The U.S. Environmental Protection Agency released its 29th annual Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHG Inventory), which presents a national-level overview of annual greenhouse gas emissions from 1990 to 2020.
Net U.S. greenhouse gas emissions were 5,222.4 million metric tons of carbon dioxide equivalent in 2020, a nearly 11 percent decrease in emissions from 2019. The sharp decline in emissions from 2019 to 2020 is largely due to the impacts of the coronavirus (COVID-19) pandemic on travel and economic activity. However, the decline also reflects the combined impacts of several factors, including population trends, energy market trends, technological changes including energy efficiency improvements, and the carbon intensity of energy fuel choices.
EPA made adjustments to this reading. EPA added estimates for two important sources of methane: emissions from post-meter uses of natural gas, which includes leak emissions from residential and commercial appliances, industrial facilities and power plants, and natural gas fueled vehicles; and emissions from flooded lands such as hydroelectric and agricultural reservoirs. Additionally, the EPA worked with researchers to include estimates of methane emissions from large anomalous leak events, such as well blow-outs.
The primary driver for the 11 percent decrease in CO2 emissions from fossil fuel combustion. This decrease was primarily due to a 13 percent decrease in transportation emissions driven by decreased demand due to the ongoing COVID-19 pandemic. Electric power sector emissions also decreased 10 percent, reflecting both a slight decrease in demand from the COVID-19 pandemic and a continued shift from coal to less carbon intensive natural gas and renewables.
The GHG Inventory covers seven key greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride. In addition to tracking U.S. greenhouse gas emissions, the Inventory also calculates carbon dioxide that is removed from the atmosphere through the uptake of carbon in forests and other vegetation.