I corresponded with Dr. Robert Howarth since I posted an article about his research into the climate impact of gas here last week.  Howarth is the scientist who is saying gas has a greater climate impact than coal. 

 Howarth emailed to say his opinion is based on several points.  One, the latest research indicates methane has about 30% greater climate impact than the IPCC AR4 stated, and two:  “I believe they are severely underestimating the methane leakage”.    

GWP charts


Howarth drew my attention to  the work of Dr. Drew Shindell, a senior climate scientist at NASA G.I.S.S. who published new data on methane in October 2009.  Shindell was the lead author of a paper published in Science.  Here is the press release

The work of Dr. Shindell’s group is solid.  They were able to quantify and add in the effects of methane/aerosol interactions which the IPCC’s AR4 couldn’t include because the discovery was made after its cutoff date of May 2006 . 

 “What happens is that as you put more methane into the atmosphere, it competes for oxidants such as hydroxyl with sulphur dioxide…   More methane means less sulphate, which is reflective and thus has a cooling effect. Calculations of GWP [a way to calculate climate impact] including these gas-aerosol linkages thus substantially increase the value for methane.”    (this Shindell quote is from this article)

Shindell says “although our calculations are more complete than previous studies”, he knows he hasn’t accounted for everything.  But he said the nature of what is not certain enough to include in calculations now “would simply increase” his calculated value for methane as opposed to other gases he studies.  I.e., the GWP numbers for methane “may still be too low”.

 Howarth believes Shindell’s data is good.  He wrote in his email: “several of the IPCC authors responsible for the AR4 figures agree with me that it is appropriate to use the most recent estimates”

 Keith Shine, of the University of Reading, one of the originators of the GWP concept, said that Dr Shindell’s work would help to refine this. “It does change the picture quite significantly,” he said.  – (this quote is from this article)

 On Howarth's second point, that most analysts “severely” underestimated leakage:  he mentioned several papers.  I haven’t had time to assess these.  I put them up here because The Energy Collective had a Webinar discussing natural gas Nov 30. 

Howarth:  “We believe leakage is at least 1.9% and perhaps 5.6% or greater”.  Howarth’s high end figure of 5.6% makes gas worse than coal even if viewed over 100 years.

We'll discuss why Howarth believes leakage could be this high in a moment, but first let's have a word from an industry determined to keep on ignoring the problem that environmentalists still support because they bring us all this ‘green’ gas.  Here is a Youtube video showing methane leaking from industrial sources.


This photo of an oil storage tank at the left looks ‘normal’ but the same tank photographed on the right with an infrared camera shows the methane pouring out.


Methane shows up clearly on infrared precisely because it presents such a strong barrier to infrared radiation, i.e. it is a potent greenhouse gas. This is how hard a gas leak is to find.  You get an IR camera, point it at your equipment, and you get a picture like this.  This picture was also published in an article in the NYTimes. A large section of US industry can't be bothered to do it. 

(An aside:  Revkin at Dot Earth, in Keeping Natural Gas in Pipelines, Not Air notes that a lot of gas companies continue to ignore leaks, even though companies such as BP have shown for the last decade that stopping leaks saves three times as much money as it costs.  This is one result of BP “accepting the message from the rocks”, i.e. taking global warming as serious, compared to the typical US company attitude.  And here's another post of Revkin's, i.e.  “A Greenhouse Gas that is already a Commodity”  The point Revkin makes in this is that unlike the proposed carbon price on CO2, there is already a price on natural gas.  Gas is what the industry sells.  Even that price doesn’t make them control their emissions, unless intangibles are mixed in, like our CEO says we have to do it because he’s brought in a new company slogan ("Beyond Petroleum") and he's out there making speeches to the G8 admitting that he believes that climate change is serious.)

Back to Howarth.  According to him, “the DOE ignores a lot of information” on leaks. 

