Attribution of U.S. Crop Yields to Climate Variations and Pollution Damages

The United States is a world leading agricultural producer. Its crops provide food for a major portion of the population around the world. In a changing climate it is critical to understand whether such production is sustainable and how this will affect food supply and security. Climate and air pollution are crucial variables controlling crop growth and productivity. We first compiled and synthesized long-term data records related to crop growth. These include: (1) USDA crop data at the county level; (2) Climate data from the National Climate Data Center; (3) Surface ozone and PM2.5 concentrations from the EPA’s Air Quality System and simulated by the regional CWRF-CMAQ modeling system; and (4) USDA total factor productivity data. These data from different sources contain inconsistencies in quality and spatiotemporal resolution, which must be corrected to produce a reliable, synthesis database for the subsequent attribution analysis. We then conduct an analysis of the database to determine the relative contributions on crop yields from regional climate and air pollution. We use random forest regressions to develop a multivariate model that links crop yields with climate conditions and pollution levels to study relative contributions from each climate variable and their dependent factors. Finally, we analyze when each crop is most vulnerable to air pollution and weather extremes during the growing season. These findings will support our future investigation of the impact climate change may have on agricultural yields.