There is no shortage of information on the problem of global warming due to increased CO2 emissions into the atmosphere. A good overview can be found at the NASA website here. It may seem obvious, but it is worth re-stating that climate change is a global phenomenon typically measured in terms of global averages. Less attention has been paid to changes in the climate for smaller geographic areas, like the U.S. Corn Belt. While the Corn Belt looms large in global grain production, it represents only 0.3 percent of the total surface area of the world. Even if one restricts attention to land area, the Corn Belt only represents 0.4 percent of total land mass around the world. Given that the Corn Belt is such a tiny sliver of global surface area, climatic trends could certainly vary substantially from broad global averages. The purpose of this article is to examine trends in monthly temperature and precipitation during the growing season for the U.S. Corn Belt. Two sample periods will be considered in the analysis. The first is 1980 through 2023, the same as that used in the estimation of a crop weather model of the U.S. average corn yield in several recent farmdoc daily articles (October 9, 2023; April 8, 2024; April 29, 2024; May 6, 2024). The second is 1895 through 2023, which is the longest series of monthly observations available from the U.S. National Weather Service.
