RealClimate logo

Technical Note: Sorry for the recent unanticipated down-time, we had to perform some necessary updates. Please let us know if you have any problems.

Fracking methane

Filed under: — gavin @ 16 April 2011

The Howarth et al paper estimating the climatic impact of shale gas extraction by hydraulic fracturing (fracking) has provoked a number of responses across the media. Since the issue of natural gas vs. coal or oil, and the specifics of fracking itself are established and growing public issues, most commentary has served to bolster any particular commenter’s prior position on some aspect of this. So far, so unsurprising. However, one aspect of the Howarth study uses work that I’ve been involved in to better estimate the indirect effects of short-lived emissions (including methane, the dominant component of shale gas). Seeing how this specific piece of science is being brought into a policy debate is rather interesting.

The basic issue is that for any real economic or industrial activity there are a variety of emissions associated with the life cycle of that activity – from construction, transport of fuels, operating emissions, end products etc. In deciding whether one activity is ‘better’ or ‘worse’ than an alternative, people need to have an assessment of the cost, the carbon footprint, other impacts etc., over that whole life cycle. There are of course different elements to this (cost, pollution, social issues) that need to weighed up, but one piece that is amenable to scientific analysis is the impact on climate drivers.

Calculating the net climate impact of an activity requires tracking many different emissions (not just CO2), and accounting for their (time-varying) impact on radiatively active components of the atmosphere or the properties of the affected land surface. While straightforward in conception, this can be complex and, inevitably, there are uncertainties in assessing all the knock-on effects. Over the years, many of the complexities have become better acknowledged which, in some cases, increases the total uncertainty, but the alternative of assuming that the indirect effects have zero impact with zero uncertainty is not tenable.

For shale gas extraction, (and indeed for most fossil fuel extraction), a big issue is fugitive emissions. These are emissions that arise by accident – mostly consisting of methane, but also other volatile organic compounds – as a function of the mining, refining, transport, or incomplete combustion. Since methane is a relatively powerful greenhouse gas whose source is dominated by anthropogenic activities at present, the impact of the fugitive emissions can be a significant component of the climate forcing associated with any activity.

The Howarth study, using admittedly poor observations (for lack of anything better), has come up with a relatively large potential for fugitive emissions from the fracking process itself – up to a few percent of the extracted gas. Converting this into an equivalent CO2 amount (for comparison with the impact of the gas once it is combusted), they have used Global Warming Potentials (GWPs) from Shindell et al (2009) (a paper I co-authored). A GWP is a kilo-for-kilo comparison of the radiative forcing associated with the emission of particular substance compared to CO2, integrated over a specific time frame. For a long-lived gas like CO2, forcing persists over a long time, while for a shorter lived species (like methane), the forcing goes down faster with time. Therefore the time frame for the GWP calculation matters a lot for the relative importance of the two gases. Methane is relatively more important for a 20 year time frame, than it is for a 100 year time frame, by about a factor of 3.

There are indirect effects from methane emissions because it is chemically reactive in the atmosphere. It contributes to increases in tropospheric ozone and stratospheric water vapour (increasing the warming impact), and by changing the oxidising capacity of the atmosphere, affects it’s own lifetime, and that of SO2 and NOx – which in turn affects aerosol formation, and indeed aerosol-cloud interactions. The IPCC (2007) report had acknowledged the potential for these indirect issues, but had not given any numbers. The Shindell et al paper was an attempt to fill that gap. As we discussed previously:

… we found that methane’s impacts increased even further since increasing methane lowers OH and so slows the formation of sulphate aerosol and, since sulphates are cooling, having less of them is an additional warming effect. This leads to an increase in the historical attribution to methane (by a small amount), but actually makes a much bigger difference to the GWP of methane (which increases to about 33 – though with large error bars).

For comparison, the GWP in IPCC (2007) was 25 – this is for a 100 year time frame. For shorter periods like 20 years, the relative increase in our numbers was somewhat higher (about 50%) over that given by in AR4.

Thus a combination of high fugitive emissions, and larger updated numbers for the impact of methane are the main components the Howarth conclusion, relating the impact of shale gas to coal. However, for an apples-to-apples life cycle comparison, one would need to also update the impacts of coal and oil to include their fugitive emissions, their impact on other short-lived components (black carbon, CO, etc). Thus, it’s not clear that the Howarth comparisons are exactly on a level playing field. Regardless, the uncertainties in some of these estimates are such that very clear conclusions are going to be elusive for some time to come.

A few further points are worth making. The estimates for fugitive emissions are uncertain because they are not being reported, either voluntarily by the industry or through regulation from the states. It is also worth stating that there is nothing inevitable about fugitive emissions. Better management (and/or regulation) can reduce these losses substantially (up to 90% in some situations) in very cost-effective ways (since lost methane is lost product in many cases).

Which brings me to the responses to this story. The industry website Energy in Depth was quick off the mark with a response that feigned surprise and shock that the emission estimates were uncertain (somewhat hypocritically since it is the same industry that has resisted almost any improvement in reporting standards). They also try to imply that the Shindell et al study was somehow suspect because it was different to the earlier IPCC GWP numbers, without any apparent interest or knowledge of why that was. Again, the industry would be better advised to deal with fugitive emissions (which also impact air pollution) rather than attacking inconvenient science. (Funnier still are the contrarian responses, for instance from “Bishop Hill” who completely agrees with the industry (again without any actual knowledge of the issues), and who can’t resist using their criticism of Howarth to condemn a whole University (and by proxy, the whole scientific enterprise). I mean, why bother with independent scientists when the industry can tell you exactly what you are supposed to think?).

