Nitrous oxide emissions, predominantly from agricultural soil management practices such as the use of nitrogen as a fertilizer, decreased by 3 percent.
Methane emissions decreased by 16 percent, as reduced emissions from landfills, coal mines, and natural gas systems more than offset increases in emissions from activities such as livestock production.Emissions of carbon dioxide, the primary greenhouse gas emitted by human activities, decreased by 2 percent.For the United States, during the period from 1990 to 2021 (see Figure 1):.Emissions increased from 2020 to 2021 by 5.2 percent, driven largely by an increase in carbon dioxide emissions from fossil fuel combustion due to economic activity rebounding after the height of the COVID-19 pandemic (see Figure 1). The sharp decline in emissions from 2019 to 2020 was largely due to the impacts of the coronavirus (COVID-19) pandemic on travel and economic activity. This total represents a 2.3 percent decrease since 1990, down from a high of 15.8 percent above 1990 levels in 2007. greenhouse gas emissions totaled 6,340 million metric tons (14.0 trillion pounds) of carbon dioxide equivalents.
