Geography of Climate Change Adaptation in U.S. Agriculture

Geography is a salient feature in agricultural adaptation to a warming climate. Facing heterogeneous natural-resource and climatic endowments, farmers in different locations choose adaptive strategies that best suit their environments, leading to spatially inhomogeneous adaptation outcomes. We provide novel evidence of this explicitly spatial heterogeneity in heat sensitivity of U.S. crops and their adaptation thereto. We generalize a popular “long differences” methodology by explicitly incorporating local geographic information in a flexible semiparametric fashion, which enables us to control for spatially clustered local heterogeneity that may be non-neutral in that it can mediate climate effects on agriculture by shifting all parameters—intercept and slopes—in the crop-climate relationship. We find that for corn (soybeans, cotton), 54% (75%, 23%) of producing counties experienced a decline in overheat sensitivity, 12% (2%, 77%) experienced an increase, and 34% (23%, 0%) no change over 1958–2019. Corn and soybean adaptation to overheat mainly occurred in the Northern Great Plains and Upper Midwest; for cotton, it occurred in Arkansas, Louisiana, and Mississippi. Accounting for this spatial heterogeneity, we find a clear geographic bifurcation in expected climate change effects on yields by the mid-century, which results in much smaller average yield impact projections compared to traditional approaches