United States
Environmental Protection
^1 M % Agency
430-K-20-001
Data Highlights
Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018
About the Greenhouse Gas Inventory
EPA's annual report, the Inventory of U.S. Greenhouse Gas Emissions and Sinks (the Inventory), provides a
comprehensive accounting of U.S. greenhouse gas emissions and sinks by source, economic sector, and greenhouse
gas going back to 1990. This technical overview summarizes the latest information on U.S. anthropogenic greenhouse
gas emission trends from 1990 through 2018. The estimates presented are calculated using methodologies consistent
with those recommended in the 2006 Intergovernmental Panel on Climate Change (IPCC) Guidelines for National
Greenhouse Gas Inventories (IPCC 2006).
In preparing the annual Inventory, EPA collaborates with hundreds of experts representing more than a dozen U.S.
government agencies, academic institutions, industry associations, consultants, and environmental organizations. EPA
also collects greenhouse gas emission data from individual facilities and suppliers of certain fossil fuels and industrial
gases through its Greenhouse Gas Reporting Program (GHGRP). The GHGRP does not provide full coverage of total
annual U.S. greenhouse emissions and sinks (e.g., the GHGRP excludes emissions from the agricultural, land use, and
forestry sectors), but it is an important input to the calculations of national-level emissions in the Inventory.
Highlights of Recent Trends in Emissions and Sinks
GHG emissions show long-term decline since 2005, with annual variation
In 2018, total gross U.S. greenhouse gas emissions were 6,677 million metric tons of carbon dioxide equivalent (MMT
CO2 Eq.). Net emissions (including sinks) were 5,903 MMT CO2 Eq. From 2005 to 2018, net emissions declined 10
percent, reflecting long-term trends in many factors including population, economic growth, energy markets, technological
changes including energy efficiency, and energy fuel choices. The decline in recent years is due to an increasing shift to
use of less CCte-intensive natural gas for generating electricity and a rapid increase in the use of renewable energy in the
electric power sector. Between 2017 and 2018, greenhouse gas emissions increased 3 percent due to multiple factors,
including increased energy use from greater heating and cooling needs due to a colder winter and hotter summer in 2018
compared to 2017. Since 1990, net emissions have increased 6 percent.
Total U.S. Greenhouse Gas Emissions by Gas
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More about Carbon Dioxide
CO2 is the primary greenhouse gas contributing to total U.S. emissions, accounting for 81 percent of the total in 2018.
Total CO2 emissions increased 3 percent between 2017 and 2018. In 2018, fossil fuel combustion (e.g., for electric power
generation) accounted for nearly 93 percent of CO2 emissions. Changes in CO2 emissions from fossil fuel combustion are
influenced by many of the same long-term and short-term factors already noted above. Fossil fuel combustion CO2
emissions also depend on the type of fuel consumed (e.g., natural gas) and its carbon intensity.
Other sources of U.S. CO2 emissions include non-combustion emissions from industrial processes (e.g., cement
production) and changes in land use. Land use, land-use change and forestry (LULUCF) activities include fluxes of carbon
resulting from land use conversions (e.g., emissions from conversion of forest land to agricultural or urban use) or land
use management practices that remove CO2 from the atmosphere and store it in long-term carbon sinks (e.g., through net
forest growth). The LULUCF sector offset about 12 percent of total gross U.S. emissions in 2018 and is a steady sink
across the 1990 to 2018 time series. Major U.S. sinks include long-term forests and recent conversions of other land uses
to forests.
2018 Sources of Carbon Dioxide (CO2) Emissions
Fossil Fuel Combustion
Non-Energy Use of Fuels
Iron and Steel Production
Cement Production
Petroleum Systems
Natural Gas Systems
Petrochemical Production
Other Industrial Processes
Ammonia Production
Lime Production
Incineration of Waste
Urea Fertilization and Liming
Abandoned Oil and Gas Wells
Net Carbon Stock Change from LULUCF
5,031
C02 as a Portion of
All Emissions
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More about Methane
CH4 accounted for nearly 10 percent of
emissions and has decreased 7 percent since
2005 and 18 percent since 1990. Emissions
increased by less than 1 percent from 2017 to
2018. Key trends include reduced emissions
from natural gas systems due to decreases in
emissions from distribution, transmission, and
storage; decreases in emissions from landfills
due to increased landfill gas collection and less
decomposable materials discarded in landfills;
and increased emissions from livestock in line
with increasing cattle populations.
2018 Sources of Methane (CH4) Emissions
Enteric Fermentation
Natural Gas Systems
Landfills
Manure Management
Coal Mining
Petroleum Systems
Other Energy
Wastewater Treatment
Rice Cultivation
Stationary Combustion
Other Industrial Processes
Composting
Field Burning of Agricultural Residues
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CH4 as a Portion
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More about Nitrous Oxide
N2O accounted for 7 percent of emissions and
has decreased by less than 1 percent since
1990. Emissions increased by 3 percent from
2017 to 2018. Key trends in N2O emissions are
influenced by changes in emissions from
agricultural soils due to interannual weather
patterns, fertilizer use, and crop production; an
increase of N2O emissions from stationary
combustion; and a decrease in N2O emissions
from mobile combustion due to national
emission control standards and technologies for
on-road vehicles.
