ERS conducts research on a range of climate change issues related to agriculture, including:
- The impacts of climate change on crop production, livestock production, and land use.
- The implications of climate change for agricultural markets and the cost of government policies/programs
- The potential for agriculture to adapt to changing climate conditions
- The potential within agriculture for mitigation of greenhouse gas emissions
- The role of USDA farm programs under changing climate conditions
- Drought resilience and risk management
See the sidebar links to ERS climate-related resources; selected publications are highlighted below.
The Fourth U.S. National Climate Assessment (NCA4) surveyed recent scientific literature on climate change, impacts, adaptation, and mitigation (NCA4, November 2018). Among the report's findings are:
- Global annually averaged surface air temperature has increased by about 1.8°F (1.0°C) over the last 115 years (1901–2016). This period is now the warmest in the history of modern civilization (NCA4, Vol. 1, p. 10).
- The climate change resulting from human-caused emissions of carbon dioxide will persist for decades to millennia (NCA4, Vol. 2, Ch. 2, Key Message 10).
- Current concentrations of atmospheric greenhouse gases commit the world to further warming, and additional increases in annual average temperature are expected over the next few decades regardless of future greenhouse gas emissions (NCA4, Vol. 2, Ch. 2, Key Message 5).
- Annual precipitation since the beginning of the last century has increased across most of the northern and eastern United States and decreased across much of the southern and western United States. Changes in the seasonal distribution of precipitation are also projected; over the coming century, significant increases are projected in winter and spring over the Northern Great Plains, the Upper Midwest, and the Northeast (NCA4, Vol. 2, Ch. 2, Key Message 6).
- Food and forage production will decline in U.S. regions experiencing increased frequency and duration of drought. Shifting precipitation patterns, when associated with high temperatures, will intensify wildfires that reduce forage on rangelands, accelerate the depletion of water supplies for irrigation, and expand the distribution and incidence of pests and diseases for crops and livestock. Modern breeding approaches and the use of novel genes from crop wild relatives are being employed to develop higher-yielding, stress-tolerant crops (NCA4, Vol. 2, Ch. 10, Key Message 1).
Agricultural Greenhouse Gas Emissions
The U.S. Environmental Protection Agency (EPA) publishes annual estimates of U.S. greenhouse gas emissions, including emissions from agriculture (see Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2020, April 2022 (EPA 2022)). USDA publishes a supplemental greenhouse gas inventory for agriculture less frequently, but it provides further background and regional detail not available in the EPA inventory (U.S. Agriculture and Forestry Greenhouse Gas Inventory: 1990-2018, USDA, Office of the Chief Economist, Technical Bulletin No. 1957, January 2022).
The greenhouse gases with the largest contribution to rising temperature are carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). In estimating total emissions, global warming potentials (GWPs) are used to calculate carbon-dioxide equivalents for methane and nitrous oxide to sum emissions impacts over different gases.
EPA estimates that agriculture accounted for 11.2 percent of U.S. greenhouse gas emissions in 2020. Of the 11.2 percent, electricity-related CO2 emissions accounted for 0.6 percent. Other agricultural emissions include N2O from cropped and grazed soils, CH4 from enteric fermentation and rice cultivation, N2O and CH4 from managed livestock manure, and CO2 from on-farm energy use.
Globally, carbon dioxide emissions are the largest contributor to climate change. However, the emissions profile for agriculture differs from that of the overall economy. U.S. agriculture emitted an estimated 669.5 million metric tons of carbon-dioxide equivalent in 2020: 50.5 percent as nitrous oxide, 37.5 percent as methane, and 12.0 percent as carbon dioxide (EPA 2022).
The EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2020 also includes a land use, land-use change, and forestry (LULUCF) chapter, which provides an estimate of emissions (sources) and removals (sinks) from LULUCF conversions between forest land, cropland, grassland, wetlands, and settlements. Carbon sinks include forest management to increase carbon in forests, harvested wood products, increases in tree carbon stocks in settlements, conversion of agricultural to forest land (afforestation), and crop management practices that increase carbon in agricultural soils (EPA 2022). The LULUCF estimated sink is 758.9 million metric tons of carbon-dioxide equivalent in 2020.
Climate Change Impacts and Agricultural Adaptation
Climate change has the potential to adversely impact agricultural productivity at local and regional scales through alterations in rainfall patterns, more frequent occurrences of climate extremes (including high temperatures or drought), altered patterns of pest pressure, and changes in seasonal and diurnal temperature patterns (NCA4, Vol. 2, Ch. 10, p. 393; NCA4, Vol. 2, Ch. 21, p. 880). These impacts will affect national and international markets; the prices of food, fiber, and energy; agricultural incomes; and the environment. How farmers respond or adapt—possibly mediated by policy and technology changes—will ultimately determine the impact of these altered growing conditions on production, natural resources, and food security. ERS publications that consider climate change and agricultural adaptation include:
- Climate Change and Agricultural Risk Management Into the 21st Century (ERR-266, July 2019). The Federal Government offers subsidized premiums on crop insurance as one method of helping farmers manage risk. The Federal Government’s cost exposure under this program is expected to increase as weather averages and extremes change over the coming decades. Cost estimates would be higher if the analysis did not account for adaptation to climate change.