He cites as one example the paper “Estimate of methane emissions from the US natural gas industry” which he says shows the DOE ignores accidents, and that the DOE only studied plants the industry wanted them to study.  Chemosphere 35:  1365-1390  (Sorry about no live links to some of these papers:  I got them from behind paywalls from a computer at the university)

 To illustrate that the DOE approach was verified to be too low at processing plants and refineries Howarth cites, as an example: “Direct Measurement of fugitive emissions of hydrocarbons from a refinery” Journal of the Air and Waste Management Association 58:  1047-1056 

Howarth also said for "well-head" emissions, "which the DOE seems to ignore", "we rely heavily on industry" sources, i.e. for example, Shires, et.al. (2009) Compendium of Greenhouse Gas Emissions Methodologies for the Oil and Natural Gas Industry.  August 2009.  Prepared by the URS Corp. for the American Petroleum Institute (API).  API, Washington D.C. 

 And he states “for our low end estimate of leakage from pipes we used the latest direct measurements from… Europe (there are no data in the US)”.  He noted that: “these are low, since they do not include accidents, etc.  Note that these pipelines are newer than the average for the US”.  And for the high end estimate, he says:  “we used accounting data for lost and unaccounted for gas in Texas”.  He says “this gives us a range that is within that reported by one of the only other peer reviewed papers out there, with a similar mean”.  The paper he refers to here is Hayhoe et.al.:  “Substitution of natural gas for coal:  Climatic effects of utility sector emissions.”  Climatic Change 54:  107-139

(Note:  one panel member on The Energy Collective Webinar "Natural Gas: Friend or Foe to Energy Sustainability", after deflecting a question about Howarth's research by referring to a summary of his preliminary work done months ago which he described as not "impressive", claimed European natural gas use results in essentially "zero" emissions of methane.  We'd like to see some "impressive" research backing this statement up sometime.)

Howarth says that Hayhoe et. al. found that “coal is better than gas for many scenarios going out for several decades”, but “if you use the latest GWP from the 2009 Science paper it makes the gas far worse“  And he pointed out that the assumptions Hayhoe made about methane leaking from coal processing are not supported by IPCC data, in other words coal is better than the Hayhoe paper assumed. 

 A last point Howarth made is that studies of radiocarbon in methane that is currently in the atmosphere mean that “the amount of methane coming from fossil sources is much greater than has been estimated in the past”.  He cites Lassey et. al. “The atmospheric cycling of radiomethane and the ‘fossil fraction’ of the methane source”  Atmospheric Chem. & Physics 7: 2141-2149 (2007)   

Many people would like to ignore this research.  There is a lot of momentum behind using natural gas as a “bridge” fuel.   As Michael Brune, director of the largest environmental group in the world, the Sierra Club, tells us:  “we need to use natural gas as our country makes the transition from the dirtiest energy sources (coal and oil) to clean and renewable sources like wind and solar.”  (the quote is from his blog)

 One reason methane gets little attention was described on NPR:

 “Mohamed El-Ashry at the United Nations Foundation says part of the reason has been a fear by governments and advocates that attacking methane would be a dangerous distraction.  "People are worried about diverting attention away from carbon dioxide," he says."

 But this is getting preposterous.  Shindell published another chart in his paper in Science I referred to above.  He calculated the total effect methane has had compared to CO2 from 1750 to 2000, to warm the planet, taking his new research into account:

 chart from shindell


Methane has been about 60% as large as the CO2 part of the driving force for climate change all this time. 


Dr. Shindell has been studying methane for a long time.  E.g.:  see this paper published in 2005. 









When Shindell writes about what needs to be done about climate, as he did in his “Climate Change is All About Energy” he says “fossil fuels” are the problem.  He doesn’t separate gas from coal.  He writes “improvement in renewable energy from wind, solar, and nuclear power should be at or near the top of national priorities”.  He calls for more “efficiency”. 

 But Shindell laments:  “Continued use of fossil fuels is inevitable for the immediate future, and potential solutions such as carbon sequestration and nuclear power require further study or remain controversial” 

Perhaps its time to make the use of natural gas controversial.