Another frequent framing is the false dichotomy. Apparently, natural gas must either be perfect solve-all or worse than useless (see for instance, Keith Kloor’s take). One would think that the overwhelming consensus that there are no panaceas for decarbonising our energy supply might have at least started to make a little impact on the media. Any real policy initiative will have complex effects, and while scientists can certainly help quantify them, nothing at the scale we require is going to be completely neutral in all particulars – and the media should stop expecting it to be so. Since there will always be people who can be portrayed as having taken a black/white position on some issue, it is all too easy to frame any new result as undermining some over-optimistic idealist, which unfortunately buries the conversation related to the nuances of real issues.

Howarth et al is unlikely to be the last word on this subject, but it does highlight the need for more of this kind of research, and for further quantification of these emissions and their effects. For anyone interested in the larger issues of time-scales and the implications of combining emissions of short-lived and long-lived species in assessing impacts, I recommend reading the latest UNEP report on Black Carbon and Tropospheric Ozone mitigation (at least the summary). Another relevant read is the post by Ray Pierrehumbert on the same issue. This is not just an issue for fracking, but rather something that is far more general and affects almost all emitting activities.

88 Responses to “Fracking methane”

  1. 1
    Snapple says:

    “Not every housewife is aware of the environmental consequences of the use of shale gas…I don’t know who would take the risk of endangering drinking water reservoirs.”—Alexander Medvedev, Director-General of Russia’s Gazprom Export (Reputed former KGB offier)

    Gazprom has expressed not-very-sincere environmental concerns about fracking and has been watching the EPA study this issue.

    This is right in the media, so you can actually see what they are doing.

    Of course, Gazprom has “gone green” on this issue because they want to sell liquified natural gas in America.

    I wondered what is worse environmentally: fracking or buying Russian natural gas. If you buy their gas, they tend to buy up your politicians–that has already happened in Europe.

    I would rather put a lot of money into renewables.

  2. 2

    Re 1, Snapple,

    I think you are almost on the right track here, but not quite.

    I would say that Medvedev is happy to discourage production of shale gas in Europe and America so that their already abundant output will be more valuable.

  3. 3
    Matt Hall says:

    I’m an oil industry geoscientist, so you may find that my “commentary [serves] to bolster [my] prior position…” (not sure why you’d expect anything else — that’s kind of the point of making a comment!) But I just wanted to say that I was surprised the authors don’t mention flaring at all. The practice of burning vented gas is obviously not a great way to deal with the problem, but at least it reduces the emissions to (more or less) what they would have been if the gas had made it to the consumer. From other things I read, this for example, admittedly from industry advocates, but still data, it looks like a lot of gas is generally captured and flared. As you can imagine, venting a lot of methane near a wellsite is rather dangerous, so I think the industry tries to capture it for flaring. I could be wrong, but it just struck me as a bit of an omission, since the paper does not mention it.

  4. 4
    Miguelito says:

    I’m going to preface this comment by saying that the oil and gas industry has earned every bit of the public’s skepticism when they claim something is clean or green. No doubt about it, if they told me my house was on fire and I turned to see smoke and flames, I’d still be a bit skeptical. Let me also say that the Energy in Depth article, while it gets some technical points right, is a bad stab at communication — it reads childish and vindictive and certainly does not help produce any useful dialog.

    But, like I’ve said elsewhere, the Howarth estimate is probably significantly inflated.

    Flowback gas from shale wells is flared, not vented, and, while the CO2 has its footprint, it’s not nearly as high as the methane’s. Further, Howarth’s estimates for venting during drilling out plugs originates from tight gas wells, not shale gas, and tight-gas is treated very differently from shale-gas wells as to when they drill out plugs (in shale wells, plugs get drilled out before flowback begins and there’s very little gas in the well at that point).

    This probably more than doubles the direct emissions of methane during flowback in Howarth et al’s low case and shrinks their high case down by 20% and maybe more. The problem is that none of the authors really have a grasp on the operational side of the oil and gas business (two biologists and a civil engineer who specializes in fracture propagation — Ingraffea is no doubt a really brilliant guy with some experience in the oil and gas business, but it’s a real stretch to consider him an expert in energy systems). They based their estimates on a EPA 2010 report, but that 2010 report is based on 2007 and earlier data and alot has changed since 2007. Low-flow wells, like CBM and tight sands, yes, have a history of having their gas vented during flowback, as is indicated in the EPA study. However, shale wells, because they produce like gangbusters, have their flowback gas flared, otherwise, it can become a complete disaster (for example, please see BP Macondo disaster for what happens to “vented” methane around diesel engines).

    It’s not a particularly big surprise that this mistake was made considering the lack of experience and understanding of oil and gas operations, especially some context about what’s changed from 2007 to 2010 and 2011. It can also be considered a parallel to flawed analyses made by non-expert climate-change deniers.

    As for the high case, the estimate of leaked gas from pipelines and compressor stations is probably unrealistic given that more gas is being produced and then consumed within the local region rather than imported over long distances (a shorter distance of pipeline travel means fewer places for it to leak — for example, less gas has to flow 1500 km from Canada and only needs to flow a few hundred km from Pennsylvania to NY State).

