The United States Department of Agriculture has released a new report on climate change impacts on U.S. agriculture and the effectiveness of adaptation strategies. Comparing results from four general circulation models, the USDA report predicted changes in U.S. agriculture in a climate change scenario, and in a scenario in which farmers take measures to adapt agricultural practices to climate change.
The model results show that climate change would increase yields in some crops (notably cotton and hay), but yields of corn – the most abundantly produced crop in the U.S. – are projected to decrease, especially in the corn belt of the Midwest. Pests would increase with climate change. In response to these changes, corn prices would rise relative to the baseline scenario, and a corresponding increase in corn acreage drives a slight increase in total U.S. crop acreage. It is unclear if the baseline scenario in the four models took into account the current trend of agricultural abandonment in the U.S., so the greater total crop acreage under the climate change scenario may not reflect overall agricultural expansion so much as reduced abandonment.
The USDA report details some actions that could be taken by farmers to adapt to climate change, and thus to mitigate yield losses by high temperatures and drought. Breeding programs for drought-tolerant crops have had some success, and there is potential for further improvements. More farmers could use crop rotations and no-till practices to manage soil nutrients and erosion. Shifting crop patterns, or where specific crops are grown, could also reduce climate change impacts. The models show that use of adaptation techniques like these would improve crop yields and keep prices from rising. But the modeling in the report predicts that climate change adaptation would cause some crop production to shift into areas with greater water-quality impacts. There would be more erosion and nitrogen pollution in the water on average across the U.S. So while this report finds that adaptation strategies may effectively mitigate climate change impacts to some extent, adaptation itself could result in negative environmental consequences.