The latest EPA report relating to U.S. GHGs is in for 2013,
so this seems like a good time to review that data and see what else we can
say. EPA’s 2013 report compiles data
through 2011, but there is other information that can help us see what probably
occurred in 2012.
The 2013 EPA report indicates that total U.S. GHGs in 2011
fell by 1.6 percent relative to 2010.
These emissions were 6.9 percent lower than total U.S. emissions in
2005. An EPA graph showing U.S.
emissions since 1990 is reproduced as Figure 1 below. As can be seen there, the U.S. total has been
trending downward since about 2006.
Figure 1. Total U.S. GHG
Emissions
Why has this been happening?
For one, the U.S. economy was in recession during some of that time, resulting
in a contraction of economic activity and thus a reduced demand for
energy. For another, large new supplies
of natural gas have been coming onto the market, leading to displacement of
coal among power producers. Gas
consumption has approximately half the GHG content of coal on an
energy-equivalent basis.
EPA compiles data for all forms of GHGs, not just those from
the burning of fossil fuels. However,
carbon dioxide is by far the largest single contributor to the annual total,
making up approximately 85 percent.
Therefore, if we know what happened to GHGs from fossil fuel consumption
in 2012, we’ll have a pretty good idea of what happened to the total.
The Energy Information Administration (EIA) compiles data
relating to fossil fuel consumption. Its
numbers for 2011 and 2012 are shown in Table 1.
As can be seen there, coal and oil consumption dropped in 2012 while
natural gas consumption rose. These
numbers suggest that U.S. CO2 emissions probably dropped in
2012. This is confirmed by EIA. According to that source, total U.S. CO2
emissions from fossil fuels fell from 5498 million metric tons (mmt) in 2011 to
5288 mmt in 2012, a decrease of 3.8 percent.
While we do not know the behavior of other U.S. GHGs in 2012, it seems
likely that the overall 2012 number, when it is published in 2014, will show
another decrease.
Table 1.
U.S. Fossil Fuel Consumption in 2011 and 2012 (quadrillion BTUs)
|
|||
Coal
|
Oil
|
Natural Gas
|
|
2011
|
19.66
|
35.46
|
24.86
|
2012
|
17.37
|
34.69
|
25.95
|
Up to a point, this is good news. It appears that increased fuel economy in the
nation’s vehicle fleet in 2012 probably accounts for much of the decrease in oil-related
emissions, and substitution of natural gas and renewables for coal in the power
sector likely drove down emissions there.
However, some of the coal not burned in the U.S. was exported elsewhere,
where it contributed to other country GHGs.
Whether those GHGs would have been as high without the U.S. coal is a
complicated question, too much so to get into here.
Summarizing, U.S. GHGs have been trending downwards, at
least through 2012. It’s too early to
say much about 2013, but the drivers of reduced emissions during the past
couple of years remain in place. Still,
more rapid economic growth probably would result in greater use of energy and
more GHGs. Thus, recent annual declines
in U.S. GHGs may slow or even reverse. In
other words, if we want to see the recent trend continue, we’ll probably have
to take collective action at some point to make it happen.