    Now, I do agree that there needs to be a better demonstration of the risks (although, there are many, many studies on conventional gas, just not much in the way that’s included unconventional). Using a higher GWP for methane than in IPCC (2007) is reasonable. But I’d prefer any study get done by somebody like Paulina Jaramillo, who has a good background in this kind of stuff or somebody else with experience, so that potential problems with the data can be foreseen and dealt with appropriately. Hopefully, a study like Howarth et al’s gets more going in the pipeline (yuk yuk) if only to refute it. Further, hopefully it gets companies to release some real data, a real constraint on doing these kinds of analyses (I really sympathize with Howarth and how scant the data is to use on something like this). The industry says they want policy made on science but all so often refuse to submit any. Well, it’s time to cough it up if they want to be taken seriously. Until then, the EPA a number is a decent, even if it might be a bit low, start.

    Again, it’s not that I have great love for the oil and gas industry, because I don’t. They create most of their own messes and then deny until the lawyers pay up in lawsuits or buy politicians. I just like good analyses, and I doubt this is one of them.

  5. 5
    James Newberry says:

    RE: “One would think that the overwhelming consensus that there are no panaceas for decarbonising our energy supply . . .”

    Dear Sir:
    While I am respectful of your science acumen and know this site to be a valuable contribution to the study of climate science, your framing of such statements as the above hamper your ultimate understanding. After a lifetime of studying technology and policy I content that your statement as read is patently false. In point of information, there is a vast literature asserting the opposite.

    One might start by speaking truth. If we may categorize all known physical phenomena on earth as either matter or energy, then lithosphere carbon, which exists in the solid, gas or liquid state, is a form of Matter, not Energy. Thus, petroleum is not “energy supply” but a “material,” a resource of matter. Statements about “decarbonizing energy” or even “stored energy,” rather than “stored matter,” become a bit “Alice Through The Looking Glass,” if you will.

    Humans may be counting global “energy” at the rate of some 16 TW, yet the sun’s energy delivered at the planet’s surface is some 12,000 TW.

    Kind regards, JRN

  6. 6
    Edward Greisch says:

    \there are no panaceas for decarbonising our energy supply might have at least started to make a little impact on the media. Any real policy initiative will have complex effects, and while scientists can certainly help quantify them, nothing at the scale we require is going to be completely neutral in all particulars\

    Yes. Thank you. That is very difficult for the media because:

    1. Journalism school does not require mathematics or science.
    2. The average public didn’t go to college and took only the minimum courses to graduate from high school.
    3. Ditto for politicians.
    4. None of the above 3 groups understands that we really mean what we say. \The end of civilization in the 2050s\ is not hype and we really can predict it. Our inability to predict the stock market is irrelevant.
    5. An energy source that works well in one area does not necessarily work well, or at all, in another area. It is best to let the engineers do the engineering.

    The federal government should limit the CO2 + equivalent per kilowatt hour, not specify the source of the energy. Specifying the source leads to gridlock rather than action.

  7. 7
    Andy S says:

    I would second Miguelito’s comments above @4. Well said.

    It seems odd to me that the gas industry is not more punctilious about accounting for gas volumes between wellheads and burner tips. If it were money that went missing in this way then shareholders, regulators and, maybe, the police would show concern. (What’s especially odd is that for gas companies methane actually is money.) Fugitive gas can also amount to fugitive resource royalties in some jurisdictions, so even climate-skeptic citizens should be concerned.

    A certain \auditor\ has recently demanded an engineering-level study on climate sensitivity. Perhaps it’s only fitting that Howarth et al are demonstrating the need for a science-level survey of industrial engineering practices.

  8. 8
    Keith Kloor says:


    My take (in the post you cited) is that there is a schizophrenic quality to the media coverage of natural gas. To a large extent, I think this reflects the ambivalence (split?) in the climate/environmental community with respect to natural gas as a “bridge” fuel. That’s the point I was trying to get across.

    Ironically, the dichotomy you mention was on ample display this week, during much of the coverage of the Cornell shale gas study. For the most part, the media parroted the conclusions drawn by Howarth et al. In another post, I discuss that coverage here:

  9. 9
    Johnno says:

    Aside from fugitive emissions natural gas still has a couple of major problems. When burned in power plants the CO2 emissions are 45%-75% that of coal for similar electrical output. Long run it won’t get us to say 80% CO2 reductions. Natural gas is currently needed to balance the variable output of all the wind and solar plants that have been spurred by subsidies and mandates. What happens when gas runs out? Alternative fast response electricity sources like hydro may also be limited.

    I make it three strikes against natural gas; still high CO2 when burned, looming failure of co-dependent intermittent energy sources and now fugitive emissions. I think we need to ration natural gas supplies for a century not use it all in just decades. If done right we could get lower rates of CH4 and CO2 with more sustainable energy generation.

  10. 10
    Lynn Vincentnatnathan says:

    I’d like to point back to David Archer’s “Methane Hydrates & GW” at

    Altho it’s about melting hydrates, it points to the compounding effect of fast release of CH4: if there are huge releases within a 10 year period (whatever the source) the effect would be greater, than a slower release over, say, 100 years.

    Also, I think someone’s pilot light just went off …..

    Luckily I get a type of “gas” headache whenever there’s a gas leak, so when we had a home with gas energy, I always knew when the pilot light went off, even when there was a tiny leak in the garage (while it took the gas man an hour of searching all over — doubting me all the time — to finally find it with his detector).

