Published on December 7th, 2012 | by Zachary Shahan5
The Myth Of U.S. Carbon Dioxide Emissions Reductions
December 7th, 2012 by Zachary Shahan
This is an excellent, insightful piece by Kevin Matthews, Editor-in-Chief of Architecture Week (reposted from Climate Progress). Though, heads up, it’s also a bit depressing (especially for those of us who were quite happy to see news of the US CO2 emissions drop mentioned below). Not much to preface it with, just read on….
by Kevin Matthews
A person — a public figure, member of the media, maybe even an international climate negotiator — could be confused about U.S. carbon dioxide emissions.
In August, 2012, the Associated Press reported this:
In a surprising turnaround, the amount of carbon dioxide being released into the atmosphere in the U.S. has fallen dramatically to its lowest level in 20 years, and government officials say the biggest reason is that cheap and plentiful natural gas has led many power plant operators to switch from dirtier-burning coal.”
Since August, the misleading meme of shrinking U.S. greenhouse gas emissions has been picked up and carried forward by a variety of respected sources. As recently as November 26, for instance, the Guardian reported on how the findings were influencing climate negotiations:
Greenhouse gas emissions from the US have fallen sharply in recent years, owing to the replacement of coal-fired power generation by gas in the US, following its widespread adoption of shale gas.
Jonathan Pershing, a senior negotiator for the US, said: “Those who don’t know what the US is doing may not be informed of the scale and extent of the effort, but it’s enormous.”
Given these claims, you’d think that there was solid information that U.S. greenhouse gas emissions have dropped. But the real story is somewhat different.
Back in August, the U.S. Energy Information Agency (EIA), part of the U.S. Department of Energy (DOE) that collects and reports certain energy-related data, posted an article centered on this graph:
That graph is labeled obscurely, but with partial accuracy, as showing U.S. “carbon dioxide emissions from energy demand.”
That’s the same as “carbon dioxide emissions from energy use” or “carbon dioxide emissions from energy consumption,” which is primary data collected by the EIA. It’s relatively easy to track in real time, since it’s essentially based on adding up the sales figures for coal, oil, and natural gas.
Therein lies the first layer of confusion. The EIA does not include biomass combustion energy, hydroelectric power, or true renewables like wind and solar in its main energy consumption figures. Except for biomass, there is little CO2 associated with the use of these clean energy sources.
So the EIA graph in the article should be labeled as U.S. “carbon dioxide emissions from fossil fuel consumption.” In fact, that’s exactly how the graph is labeled in EIA’s deeper technical reports. According to the most recent official EPA figures, carbon dioxide emissions from fossil fuel consumption represented about 79% of total U.S. greenhouse gas emissions in 2010.
Starting a tally of this U.S. fossil fuel use “grade inflation,” we can use these terms:
(CO2 emissions from fossil fuel use) + (CO2 emissions from all other energy use) = (total CO2 emissions from energy use).
The big headline on the EIA article adds another level of exaggeration. It says “U.S. energy-related CO2 emissions in early 2012 lowest since 1992.” Note the shift from “energy-use” CO2 emissions to “energy-related” CO2 emissions.
The headline is directly wrong because the underlying data does not include CO2 emissions from energy production and distribution such as flaring of natural gas, an increasing element in the U.S. EIA seems to use the this sloppy label regularly.
(CO2 emissions from energy use) + (CO2 emissions from energy production & distribution) = (energy-related CO2 emissions)
The headline also sets people up for another natural error. While CO2 is the biggest greenhouse gas, it’s not the only one. It’s common practice in adding up climate numbers to convert all the differing units of other greenhouse gases into CO2-equivalent values.
It’s tedious to always say “CO2-equivalent greenhouse gas emissions.” And pretty often, people just say “CO2 emissions” when “CO2-equivalent emissions” is what they really mean.
That’s just a little slippage in our language, but it has big implications for the numbers.
(energy-related CO2 emissions) + (non-CO2 energy-related emissions) = (energy-related greenhouse gas emissions)
The biggest energy-related non-CO2 emissions are methane — and that’s huge.
Estimates of energy-related methane emissions are in flux, as traditional industry numbers are being looked at more closely. Current research, in line with a recent NOAA report, suggests under-reporting by the fossil fuel industry may be on the order of 2 percent of natural gas used, suggesting total methane losses on the order of 4%. Since methane is about 21 times more potent as a greenhouse gas than CO2 (in the time frame of a generation), we can multiply (4% methane leakage) x (21 times GHG impact compared to CO2) = 84%. That shows that methane emissions from the natural gas system may have a CO2-equivalent greenhouse gas impact roughly comparable to the GHG impact in CO2 from burning the gas. While the methane emissions may prove to be somewhat smaller, there’s little doubt they are significant.
This is part of the picture described by guest bloggers Shakeb Afsah and Kendyl Salcito in the Climate Progress article “Shale Gas And The Overhyping Of Its CO2 Reductions.”
