The 2020 edition of US Environmental Protection Agency’s (EPA) comprehensive annual report on nationwide greenhouse gas (GHG) emissions shows that emissions increased from 2017 to 2018 by 3.1% (after accounting for sequestration from the land sector).

In 2018, US greenhouse gas emissions totaled 6,677 million metric tons of carbon dioxide equivalents, or 5,903 million metric tons of carbon dioxide equivalents after accounting for sequestration from the land sector.

This increase was largely driven by an increase in emissions from fossil fuel combustion, which was a result of multiple factors, including more electricity use greater due to greater heating and cooling needs due to a colder winter and hotter summer in 2018 in comparison to 2017.

Since 2005, national greenhouse gas emissions have fallen by 10%, and power sector emissions have fallen by 27% even as the economy grew by 25%.

While the current Inventory does not include 2019, preliminary energy data available now for 2019 from EIA projects that fossil fuel-CO₂ emissions decreased by approximately 3% from 2018 to 2019.

The gases covered by this inventory include: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride and nitrogen trifluoride. The inventory also calculates carbon dioxide emissions that are removed from the atmosphere by sinks—e.g., through the uptake of carbon and storage in forests, vegetation and soils.

Transportation sector. Transportation activities are the largest source of emissions, accounting for 28% of total US greenhouse gas emissions in 2018, and have increased by 2% since 2017.

From 1990 to 2018, transportation emissions from fossil fuel combustion rose by 21% due in large part to increased demand for travel. The number of vehicle miles traveled (VMT) by light-duty vehicles (i.e., passenger cars and light-duty trucks) increased by 46% from 1990 to 2018; VMT by medium- and heavy-duty trucks increased 113% over the same period.

While an increased demand for travel has led to increasing CO₂ emissions since 1990, improvements in average new vehicle fuel economy since 2005 has slowed the rate of increase of CO₂ emissions. In 2018, light-duty vehicles represented 58% of CO₂ emissions from transportation fossil fuel combustion and medium- and heavy-duty trucks and buses represented 25%.

Petroleum-based products supplied 95% of the energy used for transportation, with 57% from gasoline consumption in automobiles and other highway vehicles. Diesel fuel for freight trucks and jet fuel for aircraft accounted for 24 and 13 percent of fuel consumption, respectively. The remaining 6% of petroleum-based energy used for transportation was supplied by natural gas, residual fuel, aviation gasoline, and liquefied petroleum gases.

This annual report is prepared by EPA in collaboration with numerous experts from other federal agencies including the US Department of Energy’s Energy Information Administration, US Department of Defense and US Department of Agriculture; state government authorities; research and academic institutions; and industry associations.