Zimao Xiao

This paper provides new evidence of long-run climate change adaptation in US agriculture. Focusing on the past two decades, our long-difference estimates suggest modest losses due to extreme heat, even though conventional panel estimates still imply sizable heat damage. Our results indicate that emerging long-run adaptation since 2000 mitigates short-run heat impacts by more than half, contrasting with the minimal adaptation observed in earlier years. This long-run heat adaptability is seen in both crop yields and farm profits. Heat-induced adjustments in production inputs, practices, technology, and farm consolidation help explain the enhanced adaptability.

Ecosystem services are essential to economic activity, yet their social value is difficult to quantify since markets rarely internalize the externalities they generate. This paper provides causal evidence on the economic value of ecosystem services by studying bees, the primary pollinators in modern agriculture. Assembling comprehensive data on US agriculture and bee colonies, we construct a county-by-year measure of local bee services that combines variation in regional bee supply, crop-specific pollination demand, and local crop structure, and link it to revealed local economic outcomes. To address endogeneity, we develop a novel instrumental-variables strategy that exploits the mass seasonal movements of commercial bees, using machine-learning methods subject to ecological constraints to trace exogenous colony shocks across space. Our IV estimates indicate that the economic value of an additional colony is approximately $5,271, an order of magnitude larger than the observed rental price. The implied aggregate value of US bee colonies exceeds $14 billion annually, highlighting large unpriced benefits in ecosystem service provision and the potential gains from conservation and coordination policies.