USDA ERS - Climate Change

ERS conducts research on a range of climate change issues related to agriculture, including:

See the sidebar links to ERS climate-related resources; selected publications are highlighted below.

The Fifth U.S. National Climate Assessment (NCA5) surveyed recent scientific literature on climate change, impacts, adaptation, and mitigation. Quoting NCA5, these are major findings:

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: 1990–2022, April 2024). 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 (see the most recent USDA report, 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 10.5 percent of U.S. greenhouse gas emissions in 2022. Of the 10.5 percent, electricity-related CO2 emissions accounted for 0.5 percent, and CO2 from on-farm energy use accounted for 0.8 percent. Agricultural practices that emit nitrous oxide include nitrogen fertilizer application and manure management. Major sources of agricultural methane emissions include enteric fermentation, manure management, and rice cultivation.

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 663.6 million metric tons of carbon-dioxide equivalent in 2022: 46.6 percent as nitrous oxide, 41.7 percent as methane, and 11.6 percent as carbon dioxide (EPA 2024).

The EPA Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2022 (EPA 2024) 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 human 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 2024). The LULUCF estimated net sink is 854.2 million metric tons of carbon-dioxide equivalent in 2022.

All dimensions of food security—availability, accessibility, utilization (or usability), and stability—are expected to be affected by climate change through long-term changes in average climatic conditions (e.g., annual precipitation and temperature), as well as increases in climate variability and the frequency, magnitude, and duration of climate extremes (NCA5, Ch. 11, page 11-14). 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:

There are many opportunities to decrease greenhouse gas emissions of croplands and pasture, including improving soil health, improving nitrogen fertilizer management, increasing the number of trees and other perennials on the landscape, and reducing methane emissions (NCA5, Ch. 32, page 32-20). 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:

Last updated: Thursday, October 17, 2024

For more information, contact: Ron Sands