691N/g, 

Cornell University 

; 

Department of Ecology and Evolutionary Biology 

Statement on EPA Draft Plan Released June 2, 2014 on 

"Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility 

Generating Units" 

RIN 2060-AR33 

by 

Robert W. Howarth, Ph.D. 

The David R. Atkinson Professor of Ecology & Environmental Biology 

Cornell University, Ithaca, NY 14853 USA 

June 7, 2014 

I have carefully read the 645-page Draft Plan. There is much to commend in the Plan's goals to 

reduce carbon dioxide emissions and to promote more production of electricity by renewable sources 

and more efficient end use of electricity. However, the Plan has a fundamental flaw: it addresses only 

carbon dioxide emissions, and not emissions of inethane, another critically important greenhouse gas. 

This failure to consider methane causes the Plan to promote a very poor policy — replacing coal-burning 

power plants with plants run on natural gas (see pages 33-34) — as one of the major four building blocks 

of the Plan. Recent research indicates that the greenhouse gas footprint of generating electricity from 

natural gas can exceed that of coal-fired plants (Alvarez et al. 2012; Howarth et al. 2014 and references 

therein). The Plan should be revised to reflect the importance of inethane and the extent of inethane 

emissions from using natural gas. While phasing out coal is a desirable goal, replacing coal with natural 

gas trades one problem for another, reducing carbon dioxide emissions but increasing methane 

emissions to such an extent as to cause even greater global warming. 

"Methane" is mentioned only five times in the 645 pages. The first time is on page 59, where it 

is stated that EPA could not monetize the consequences of nitrous oxide and methane emissions, and 

that the Plan therefore focuses only on carbon dioxide emissions. The second time is footnote #13 on 

page 59, where it is stated that "although CO 2 is the predominant greenhouse gas released by the power 

sector, electricity generating units also emit small amounts of nitrous oxide and methane...." Note that 

in both the first and second mention of inethane in the Plan, nitrous oxide comes before methane, even 

though methane is far more important in global warming (IPCC 2013). Further note that the Plan seems 

to limit the focus to emissions at electric-power generating plants rather than include full life-cycle 

emissions. The third time is on page 174, where the Plan states "we have also analyzed potential 

upstream net methane emissions impact from natural gas and coal for the impacts analysis. This analysis 

indicated that any net impacts from methane emissions are likely to be small compared to the CO Z 

emissions reduction impacts of shifting power generation from coal-fired steam EGUs to NGCC units." 

And the fourth and fifth times are late in the Plan, where it is mentioned that methane is emitted from 

landfills and where natural gas is defined. 
Early in the Plan (page 19), the focus on carbon dioxide is justified by stating "COZ is the primary 

GHG pollutant, accounting for nearly three-quarters of global GHG emissions 1 and 82 percent of U.S. 

GHG emissions. 2 These statements do not accurately reflect the most recent and best science on this 

topic. Footnote #1 refers to the IPCC (2007) report and is based only on comparing methane emissions 

and carbon dioxide emissions on a 100-year time scale. In the more recent IPCC (2013) synthesis, the 

IPCC explicitly states that "There is no scientific argument for selecting 100 years compared with other 

choices," and that "The choice of time horizon .... depends on the relative weight assigned to the effects 

at different times." Because the short-term dynamics of the climate system are far more responsive to 

methane than to carbon dioxide (UNEP/WMO 2011; Shindell et al. 2012), comparing methane and 

carbon dioxide on shorter time scales is essential if we are to avoid warming the Earth to temperatures 

that greatly increase the risk of tipping points in the climate over the coming 15 to 35 years (see 

Howarth et al. 2014 and references therein). At these shorter time scales, the IPCC (2013) states that 

the global emissions of inethane are actually greater than (slightly, for the 10-year time frame) or 80% of 

(for the 20-year time frame) those of carbon dioxide in terms of their influence on global warming; at 

both of these shorter time scales, carbon dioxide is responsible for less than half of global GHG 

emissions, not three-quarters. 

