When Heat Meets Drought: How Compound Climate Exposure Affects Grain Yield Anomalies

Compound heat–drought (CHD) exposure poses a growing risk to grain production safety under climate change. Using a panel of Chinese cities from 2010 to 2024, we estimate its effects on grain yield anomalies. We also test whether the compound effect exceeds the sum of heat-only and drought-only exposure. Greater CHD exposure shifts grain yield anomalies toward more negative values, indicating larger losses relative to the long-run trend. This relationship remains robust across alternative CHD definitions, alternative measures of production anomalies, and adjusted samples. The adverse effects are stronger in major grain-producing regions and areas with low topographic relief. Mediation analysis indicates that CHD exposure worsens grain yield anomalies partly by intensifying soil moisture deficits. Irrigation capacity, agricultural technological innovation, agricultural insurance coverage, and agricultural organizational capacity mitigate these effects. They operate through resource provision, technological adaptation, risk sharing, and organizational coordination. The adverse effect of CHD exposure also exceeds the additive effects of heat-only and drought-only exposure, indicating synergistic damage amplification. These findings show how compound climate extremes generate grain yield anomalies. They also highlight the need to strengthen agricultural adaptive capacity and tailor climate risk management policies to safeguard food security.