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U.S. Greenhouse
Gas Emissions
What
Specific Kinds of Greenhouse Gases Does the United States Emit?
Seven
kinds of greenhouse gases are emitted by the United States.
- Carbon
dioxide (CO2)
- Methane
(CH4)
- Nitrous
oxide (N2O)
- High-GWP
gases, which are:
- Hydrofluorocarbons
(HFCs)
- Perfluorocarbons
(PFCs)
- Sulfur
hexafluoride (SF6)
- Water
vapor
(H2O)
- Natural
gas–accounting for 1.2 billion metric tons (20%)
The primary natural processes that release CO2
into the atmosphere (sources) and that remove CO2
from the atmosphere (sinks) are:
- Animal and plant respiration, by which oxygen and nutrients are
converted into CO2 and energy, and
plant photosynthesis by which CO2
is removed from the atmosphere and stored as carbon in plant
biomass;
- Ocean-atmosphere exchange, in which the oceans absorb and
release CO2 at the sea surface; and
- Volcanic eruptions, which release carbon from rocks deep in the
Earth’s crust (this source is very small).
U.S.
Greenhouse Gas Emissions by Gas
Annual Percent Change in U.S.
Greenhouse Gas Emissions
Cumulative Change in
Annual U.S. Greenhouse Gas Emissions Relative to 1990
2009 U.S.
Greenhouse Gas Inventory Report
Greenhouse gas inventory is an accounting of the amount of greenhouse
gases emitted to or removed from the atmosphere over a specific period of
time (e.g., one year). A greenhouse gas inventory also provides
information on the activities that cause emissions and removals, as well
as background on the methods used to make the calculations. Policy makers
use greenhouse gas inventories to track emission trends, develop
strategies and policies and assess progress. Scientists use greenhouse gas
inventories as inputs to atmospheric and economic models.
2009
U.S. Greenhouse Gas Inventory Report
Credit: EPA, EIA
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