- Development, Adoption, and Management of Drought-Tolerant Corn in the United States (EIB-204, January 2019). Introduced in 2011, drought-tolerant corn accounted for 22 percent of total U.S. corn-planted acreage in 2016. Using data from USDA's Agricultural Resource Management Survey, this report documents trends in its development, adoption, and management, examining the role of drought exposure and moisture conservation practices, as well as genetically engineered seed traits, pricing, and irrigation.
- Climate Change, Water Scarcity, and Adaptation in the U.S. Fieldcrop Sector (ERR-201, November 2015). Climate change is projected to adversely impact yields of corn, soybeans, rice, sorghum, cotton, oats, and silage, with some impacts as early as 2020. The potential reallocation of acreage into irrigated production in response to climate change may be constrained by limits on the regional availability of water resources and on declining relative profitability of irrigated production under conditions of heat stress.
- Using Crop Genetic Resources to Help Agriculture Adapt to Climate Change: Economics and Policy (EIB-139, April 2015). Climate change will likely increase demand for more stress-resistant crop varieties. ERS reviews technical, economic, and institutional factors that could determine the extent of crop genetic resource use to find and incorporate adaptive traits.
- Climate Change, Heat Stress, and U.S. Dairy Production (ERR-175, September 2014). In the United States, climate change is likely to increase average daily temperatures and the frequency of heat waves. Dairy cows are particularly sensitive to heat stress, and the dairy sector has been estimated to bear over half of the costs of current heat stress to the livestock industry.
- Agricultural Adaptation to a Changing Climate: Economic and Environmental Implications Vary by U.S. Region (ERR-136, July 2012). Global climate models predict increases over time in average temperature worldwide, with significant impacts on local patterns of temperature and precipitation. Study findings suggest that while impacts are highly sensitive to uncertain climate projections, farmers have considerable flexibility to adapt to changes in local weather, resource conditions, and price signals by adjusting crops, rotations, and production practices.
Agricultural Production and Climate Change Mitigation
Changes in agricultural production could result in reduced greenhouse gas emissions and removal of carbon dioxide from the atmosphere through carbon sequestration. Farm operators can change production practices or land use to increase the carbon stored in soil or vegetation. Other changes in production practices and land use can result in reduced emissions of methane and nitrous oxide. In addition, agriculture can produce biofuels, which can substitute for fossil fuels and reduce greenhouse gas emissions across multiple sectors. These actions are considered forms of climate change mitigation. ERS publications that consider climate change mitigation include:
- Cover Crop Trends, Programs, and Practices in the United States (EIB-222, February 2021). Depending upon the field, soil, climate, and weather, cover crops can result in a variety of on farm benefits: reduced soil erosion and compaction, improved water infiltration and storage within the soil profile, greater weed and pest suppression, and better nutrient cycling and soil stability to support machine operations. Cover crops can also provide public environmental benefits: less runoff of sediments and nutrients into waterways, reduced flooding in watersheds, and greater soil carbon sequestration.
- Resource Requirements of Food Demand in the United States (ERR-273, May 2020). Three main factors determine the resource requirements of food demand: population, diet, and technology. This study focused on the use of natural resources in the U.S. food system by examining one of these factors, diet, to illustrate how food choices can affect use of resources.
- Tillage Intensity and Conservation Cropping in the United States (EIB-197, September 2018). Most U.S. farmers prepare their soil for seeding, weed and pest control through tillage-plowing operations that disturb the soil. Tillage practices affect soil health, soil carbon content, water pollution, and farmers' energy and pesticide use, and therefore data on tillage can be valuable for understanding the practice's role in reaching climate and other environmental goals.
- International Trade and Deforestation: Potential Policy Effects via a Global Economic Model (ERR-227, April 2017). This report analyzes patterns of deforestation in select countries to examine which commodities contribute most to tropical deforestation. These forests support biodiverse ecosystems and further benefit the environment through carbon storage.
- The Role of Fossil Fuels in the U.S. Food System and the American Diet (ERR-224, January 2017). Fossil fuels linked to U.S. food consumption produced 13.6 percent of all fossil fuel CO2 emissions economywide in 2007. Many potential diets would meet the 2010 Dietary Guidelines for Americans, each with varying energy requirements.
- Dedicated Energy Crops and Competition for Agricultural Land (ERR-223, January 2017). Crops that are grown strictly for energy use, such as switchgrass in the United States, have received much attention as potential renewable sources for bioelectricity; however, markets do not presently exist for large-scale use of this resource. This study examines three policy scenarios that could create a market for bioelectricity using dedicated energy crops.