    If people would only use their heads…

  11. 11
    David B. Benson says:

    Johnno @9 — Here in the Pacific Northwest the ~3.3 nameplate GW of wind generators are currently backed by our extensive hydro capacity. It appears that future wind generation will mostly be backed by fossil fuel fired generators.

  12. 12
    Greg Simpson says:

    Apparently, natural gas must either be perfect solve-all or worse than useless (see for instance, Keith Kloor’s take).
    Worse than useless does seem right for the long term. We need to stop using natural gas almost as badly as we need to get off coal. What we don’t need is more solar or wind than we can handle without natural gas backup.

  13. 13
    Reed Maxwell says:

    Nice Battlestar Galactica Reference.

  14. 14
    Lloyd Smith says:

    The political solution to reducing methane leakage during production and transport is to create incentives for companies to improve their pipeline stock. Many companies forego needed capital investment to improve their cash positions and potential shareholder return. Global governments (partially controlled by oil/gas lobbies) have no intention on changing incentive programs for the oil and gas industry. Until incentives change, “science” has no hope of reducing climate forcing related to methane production.

  15. 15
    Lou Grinzo says:

    I have no idea how the science re:the Howarth paper will sort itself out (to borrow a phrase from economics), but even in the optimal case — the conclusion is incorrect and greatly overstates the impact of fracking — NG is still a terrible idea.

    Replacing gasoline in vehicles with CNG only results in a reduction in CO2 emissions of about 20 to 25%, conspicuously at odds with NG’s image as a “clean” fuel. (If CO2 were dark gray and smelled really bad, fighting climate change would be dramatically easier.)

    And as someone pointed out above, NG provides nowhere near the CO2 reduction, compared to coal, that we need. Building NG plants with a 40 to 60 year operating lifetime would provide a short-term move in the right direction, but in a decade or two those plants would help strand a country like the US above the required emissions curve.

    Thanks, Gavin, for an interesting and informative post on a critical topic.

  16. 16
    Mark A. York says:

    According to filmmaker Josh Fox, fracked gas costs 20 percent more than coal in energy spent or something to that effect. He produced the oscar nominated film, Gasland. My current novel concerns gas drilling and hydro-fracturing.

  17. 17
    frflyer says:

    The answer to some of the issues raised @11 and @12 is large scale solar thermal base load power with heat storage.

    Here’s a how a 1250MW CSP plant with 3.5 hours molten salt heat storage would operate in Nevada in mid-summer. Winter operation would be similar but at lower output.

    The plant would start saving heat at sunrise. A few hours later, it would start generating electricity and continue storing heat in the salt. By 1pm when the sun peaks, it would be at full rated power, 1250 MW. It would continue to put out at least it’s full rated power, while increasing output and peaking at about 3,000 MW at 5pm, exactly when demand in the grid peaks in the southwest. It would continue putting out steady but declining power until midnight.
    No power fluctuation when clouds pass by.

    Cloudy periods, which are rare in the southwest can be planned for by the plant manager and utility, from weather forecasts. In the daytime in what the NREL calls Premium Solar Resource areas, there is sunshine all but about 4% of the time.

    3.5 hours heat storage means enough to provide 3.5 hours at full rated power, without any input from the sun.

    The first plant with molten salt heat storage in the U.S. is being built in Arizona. It will have 6 hours heat storage.

    A solar thermal plant can adjust power output to meet demand. Lots of excess wind energy in the grid? A CSP plant can hold off on power generation, saving heat in the salts and dispatch it later when it’s needed. The most versatile of all our renewable energy choices.

    A company called Shec Energy has developed what appears to be disruptive technology for solar thermal. CSP plants of their design would run at twice the temperature of current solar thermal plants. 800-900 C verses about 450 C. And they can store heat at that temperature.

  18. 18

    The main gut of this article is that the jury is out. As so it will be for a long time.

    Same goes for the question whether or not electric cars are a net benefit in our attempts to combat climate change. Much controversy. And so there will be for a long time.

    Any attempts to use alternative fuels or alternative technologies to try to maintain our consumer lifestyles are underpinned by many competing processes. Though the devotees of each technology find this laggard science frustrating, there’s not much point doing things that in the end only serve to worsen the situation.

    And that brings us to an obvious conclusion, virtually any technology or behaviour changes that reduces energy consumption has much clearer signals as to its effectiveness. To save a kwh is almost invariably worthwhile doing. To produce a kwh of energy, by whatever means, invariably is a less worthwhile enterprise, because there are always significant hidden costs associated with energy production – whether that be bird strike on wind turbines or fugitive emissions from coal seam gas.

    Motto: Always look to abatement measures as first priority, and only then look to alternative means of production.

  19. 19
    Les Johnson says:

    Some unlikely sources of criticism of Howarth; including MIT, NRDC, Council for Foreign Relations and Clean Air Task Force:

    Posted April 13th, 2011 by Dave McCabe, atmospheric scientist

    • “This paper is selective in its use of some very questionable data and too readily ignores or dismisses available data that would change its conclusions.”

    • “The authors’ choice as to which data to use for leaks from natural gas processing, transmission, and storage systems is also a big concern. They recognize the limitations of EPA data, then use those limitations to dismiss the EPA work, and then use higher values, which come from even more questionable sources. … These two decisions alone result in unrealistically high emissions.”

    Full post:

    Posted April 12, 2011 by NRDC’s Dan Lashof

    • “While these higher figures were produced by well respected researchers, they have not yet been subject to the level of review and scrutiny conducted by the IPCC for its estimates.”