By leaving out methane, and other things, the EIA data really only describes one specialized slice of emissions. It’s a big slice, but not one to freely generalize from.
Because renewables are missing from the EIA data, which has been widely and inappropriately generalized, it’s all too easy for pundits and reporters to simply compare the coal curve and the natural gas curve against the (baseless) overall conclusion of dropping emissions, and then call out lower natural gas prices as the cause of U.S. progress — thus leaving out the significant growth of renewables. But that’s another story.
As noted above, it’s apparently been easy for analysts and media alike to take the EIA information to the final level of misinformation, trumpeting that CO2 levels have fallen to their lowest levels in 20 years or that greenhouse gas emissions have fallen sharply.
The claim is wrong, because to get to greenhouse gas emissions overall, all the non-energy-related emissions sources also need to also be included. To summarize and complete the equation:
EIA data: (CO2 emissions from fossil fuel use)
+ (CO2 emissions from all other energy use)
+ (CO2 emissions from energy production & distribution)
+ (non-CO2 energy-related emissions)
+ (all non-energy-related greenhouse gas emissions)
= total greenhouse gas emissions
Methane, flaring, and biomass emissions not included in the primary EIA numbers mean those numbers don’t fully reflect energy-related GHG emissions.
According to the official U.S. GHG emissions inventory, the non-energy-related emissions (from agriculture, logging, other land use changes, etc.) represent another ~20 percent of the total, on top of the ~80 percent of GHG emissions that are directly energy-related.
EPA to the Rescue
The EIA used to actually calculate and report its own U.S. total greenhouse gas emissions numbers. That EIA overall GHG inventory was discontinued in 2011, due to mid-year budget cuts, according to an EIA source. However, the agency has never been the source of the official U.S. inventory.
The official U.S. greenhouse gas emissions inventory has been produced for many years by the EPA, following detailed international reporting protocols. It’s presented to the United Nations every April, in a careful and fairly hard-to-read formal report.
The most recent official EPA inventory, reported in April 2012 and showing total U.S. emissions for 2010, shows our emissions going up that year:
The current EPA inventory report shows total U.S. greenhouse gas emissions for 2010 up 3.2% over 2009 emissions, with an average annual growth rate from 1990 through 2010 of 0.5%. It’s hard to say what increase or decrease the U.S. inventory for 2011 will show, when the EPA releases it in April 2013, or what the inventory for 2012 will show when it comes out in April 2014. Unless someone is prepared to duplicate the EPA’s work, and do it faster, we can expect to wait for those numbers.
U.S. major media and others have been trumpeting a false meme of declining U.S. greenhouse gas emissions, spinning off from EIA data that actually shows a much narrower trend.
While the primary EIA data represents a large, very specific piece of the overall U.S. emission inventory, it’s fundamentally misleading to inflate its importance. Nonetheless, this seems to have been done regularly by the EIA itself, and to an even greater degree by downstream users of EIA information.
In the past, EIA produced an overall emissions inventory. Because energy consumption is easier to collect and report on quickly than other types of emissions, they continue to produce reports including U.S. CO2 emissions from energy use, which the EIA releases at a pace tantalizingly close to real time.
No doubt it’s frustrating to media and officials who love to report on realtime score cards, but the only official U.S. greenhouse gas emission inventory comes from the EPA. It takes a while for all the data to be collected and complied — and impatience is no reason to misrepresent the data available.
In any case, year-to-year ups and downs in U.S. emissions are not very meaningful relative to the scale of the climate mitigation challenge we face together. In the U.S., we need to be planning and faithfully implementing, in every sector of our economy, in every government, agency, and large organization, roughly 5% reductions in total greenhouse gas emissions, every year, year-on-year, for the rest of our lives.
And no blip in annual emissions, whether actual or invented, is going to rescue business-as-usual from this fundamental need for real climate action.
Kevin Matthews is Editor-in-Chief of Architecture Week.
UPDATE Dec 10 (2012) / READER COMMENT:
Re the otherwise excellent article on “The Myth of US Carbon Dioxide Emissions Reductions”:
The EPA’s GWP 100 year equivalent for methane is 25, not 21, and it’s based on a per ton calculation, not a per atom of carbon calculation. So a level of 4% fugitive methane does not have nearly the GWP impact as burning the remaining 96%.
A mole of CO2 weighs 44 and a mole of methane weighs 16. So when you do the calculations using a 25X GWP, it takes around a 10% fugitive methane level before the GWP of that methane exceeds the GWP of the burned remaining 90%.
As to the impact over a “generation”, that’s much harder to calculate, both because of the unclarity as to how many years are in a “generation” (20, 30, 40?), and also because neither the CH4 nor the CO2 disappear completely, although the CO2 takes much longer, and the concentration curve will depend on future emissions levels, among other things. So whether 4% or some other number is the right number for an equivalent impact over a “generation” is not a particularly precise way to discuss this issue.
But the point is there; it just could have been made more accurately.
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