确表示供水对于预测全球农业生产力变化和设计有效适应策略的重要性。使用温度和降水的预测将作物的损失高估了 28% 到 320%，这既是因为它们混淆了干燥和高温的压力，也是因为气候变化导致的土壤水分和温度的变化与其历史关联不同。我们的结果证明了准确表示供水对于预测全球农业生产力变化和设计有效适应策略的重要性。使用温度和降水的预测将作物的损失高估了 28% 到 320%，这既是因为它们混淆了干燥和高温的压力，也是因为气候变化导致的土壤水分和温度的变化与其历史关联不同。我们的结果证明了准确表示供水对于预测全球农业生产力变化和设计有效适应策略的重要性。