    • “[W]hile I can see an argument for using a time horizon shorter than 100 years, I personally believe that the 20-year GWP is too short a period to be appropriate for policy analysis because it discounts the future too heavily.”

    • “Relatively few actual observations were used to estimate ‘emission factors,’ which were then extrapolated to estimate emissions from the system as a whole.”

    Full post:

    Posted April 15, 2011 by CFR’s Michael A. Levi

    • “The data for leakage from well completions and pipelines, which is where [Howarth] is finding most of his methane leaks, is really bad.”

    • “Howarth’s gas-to-coal comparisons are all done on a per energy unit basis. That means that he compares the amount of emissions involved in producing a gigajoule of coal with the amount involved in producing a gigajoule of gas. … The per kWh comparison is the correct one, but Howarth doesn’t do it. This is an unforgivable methodological flaw …”

    • “I worry about what this paper says about the peer review process and the way the press treats it. … These reviewers don’t appear to have been on the ball. Alas, this sort of thing is inevitable in academic publishing. It’s a useful caution, though, against treating peer review as a mark of infallibility … “

    Full post:

    MIT Energy Initiative exec. director Melanie Kenderdine, interviewed by CNBC on April 12, 2011

    • “What he has done in his analysis is deviated from what are accepted standards, accepted by EPA, DOE, the IPCC, European Trading Scheme, California Air Resources board, where essentially the denominator that they use to calculate the impacts of various greenhouse gases is an agreed upon 100 years; Professor Howarth uses 20 years.”

    • “[T]here are major scientific organizations that think we should actually extend that hundred-year period, not shorten it. So he has changed what is a standard number for calculating the impacts of greenhouse gas emissions … “

    Full segment:

    [Response: I think the comment by Melanie Kenderdine is especially important. Howarth has inflated the impact of leakage by using an inappropriately short window for computing GWP. As Kenderdine notes, just because a lot of policymakers seem to have settled on 100 years as a window, there's nothing magic about that number. Many of us feel (see my post linked by Gavin above) that because of the very long lifetime of the warming caused by CO2, anything short of a thousand years is ridiculous. I'm quite sure that if a thousand year window were used for GWP, then Howarth's case would go away even if his leakage figures were correct. I need to run the numbers, though. If they look interesting I'll do a short update post on how the frakking issue relates to the methane vs. CO2 lifetime dialog. --raypierre]

  20. 20
    Lynn Vincentnatnathan says:

    RE #3 & flaring. Hi Matt, I’ve seen flaring in various places. I was just wondering if it might be feasible to turn that flaring into useful energy — accomplish some task, transmit it into the grid, or into ? batteries ?

  21. 21
    Les Johnson says:

    One can falsify Howarth’s paper, simply by looking at the atmospheric methane concentrations over the years.

    While it is rising again, it was flat, or even declining, for over a decade; over this same decade,global gas production increased 25%. If gas was indeed leaking at the rates Howarth used, then atmospheric CH4 would NOT have flattened.

    OH chemistry changing to clean out CH4? Nope. It is, and has been stable.

    One should also look at the economics of gas leakage. Global gas production is about 3 trillion M3 per year.

    At $4 per 1000 cuft, that would be about 13 billion per year just wasted. At the higher prices we saw in 2005-2008, it would be 30 to 40 billion dollars per year lost.

    I don’t think any company would have this in their business model.

  22. 22
    Les Johnson says:

    Lets do the math:

    According to Wiki, the atmosphere is about 4.2 billion billion m3. The IEA says about 3 trillion m3 of gas is produced each year. Howarth says about 3% of that leaks, or about 90 billion m3 of CH4.

    Cancel the billions, and we have 90 m3 of CH4 per 4.2 billion m3 of air, or 21.4 ppb per year.

    The last few years, CH4 has gone up by 6 to 8 ppb per year, depending on the author. Before that, it was zero, or less, for more than a decade.

    In other words, using empirical data, we can suggest that actual CH4 leakage from gas wells is negligible, and nowhere near the value used by Howarth.

    [Response: The budget for methane is complicated given the various sources (irrigation, landfills, fugitive emissions from all sources, agriculture etc. - as well as all the natural sources). So without a good control on all the others time histories, it is very difficult to constrain any one specific source based on the annual changes. It is not inconceivable that the increase in shale gas exploration in the last 5 years has contributed to the recent upticks, but very hard to prove. - gavin]

  23. 23
    Jerry Unruh says:

    I am interested on your take on two recent papers that discuss \peak coal\. While not exactly on target with this post, they are certainly related. The two articles are: International Journal of Coal Geology, volume 85 (2011), pp. 23-33 (DavidRutledgeCoalGeology.pdf) and Patzek+and+Croft+2010+-+Peak+Coal+2011.pdf which is in Energy, Vol 35, pp.3109-3122 (2010). Thanks in advance.

  24. 24

    To #2: at the end of the day, we can sum this subject up by saying everything is money related. Governments don’t really care about the environment if it hit their pocket too much.

  25. 25
    Les Johnson says:

    Gavin: Its very easy to prove. Gas production increased 25% over the period that methane levels were flat. If gas did indeed leak at the rates suggested by Howarth, then we would have seen methane levels increasing by a similar rate as production.

    If you are adding more methane to the mix, and the scrubbing mechanism is the same, then the methane should increase. It didn’t increase, for a decade. Only if the drop in natural production EXACTLY matched the increased Anthro CH4, would you get a flat line. How likely, year after year?

