Joint Impacts of Heat and Moisture on Global Crop Yields

The damaging effects of extreme heat and drought events on crop yields pose a risk to global food production in a warming climate. However, growing season temperatures are strongly correlated with both precipitation and soil moisture over the majority of global croplands. This correlation raises questions about the separability of temperature and moisture stresses on crop yields and the influence of soil moisture-temperature couplings on local yield sensitivity to weather. In this research, we examine these impacts of temperature-moisture covariability on global crop yields. We demonstrate that previously-quantified impacts of extreme heat on crops include a signal from moisture stress. We also identify a global dependence of local yield sensitivity to temperature on the magnitude of soil moisture-temperature coupling. Our findings are important for two reasons. Firstly, they suggest that temperature-based statistical yield projections likely underestimate the role of changing dependence between moisture and temperature and mounting probability of concurrent heat-drought events in a warming climate. Secondly, they indicate that climate change adaptations should be informed by the complex physiological responses of crops to compound heat and moisture stress. Our results support a more holistic consideration of moist thermodynamics in the crop canopy for anticipating future impacts of climate change on crop yields.