Authored by the USDA.
Climate Change and Agriculture in the United States: Effects and Adaptation
Executive Summary
Key Messages
Increases of atmospheric carbon dioxide (CO2),rising temperatures, and altered precipitation patterns will affect agricultural productivity.Increases in temperature coupled with more variable precipitation will reduce productivity of crops, and these effects will outweigh the benefits of increasing carbon dioxide. Effects will vary among annual and perennial crops, and regions of the United States;however, all production systems will be affected to some degree by climate change. Agricultural systems depend upon reliable water sources, and the pattern and potential magnitude of precipitation changes is not well understood, thus adding considerable uncertainty to assessment efforts.
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Conclusions
The climate of the U.S. has changed during the last 100 years, and the rate of climate change has increased during the last several decades. A large number of observations and simulation experiments clearly show that this long-term change is distinct from the natural variability of climate that the U.S. has always experienced. In most areas of the United States, temperatures have increased. Precipitation changes have been more variable; while some regions have experienced increases, others have seen decreases. The growing season has become longer all across the U.S., and the number of frost days has decreased.