    Empirically, if gas leaked at the rates suggested by Howarth, then methane levels should be increasing by 21 ppb every year. It would be even more in the NH, as the vast majority of gas is produced in the NH.

    Until you can a find a way scrub that 21 ppb without OH chemistry, there is no way that 90 billion m3 of gas will leak every year, and not increase atmospheric CH4.

    Either there is an unknown scrubbing agent; or natural variation EXACTLY matched man made increases; or there is negligible leakage.

    Occam’s razor.

    [Response: You are assuming that all other sources are flat. They are not. There are changes in agricultural emissions, changes in natural emissions (as a function of rainfall/temperature patterns), ongoing efforts to capture methane from landfills, reduce other fugitive emissions (i.e. from conventional pipelines etc.). All I am saying is that a top-down constraint on any individual source is non-trivial. - gavin]

  26. 26
    Miguelito says:


    Really hard to do in this case, because the flaring will only happen for a few days (maybe up to a week) during the flowback. Longer term well tests (where pipeline infrastructure is not present to flow into) would be more of a possibility, but it probably won’t happen because it’s an extra cost for a commodity like electricity which isn’t in much demand on a wellsite and difficult to hook up to the local grid.

  27. 27
    CM says:

    Hi, Lynn (#20), re: energy from flaring,

    Better capture as much of the gas as possible and put it to good use in the right place. Recovering energy from big flames coming out of the ground won’t be efficient.

  28. 28
    Les Johnson says:

    gavin: your

    It is not inconceivable that the increase in shale gas exploration in the last 5 years has contributed to the recent upticks, but very hard to prove.

    Nope. While shale gas activity may have increased, total gas production over the last few years is relatively flat, at about 3000 billion m3 per year. It even fell the last year of full records.

    2006-2880.2 2007-2954.7 2008-3060.8 2009-2987.0

    Increases in production in the US were more than offset by decreases in Russia and Turkmenistan.

    The decade prior, though, saw large increases in production, but flat methane levels. The last few years has seen flat production, but increasing methane. The two indicators are not moving together and haven’t for 15 years; ergo, they are not closely linked; ergo, there is negligible leakage.

    Granted, there can be some unknown mechanism involved, but its unlikely, especially at the leakage rates proposed by Howarth. That much leakage would have to show up in methane levels.

  29. 29
    Snapple says:

    Re: Flaring 45% of gas prodution in Russia

    “In August 2007, the then President Vladimir Putin set 2011 as a deadline for Russia to reduce flaring to 5 percent of the country’s associated gas production from the current 45 percent. However, in December 2008 Russian Natural Resources Minister Yuri Trutnev said that the deadline had been pushed back to 2014 (Interfax, December 4, 2008), but declined to specify any reason for the delay.”

  30. 30
    Septic Matthew says:

    Good post.

    21, 22, Les Johnson and Gavin: isn’t it likely, on present data, that ground water pollution is a bigger problem with frakking than atmospheric pollution? That’s no criticism: the paper addressed a real problem and this site is dedicated to real climate; I’m just asking.

  31. 31
    Les Johnson says:

    Snapple: they are flaring 45% of the associated gas produced WITH oil. Gas wells would not need to be flared. Oil wells need to be flared to get rid the gas, as it can interfere with oil surface gathering equipment. This is common in developing countries, like Russia and Nigeria. But, even Nigeria is moving away from the practice.

    It used to be common in North America, but is rare nowadays.

    Note that flaring is actually burning of gas, so while CO2 is produced, the GHG effect is still much less than raw gas.

  32. 32
    James Staples says:

    I think that the stupidest thing that I’ve heard of while monitoring this debate over the last few years, is the idea of using Fraking – or of extracting Natural Gas at all! – from the Yellowstone Basin (i.e.: Caldera).
    As I pointed out in a heated letter to the DOE, DOI, my Congresspeople, etc., Volcanoes are delicate things that erupt because a decrease in the PRESSURE holding back the Magma back; like that which MIGHT occur, IF you start extracting the gas/water from the shale overburden; causes a sudden ‘opening a shaken up pop can’ effect in which the Gases in the Magma suddenly come out of solution in a most violent way.
    I also pointed out that Yellowstone is due to erupt at any moment.
    Hey! At least if it does, we won’t have to worry so much about how badly we’ve been messing up the Environment, eh?

  33. 33
    Snapple says:


    Ok. That makes more sense.

  34. 34
    Gail says:

    I’m quite curious about the potential for methane to be a significant precursor to ozone, as I only just found studies indicating it has a role, and so I recently posted this:

    [With respect to methane as an under-appreciated precursor to ozone, I note parenthetically this new study, which concludes "...that shale gas developed through fracking carries a higher greenhouse gas footprint because the “fugitive” methane emissions at the fracking sites are greater than releases from conventional gas wells." and recommend the movie Gasland where the infrared images of escaped methane are shocking. I expect it would be simple to find more along the lines of this ominous snippet: "Major sink of methane is its reaction with OH leading to the formation of ozone." or this one: "Methane, a VOC whose atmospheric concentration has increased tremendously during the last century, contributes to ozone formation but on a global scale rather than in local or regional photochemical smog episodes. In situations where this exclusion of methane from the VOC group of substances is not obvious, the term Non-Methane VOC NMVOC is often used."]

    the links can be found here

    Any thoughts as to the role of methane or other emissions are welcome because I’d really like to understand
    [edit - let's not get started on that again, thanks]

  35. 35
    Gail says:

    I thing, therefore I are.

