Adaptation through diversification : crop diversity and the resilience of U.S. agricultural yields to weather shocks

We combine 2008-2023 county-level yield data with 30-meter crop classification imagery to test whether crop diversity mitigates yield losses from weather shocks. Diversity is measured with the exponential Shannon index, capturing county-level species richness and evenness as the effective number of crops. Two-way fixed-effects regressions replicate standard nonlinear damages from extreme heat and precipitation, but show that each additional effective crop attenuates heat impacts for corn and soybean and moderates winter wheat losses in unusually wet years. Resilience benefits are concentrated in rainfed counties, where irrigation offers limited protection, indicating that diversification can complement water-based adaptation to climate change.