Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: March 12, 2010
Publication Date: September 10, 2010
Citation: Hatfield, J.L. 2010. Climate impacts on agriculture in the United States: The value of past observations. Chapter 10. In: Hillel, D., Rosenzwieg, C., editors. Handbook of Climate Change and Agroecosystems: Impact, Adaptation and Mitigation. London, UK: Imperial College Press. p. 239-253. Technical Abstract: Climate impacts on agriculture cause variations in crop yields and lead to lack of stability in grain production. This will become more critical as the world population continues to increase and demands more food. There have been many studies that have shown the impact of climate on agricultural production and defined specific responses to temperature or rainfall but few regional scale studies or comparisons among regions of a country. This study evaluated the historical trends in corn, soybean, and wheat yields across Indiana, Illinois, Iowa, Kansas, South Dakota, and Texas relative to weather responses. In each of these states, the maximum yields in the yield record were isolated to define a maximum yield relationship as a function of time and then used to determine the deviation of each year from the expected maximum yield. This created a yield record that had a range of deviations over time which was then related to monthly average temperature and precipitation for each state. The yield deviations showed that seasonal weather patterns are the dominant factor causing yield deviations from the potential maximum. Frequency distribution of yields in each state revealed that the deviations from maximum varied over the years and the impact of weather variation is as large at present as it was in the past regardless of the improved genetic and management practices. Understanding the impacts of climate on crops will provide a direction for future efforts to increase the resilience of crops to weather and potential adaptation strategies to reduce the impacts of climate on production.