Current Benefits of Wildfire Smoke for Yields in the US Midwest May Dissipate by 2050

Wildfires throughout western North America produce smoke plumes that can stretch across theagricultural regions of the American Midwest. Climate change is likely to increase the number and size of these fires andsubsequent smoke plumes. These smoke plumes change direct, diffuse, and total sunlight during the crop growing seasonand consequently influence yields of both corn and soybeans. The analysis in this paper uses a twelve-year panel ofcounty-level yields from all counties east of the 100th meridian combined with measures of exposure to smoke plumesof low and high density during the growing season. It shows that low-density plumes enhance yields, likely by increasingin the fraction of diffuse light, while high-density plumes decrease yields. Because there are more low-density plumestoday, the net effect is a slight increase in yields on average. As climate change makes wildfires larger and morefrequent, the overall impact of smoke on yields is expected to be substantially more negative.