A Conceptual Model for Assessment of Climate Extremes That Affect Corn Yields
The USA Corn Belt was examined to assess the impacts of observed climate change on corn production for the period 1960–2012. Given a modified definition of a Corn Belt State, 13 states were included in the study. Temperature and precipitation trends during the growing season (April–September) showed the following: a) slight warming of 0.73℉, b) increase in growing season of 9 days, and c) mean precipitation increase of 5.51 cm (2.17 in), which along with technological advancements, support the observed increase of 1.7 bushels per acre per year for the period. A conceptual model assessed the impacts of extreme weather and climate on corn yields in bushels per acre. This model is represented by an Upper Bound (based on technological advancements), and a Lower Bound that is defined as the difference between the mean production and the Upper Bound. All values that fall below the Lower Bound were defined as extremely poor yields that can be attributed to extreme weather and climate events. The model was applied to the entire Corn Belt Region for the period 1960–2012. The years 1983, 1988, 1993, and 2012 were identified as extreme events (which are well-recognized in the agroeconomic community). The benchmark model framework can be extended through the 21st century to monitor the number of extreme events and the magnitude of their departure from the Lower Bound, and it is presented as an instrument for assessing climate change impacts on corn yields.