  36. 36
    Edward Greisch says:

    28 Les Johnson: Just wondering: Does a valve leak more when it is partly closed than it does when it is fully open? I’m thinking a partly closed valve would have more internal pressure than a fully open valve.

    What is “flowback”?

    Well casing gas: What is it and how does it flow through solid concrete? Or could somebody explain this stuff please?

    32 James Staples: Is there a problem with using high temperature geothermal energy from Yellowstone? Is it possible to cool the magma by doing so, and would this prevent the eruption or hasten it?

    Is there a way to “open the pop can” very slowly to get a Hawaii volcano-type flow? Wrong magma type I suppose.

    “Yellowstone is due to erupt at any moment.” I was told by a geology/paleontology graduate student that “soon” is a very long time as far as Yellowstone volcano is concerned. Do I need to move out of Illinois now and to where? How are you predicting the eruption?

    As I understand it, Yellowstone is a “Super” volcano, meaning one like Vesuvius that killed Pompeii and Herculaneum, only bigger.
    “Gases in the Magma suddenly come out of solution in a most violent way.” As in a gigaton to million megaton explosion that puts 100 cubic miles of stuff into the stratosphere? No place on Earth is safe?

    RC: Yellowstone volcano could be an interesting post since it could “reset” the climate by ending the USA.

  37. 37
    Edward Greisch says:

    The petition is at:

  38. 38

    OT… but I’d love to see a post on Xu et al 2011 and the current state of the Amazon.

  39. 39
    Mike Roddy says:

    Fugitive methane from fracking could just as easily be higher than Howarth estimated. We have no idea, since there is little monitoring or measurement.

    It’s not just fossil fuels. EIA data relies on industry submittals- for the steel industry, for example, there are gross estimates for mining emissions, but EIA lacks the personnel or inclination to check the numbers. This is even more true for the timber industry, which has a long history of falsifying or ignoring data on all kinds of subjects, but especially inventory and emissions. For example, the public has no idea that North American forest mortality has doubled since 1970.

    Homebuilders and LEED are probably the worst. They basically rely on industry claims for emissions and toxins, which- surprise!- results in the same specifications they had before, things like toxic plywood, vinyl window frames, and the whole rot of it. Our houses last a fraction as long as those in Europe.

    If someone wants to really investigate something like fracking, they are going to have to hire a qualified group that will investigate all of the variables in detail. Hard science is just the beginning: statistical training, LCA methodology, and doggedness are also required. I recommend IERE from Seattle.

  40. 40
    Phyllograptus says:

    As stated in the post “In deciding whether one activity is ‘better’ or ‘worse’ than an alternative, people need to have an assessment of the cost, the carbon footprint, other impacts etc., over that whole life cycle”
    One of the aspects not treated in the Howarth analysis is the “full life cycle” emmisions of the coal and oil they compare it too. All coal has methane adsorbed onto the organic material at a molecular level. (Shales have similar properties which is why there is such a vast reserve potential of shale gas.) Roughly 20 to 50 times as much gas can be adsorbed as can be held in the interstitial porosity. During any coal mining, either sub-surface mines or open pit mining the adsorbed methane is going to be released. (one of the reasons the old saying about canary in a coal mine saying came to be is methane released during mining creating dangerous levels of other gases reducing breathable air and creating flammable situations) As common values for the adsorbed gas in coals range from 50 to 500 scf/ton (standard cubic feet per ton) there are trillions of cubic feet of methane sorbed onto coals worldwide. Which is why CBM (Coal Bed Methane) gas production is economically viable. However, NONE of the methane released from any coal minig is even thought about or considered as a fugitive emission, therefore is not considered in the comparison. With regards to oil production huge volumes of gas are dissolved in oil. When the oil is produced the lowering of pressure as the oil comes to surface releases this gas as what is termed “solution gas”. In many countries with out export potential for this gas or in offshore production without gas gathering and distribution systems a lot of solution gas is vented or flared. Again another instance of ignoring fugitive emissions. So comparing shale gas and its fugitive emissions directly to combusting coal or oil significantly skews any analysis by willfully ignoring the “whole life cycle” of the various hydrocarbon systems and therefore overall is a completely invalid proposition.

  41. 41
    Walter Pearce says:

    Mike Roddy@39. I agree with the general premise you expressed, but wonder where you get your info on LEED. For instance, for LEED NC 2009 for New Construction, there are no fewer than eleven credits dealing with indoor air quality. There are other materials credits as well.

    As a result, LEED-based product specifications are indeed quite different from business as usual. Moreover, I can tell you from experience that specifiers working on LEED projects are on the lookout for greenwashing.

    I do agree with your larger point as I understand it. When it comes to CO2 abatement, there are massive potential savings in building siting and design, embodied carbon in building products, and — for commercial buildings — a transportation component ripe for savings.

    Looking beyond LEED, I recommend further research into Passivhaus, the Living Building Challenge, and the 2030 Challenge.

  42. 42
    Eli Rabett says:

    According to Howarth they included the fugitive emissions from coal (the volatiles released in the mining. Be that as it may, it is hard to imagine that this would be larger from fracking the gas out of the rocks as the heating value of the volatiles in coal is a large fraction of the heating value of the coal. OTOH, loss of gas from pipelines is in the less than 10% but more than 1 or 2% category depending on where. This can be controlled, but it does cost. Eli gets the feeling that Howarth threw the kitchen sink at the gas, and the smaller bathroom one at coal.