Similarly, the statement that 82% of US greenhouse gas emissions are due to carbon dioxide 

(referencing footnote #2, which is the EPA greenhouse gas inventory) is highly misleading. This also is 

based solely on comparing methane and carbon dioxide on a 100-year time scale, and further uses 

outdated global warming potentials (from earlier versions of the IPCC, not from IPCC 2013, where the 

global warming potential for methane has been substantially increased). Also, the best available 

evidence indicates that the EPA estimates for methane emissions in the US are much too low (Miller et 

al. 2013; Brandt et al. 2014; Howarth et al. 2014). EPA aggravated this by reducing their methane 

emissions for the natural gas industry by a factor of two in 2013, despite increasing evidence that their 

estimates were already too low (Miller et al. 2013; Brandt et al. 2014; Howarth et al. 2014). The 

Inspector General for the EPA has called for an improved approach by EPA for estimating methane 

emissions from the oil and gas industry (U.S. Environmental Protection Agency Office of Inspector 

Genera12013). 

In addition to ignoring the global-warming consequences of inethane and natural gas, the Plan 

does not adequately consider the public health consequences. The Plan states that "actions taken to 

comply with the proposed guidelines will reduce emissions of CO 2 and other air pollutants, including 

S02, NOx and directly emitted PM2 , 5, from the electric power industry" (page 51). Reducing these 

pollutants — which largely come from combusting coal — is desirable. However, the use of natural gas is 

leading to highly elevated levels of ground-level ozone in many areas as well as elevated concentrations 

of benzene and other toxic and carcinogenic hydrocarbons. The Plan completely ignores these other 

pollution issues. 

A sound government policy on climate simply cannot focus solely on carbon dioxide and ignore 

methane. The number one source of inethane pollution in the US is the natural gas industry (Howarth 

et al. 2012), and the US should take urgent steps to reduce this methane pollution. The Plan will require 

substantial revision using better quality and more recent science to consider both carbon dioxide and 

methane emissions. 

2 
References cited: 

Alvarez RA, Pacala SW, Winebrake JJ, Chameides WL, and Hamburg SP. 2012. Greater focus needed on 

methane leakage from natural gas infrastructure. Proceedings of the National Academy of 

Sciences, doi 10.1073/pnas.1202407109. 

Brandt AF, Heath GA, Kort EA, O'Sullivan FO, Petron G, Jordaan SM, Tans P, Wilcox J., Gopstein AM, 

Arent D, Wofsy S, Brown NJ, Bradley R, Stucky GD, Eardley D, and Harriss R. 2014. Methane 

leaks from North American natural gas systems. Science 343: 733-735. 

Howarth RW. 2014. A bridge to nowhere: Methane emissions and the greenhouse gas footprint of 

natural gas. Energy Science & Engineering, doi 10.1002/ese3.35 

http://onlineli bra ry.wiley.com/doi/10.1002/ese3.35/fu II 

Howarth, R. W., D. Shindell, R. Santoro, A. Ingraffea, N. Phillips, and A. Townsend-Small. 2012. Methane 

emissions from natural gas systems. Background paper prepared for the National Climate 

Assessment, Reference # 2011-003, OfPice of Science & Technology Policy Assessment, 

Washington, DC.http://www.eeb.cornell.edu/howarth/Howarth%20et%20a1.%20-- 

%20Nationa l%20Climate%20Assessment. pdf 

IPCC. 2007. IPCC Fourth Assessment Report (AR4), Working Group 1, The Physical Science Basis, 

Intergovernmental Panel on Climate Change. 

http://www.ipcc.ch/publicationsand data/ar4/wg1/en/contents.html 

IPCC. 2013: Climate Change 2013: The Phsical Science Basis. Intergovernmental Panel on Climate 

Change.https://www.ipcc.ch/report/ar5/wg1/ 

Miller SM, Wofsy SC, Michalak AM, Kort EA, Andrews AE, Biraud SC, Dlugokencky EJ, Eluszkiewicz J, 

Fischer ML, Janssens-Maenhout G, Miller BR, Miller JB, Montzka SA, Nehrkorn T, and Sweeney C. 

2013. Anthropogenic emissions of inethane in the United States . Proceedings of the National 

Academy of Sciences, doi 10.1073/pnas.1314392110 

Shindell D, and others. 2012. Simultaneously mitigating near-term climate change and improving 

human health and food security. Science 335: 183-189. 

UNEP/WMO. 2011. Integrated Assessment of Black Carbon and Tropospheric Ozone: Summary for 

Decision Makers. United Nations Environment Programme and the World Meteorological 

Organization. Nairobi, Kenya. 

U.S. Environmental Protection Agency Office of Inspector General. 2013. EPA needs to improve air e 

missions data for the oil and natural gas production sector, EPA OIG, Washington, D. C.