April 14, 2011

Biggest Drop in U.S. Greenhouse Gas Emissions

In 2009, greenhouse gas emissions in the U.S. experienced their biggest drop since the U.S. Energy Information Administration began tracking them during the 1990-2009 timeframe.

The EIA’s latest numbers on greenhouse gas emissions can be found in their just released report “Emissions of Greenhouse Gases in the United States 2009.”

The EIA starts out with this summary:

Total U.S. anthropogenic (human-caused) greenhouse gas emissions in 2009 were 5.8 percent below the 2008 total. The decline in total emissions—from 6,983 million metric tons carbon dioxide equivalent (MMTCO2e) in 2008 to 6,576 MMTCO2e in 2009—was the largest since emissions have been tracked over the 1990-2009 time frame. It was largely the result of a 419-MMTCO2e drop in carbon dioxide (CO2) emissions (7.1 percent).

Why, pray tell, did such a large emission drop occur in 2009? According to the EIA:

The decrease in U.S. CO2 emissions in 2009 resulted primarily from three factors: an economy in recession, a particularly hard-hit energy-intensive industries sector, and a large drop in the price of natural gas that caused fuel switching away from coal to natural gas in the electric power sector.

In Figure 1 we show the history of carbon dioxide emissions—primary among the greenhouse gases—in the U.S. from 1990-2009. We also include the emissions history from China, for comparative purposes.

Figure 1. Annual carbon dioxide emissions from the United States (blue) and China (red), 1990-2009 (data source, EIA).

Notice several things:

• U.S. CO2 emissions in 2009 were the lowest since 1995.

• The trend in U.S. carbon dioxide emissions has been downward since 1999.

• China’s CO2 emissions have increased by about 175% since 1999.

• In 2009, China’s emissions were 42% greater than ours.

The trend in China’s CO2 emissions since 1999 is 508mmtCO2/yr—a value equal to about 1/10th of the U.S. total annual emissions.

Think about this for a minute.

The plans that are kicked around in Congress from time to time (although certainly less so this year), typically call for a reduction in U.S. CO2 emissions roughly on this schedule: 20% in 2020, 40% in 2030, and 80% by 2050.

Now, consider that currently China adds to its total CO2 emissions an equivalent of 10% of the U.S. baseline emissions each year. So, if everything went according to plan, as the U.S. worked to reduce its emissions by 20% by 2020, China meanwhile will have increased their total by about quadruple that amount. And the numbers get worse from there.

So you can see the inherent silliness in using “climate change” as a reason for pushing for reductions in U.S. carbon dioxide emissions.

In fact, U.S. politicians who are thinking that their first responsibility should be towards improving the situation for Americans here and now, ought to be seeking out ways to get the U.S. CO2 emissions heading upwards again.

We say this because two the three reasons given by the EIA for the recent drop in U.S. CO2 emissions have to do with the poor economic times. Turn around the economy and you will turn around emissions.

What about the third reason—increased electricity production from natural gas?

Burning natural gas does actually reduce CO2 emissions per unit energy produced, but, in terms keeping the trend of total U.S. CO2 emissions in the negative territory, this effect is probably trumped by the hard economy. Further, there is a hot-off-the-presses new study that suggests that the carbon dioxide savings from natural gas acquired through hydraulic fracturing (a fast-growing technique to recover loads of natural gas domestically) may actually be (more than) offset by the by-product release of methane during the extraction process (Howarth et al., 2011). So the climate benefits of switching to natural gas (from coal) to produce electricity are perhaps not as great as they are being touted. We’re sure we’ll be hearing more about this—in fact, stay tuned to these pages because we are working through the Howarth et al. article and will post our findings soon!

So, what’s in store for 2010? Probably more of the same—that is, a relatively low level of carbon dioxide emission from the U.S.—as the circumstances that led to the low value in 2009 were pretty much the same as the situation in 2010.

Hopefully, for all our sakes, the trend won’t stay negative for too much longer—at least not for the current reasons.


Energy Information Administration, 2011. Emissions of Greenhouse Gases in the United States, 2009. http://www.eia.gov/environment/emissions/ghg_report/

Energy Information Administration, 2011. International Energy Statistics, http://www.eia.gov/cfapps/ipdbproject/IEDIndex3.cfm?tid=90&pid=44&aid=8

Howarth, R.W., R. Santoro, and A. Ingraffea, 2011. Methane and the greenhouse-gas footprint of natural gas from shale formations. Climatic Change Letters, in press.

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