2018 Sources of Nitrous Oxide (NjO) Emissions
Agricultural Soil Management
Stationary Combustion
Manure Management
Mobile Combustion
AdipicAcid Production
Nitric Acid Production
Petroleum Systems
Other Industrial Processes
Wastewater Treatment
Composting
Field Burning of Agricultural Residues
Other Energy
NjO as a Portion
of All Emissions
PFCs. SF
and NF
MMT CO
Data Highlights: Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018
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More about Fluorinated Gases
Emissions of fluorinated gases accounted for
3 percent of emissions and have increased
by 24 percent since 2005 and 83 percent
since 1990. Emissions decreased by less
than 1 percent since 2017. Key trends
include a significant increase in MFCs and
PFCs resulting from the substitution of ozone
depleting substances (ODS) as a result of
efforts to phase out CFCs and other ODS in
the U.S., and increases in emissions from the
electronics industry reflecting the competing
influences of industrial growth and the
adoption of emission reduction technologies.
2018 Sources of Fluorinated (HFCs, PFCs, SFe, and NF3) Emissions
168
Substitution of Ozone Depleting
Substances
Electronics Industry
Electrical Transmission and Distribution
HCFC-22 Production
Aluminum Production
Magnesium Production and Processing
HFCs
SFe,
Portion
Emissions
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MMT C02 Eq.
Emissions by Economic Sector
Greenhouse gases are emitted across five economic sectors: transportation, electric power (electricity generation),
residential/commercial (homes and businesses), industry, and agriculture. For more information on trends in the land use,
land use change and forestry sector, see textbox above titled More about Carbon Dioxide.
U.S. Greenhouse Gas Emissions Allocated to Economic Sectors*
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2,000
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Transportation Sector
Transportation activities are the largest source of emissions, accounting for 28 percent of total U.S. greenhouse gas
emissions in 2018, and have increased by 2 percent since 2017. From 1990 to 2018, transportation emissions from fossil
fuel combustion rose by 21 percent 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 percent from 1990 to 2018; VMT
by medium- and heavy-duty trucks increased 113 percent 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 percent of CO2 emissions from
transportation fossil fuel combustion and medium- and heavy-duty trucks and buses represented 25 percent. Petroleum-
based products supplied 95 percent of the energy used for transportation, with 57 percent 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 percent of petroleum-based energy used for transportation
was supplied by natural gas, residual fuel, aviation gasoline, and liquefied petroleum gases.
Data Highlights: Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018
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Fuels Used in Transportation Sector, Onroad VMT, and Total Sector CO2 Emissions
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Electric Power Sector
The electric power sector accounted for 27 percent of total U.S. greenhouse gas emissions in 2018. While emissions from
the electric power sector have decreased by approximately 4 percent since 1990, the carbon intensity of the electric
power sector, in terms of emissions (CO2 Eq.) per QBtu input, has significantly decreased-by 13 percent-during that
same timeframe. This decoupling of electric power generation and the resulting CO2 emissions is shown below.
Electric Power Generation and Emissions
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Trends in CO2 emissions from fossil fuel combustion have been strongly influenced by the electric power sector, which
historically has accounted for the largest share of these emissions. The types of fuel consumed to produce electricity
have changed in recent years. Total electric power generation increased by 3 percent from 2017 to 2018. However, CO2
emissions only increased 1 percent from 2017 to 2018 due to increasing electric power generation from natural gas and
renewables and decreasing generation from coal. Carbon dioxide emissions from coal consumption for electric power
generation decreased by 42 percent since 2005. The decrease in coal-powered electricity generation and increase in
natural gas and renewable electricity generation have contributed to a 27 percent decrease in overall CO2 emissions from
electric power generation from 2005 to 2018.
Commercial and Residential Sectors
The commercial and residential sectors accounted for 7 and 6 percent total U.S. greenhouse gas emissions in 2018,
respectively. Emissions from the commercial and residential sectors have increased since 1990 and short-term trends are
often correlated with seasonal fluctuations in energy use caused by weather conditions. Emissions from natural gas
consumption in the residential and commercial sectors increased by 13 percent and 11 percent from 2017 to 2018,
respectively. This trend can largely be attributed to a 12 percent increase in heating degree days, which led to an
increased demand for heating fuel in these sectors.
Data Highlights: Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018
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Fuels Used in Residential and Commercial Sectors, Heating and Cooling Degree Days, and Total Sector
CO2 Emissions
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References
EPA (2020) Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018. Office of Atmospheric Programs, U.S.
Environmental Protection Agency (EPA Publication No. 430-R-20-002). Available online at:
https://www.epa.aov/ahaeinissions/inventorv-us-areenhouse-aas-emissions-and-sinks-1990-2018
U.S. Energy Information Administration (EIA) (2020a) March 2020 Monthly Energy Review. Available online at:
https://www.eia.aov/totalenerav/data/monthlv/pdf/mer.pdf
U.S. EIA (2020b) Short-Term Energy Outlook (STEO): March 2020. Available online at: https://www.eia.aov/outlooks/steo/
EPA (2019) Clean Air Markets: Power Plant Emission Trends. Available online at: https://www.epa.gov/airmarkets/power-
plant-emission-trends
For More Information
Additional resources and tools with more information and data related to the U.S. Greenhouse Gas Inventory are
available at: https://www.epa.aov/ahaemissions/inventorv-us-areenhouse-aas-emissions-and-sinks.
Fast Facts on the National-Level U.S. Greenhouse Gas Inventory and U.S. Transportation sector provide a quick
look at trends and an overview of findings
„Fast
racts
U.S. Transportation Sector
Greenhouse Gas Emissions
The Greenhouse Gas Inventory Data Explorer
allows users to visualize the data underlying U.S.
Inventory estimates
The full Inventory of U.S. Greenhouse Gas
Emissions and Sinks: 1990-2018 report here
provides access to in-depth information on data
sources and methodologies
Greenhouse Gas Inventory Data Explorer
Inventory of
U.S. Greenhouse Gas
Emissions and Sinks
¦ ll'liSJiH:!
Download CSVs of the Inventory report
tables for your own use
Data Highlights: Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018
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