CBO’s Benchmark Projection of Greenhouse Gas Emissions

Greenhouse gases (GHGs) accumulate in the atmosphere when fossil fuels are burned to produce energy; they also accumulate as a result of industrial processes and activities such as deforestation and agriculture. GHGs, which include carbon dioxide, methane, nitrous oxide, and other (mainly fluorinated) gases, vary in their contributions to atmospheric warming: They remain in the atmosphere for different lengths of time and cause different amounts of warming while they are present. So that GHGs can be compared on a common basis, emissions are often measured in carbon dioxide equivalent units (CO₂e), or the amount of CO₂ that would cause the same amount of warming over a given period (typically a century).

The Congressional Budget Office maintains a 10-year benchmark projection of annual GHG emissions to estimate the effects that certain GHG emissions policies, such as setting a price on those emissions, would have on the federal budget. This report presents CBO’s most recent projection of GHG emissions. According to that projection, GHG emissions in the United States, measured in CO₂e, decline by about 8 percent from 2025 to 2034. That decline is driven by a projected decrease of 15 percent in energy-related emissions of CO₂, partially offset by an increase of 9 percent in other, non-energy-­related emissions.