Climate change and agriculture in the United States

Climate change poses unprecedented challenges to U.S. agriculture because of the sensitivity of agricultural productivity and costs to changing climate conditions.[1]

USDA research indicates that "climate change is likely to drive down yields for some crops, harm milk production, and lead to a drop in nutrient density for key crops like rice and wheat."[2][3]

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.[1]

The US Global Change Research Program (2009) assessed the literature on the impacts of climate change on agriculture in the United States, finding that many crops will benefit from increased atmospheric CO
2 concentrations and low levels of warming, but that higher levels of warming will negatively affect growth and yields; that extreme weather events will likely reduce crop yields; that weeds, diseases and insect pests will benefit from warming, and will require additional pest and weed control; and that increasing CO
2 concentrations will reduce the land's ability to supply adequate livestock feed, while increased heat, disease, and weather extremes will likely reduce livestock productivity.[4]

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.[1]

Livestock and crop production systems

Livestock production systems are vulnerable to temperature stresses. An animal’s ability to adjust its metabolic rate to cope with temperature extremes can lead to reduced productivity and in extreme cases death. Prolonged exposure to extreme temperatures will also further increase production costs and pro-ductivity losses associated with all animal products, e.g., meat, eggs, and milk.[1]

Projections for crops and livestock production systems reveal that climate change effects over the next 25 years will be mixed. The continued degree of change in the climate by midcentury and beyond is expected to have overall detrimental effects on most crops and livestock. Climate change will exacerbate current biotic stresses on agricultural plants and animals.[1]

Weeds, diseases, pests and pollinators

Changing pressures associated with weeds, diseases, and insect pests, together with potential changes in timing and coincidence of pollinator lifecycles, will affect growth and yields. The potential magnitude of these effects is not yet well understood. For example, while some pest insects will thrive under increasing air temperatures, warming temperatures may force others out of their current geographical ranges. Several weeds have shown a greater response to carbon dioxide relative to crops; understanding these physiological and genetic responses may help guide future enhancements to weed management.[1]

Soil and water impacts

Agriculture is dependent on a wide range of ecosystem processes that support productivity including maintenance of soil quality and regulation of water quality and quantity. Multiple stressors, including climate change, increasingly compromise the ability of ecosystems to provide these services.[1]

Key near-term climate change effects on agricultural soil and water resources include the potential for increased soil erosion through extreme precipitation events, as well as regional and seasonal changes in the availability of water resources for both rain-fed and irrigated agriculture.[1]

Extreme weather

The predicted higher incidence of extreme weather events will have an increasing influence on agricultural productivity. Extremes matter because agricultural productivity is driven largely by environmental conditions during critical threshold periods of crop and livestock development. Improved assessment of climate change effects on agricultural productivity requires greater integration of extreme events into crop and economic models.[1]

Human impact on agricultural vulnerability

The vulnerability of agriculture to climatic change is strongly dependent on the responses taken by humans to moderate the effects of climate change.[1]

Role of the US Department of Agriculture

A "USDA Science Blueprint" released in February 2020 focuses on areas from "soil health to weather impacts on agriculture to data collection, and specifically mentions climate change."

A leader at the Union of Concerned Scientists commented, "It is refreshing to see the USDA under Secretary Perdue—who has previously denied the reality of climate change—acknowledging that agriculture is a contributor to climate change, can also be part of the solution, and must adapt in any case."[5]

Concerns remain regarding the cuts to USDA's scientific funding, and the loss of scientific capacity resulting from the decision to move the Economic Research Service (ERS)  and the National Institute of Food and Agriculture (NIFA) away from the Washington DC region.[5]

It is unclear how the plan will impact efforts to involve farmers in the process of carbon sequestration.[5]

References
  1. USDA Agricultural Research Service, Climate Change Program Office (2013). "Climate Change and Agriculture in the United States: Effects and Adaptation" (PDF). United States Department of Agriculture. USDA Technical Bulletin 1935. pp. 1–2. Retrieved 2019-10-15.
  2. Evich, Helena Bottemiller (2019-09-19). "Senate Democrats release list of climate studies buried by Trump administration". POLITICO. Retrieved 2019-10-25.
  3. US Senate Committee on Agriculture, Nutrition and Forestry. "Peer-Reviewed Research on Climate Change by USDA Authors, January 2017-August 2019". Retrieved 2019-10-25.
  4. USGCRP (2009). "Agriculture". In Karl, T.R.; Melillo. J.; Peterson, T.; Hassol, S.J. (eds.). Global Climate Change Impacts in the United States. Cambridge University Press. ISBN 978-0-521-14407-0.
  5. Gustin, Georgina (2020-02-08). "Is Trump's USDA Ready to Address Climate Change? There are Hopeful Signs". InsideClimate News. Retrieved 2020-02-08.

 This article incorporates public domain material from the United States Department of Agriculture document: USDA Agricultural Research Service, Climate Change Program Office. "Climate Change and Agriculture in the United States: Effects and Adaptation" (PDF). Retrieved 2019-10-15.

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