  43. 43
    David McCabe says:

    @Les Johnson, #19

    Thanks for the shout-out. As the quote from our blog states, us we’re quite skeptical about Prof. Howarth’s analysis. I tried to document why on the blog post to which you linked.

    But you did not mention another point that we prominently made in our blog post, as have many others: Our current knowledge of emissions from venting and leaks from US natural gas is unacceptably poor (both from fracking and from conventional gas wells). EPA’s estimates were increased – retroactively to 1990 – by huge amounts in the past few months. Their estimate for 2008 went up 120%!! That’s 5.5 Tg of “new” methane that just appeared in the inventories.

    We clearly need more accurate, credible measurements and inventories for the methane emissions from fracking, from other types of gas wells (most of the increase I mentioned above was from conventional wells, not fracking), and from other fossil fuels, which are also big sources of CH4. Other fossil fuels certainly shouldn’t escape some scrutiny!

    Meanwhile, as so many have noted, the natural gas industry is fighting efforts to get better data in the inventories by fighting the EPA’s reporting rules for greenhouse gases.

    We need good information about where the leaks are, and we need to get these leaks cleaned up as soon as possible.

  44. 44
    David McCabe says:

    @Gail, #34
    Methane is indeed an important precursor of ozone in the troposphere, which is an important greenhouse gas. However, this is taken into account in the calculation of global warming potential for methane – it includes the warming caused by ozone created during oxidation of methane, and also warming caused by water in the stratosphere resulting from methane oxidation up there.

    @Phyllograptus, #40
    Prof Howarth did include methane emissions from extraction of coal (and from petroleum).

  45. 45
    Rick Brown says:

    This is OT, but Mike Roddy’s statement @ 39 that “North American forest mortality has doubled since 1970” might benefit from some examination.

    I assume Mike is again referring to: van Mantgem et al. 2009. Widespread increase of tree mortality rates in the western United States. Science 323:521. (

    I think this is an important paper, but just reading the title, one might observe that the study is about the western US, not “North America” and that it refers to increasing rates of tree mortality, not forest mortality. Reading the article reveals that the study was restricted to stands greater than 200 years old.

    Interpolating from the article’s Supporting Online Material (, forest stands that in 1970 had about 460 trees/ha were down to 430 trees/ha by 2007.

    A 6.5% decrease in average density, of stands over 200 years in age, is an finding worth reporting, but is it the same as a doubling of “forest mortality?”

  46. 46
    Susan Anderson says:

    OT: NYTimes has just put out an editorial on the upcoming Supremes decision which is still at this moment open for comments. Denier central is very busy there and it could use some help:

  47. 47
    Dan H. says:

    With any luck, the court will rightfully decide with the defendants.

  48. 48

    OT, responding to #45–

    Me, I think Mike Roddy was probably correct. True, the study Rick cited was about western trees, but then the West accounts for the majority of North American forest, if I’m not mistaken. And while “tree mortality” may not be identical to “forest mortality,” I think it’s at least reasonable to assume that they are strongly related! (And the former may well have been what Mike R. intended.)

    Let’s look at some papers.


    From the abstract:

    The current outbreak in British Columbia, Canada, is an order of magnitude larger in area and severity than all previous recorded outbreaks4. Here we estimate that the cumulative impact of the beetle outbreak in the affected region during 2000–2020 will be 270 megatonnes (Mt) carbon (or 36 g carbon m-2 yr-1 on average over 374,000 km2 of forest). This impact converted the forest from a small net carbon sink to a large net carbon source both during and immediately after the outbreak. In the worst year, the impacts resulting from the beetle outbreak in British Columbia were equivalent to 75% of the average annual direct forest fire emissions from all of Canada during 1959–1999. The resulting reduction in net primary production was of similar magnitude to increases observed during the 1980s and 1990s as a result of global change5.

    This is of course a still smaller subset of data, based as it is upon numbers from British Columbia. But since the current outbreak is “an order of magnitude larger in area and severity,” and since we know that the bark beetle problem extends through most of the Rockies, from BC down to Colorado, we have a good indication that the problem is really extraordinary.


    This tells us that 15 million ash trees in “urban and forested settings” have been killed since 2002 by the Emerald Ash Borer. Many more are at risk, and containment efforts are ongoing.

    3) Of course, that’s pest mortality, which, while it has a strong anthropogenic component, may not be what Rick was thinking about. So, let’s compare two studies addressing tree mortality:
    (A study of fire-suppressed old-growth forest in California, showing overall stem mortality at 8.7%)
    (A study of a Mexican mixed forest with no fire suppression, showing “cumulative mortality rates of 2.7-3.6%.)

    Now, I can’t tell for sure if this is apples-to-apples or not. But it appears to suggest that perhaps fire suppression is increasing tree mortality, at least for old-growth mixed forest.


    Here’s a study looking at drought mortality in the Southwestern US in response of the drought of 2002-2003. 90%. This one’s definitely food for thought.

    All studies so far come from the first page of a Google Scholar search. (“forest mortality north america,” 2005-2011.)

    Searching “tree mortality” instead–this seems to be the normal terminology–brings up this:


    From the abstract:

    Here we present the first global assessment of recent tree mortality attributed to drought and heat stress. Although episodic mortality occurs in the absence of climate change, studies compiled here suggest that at least some of the world’s forested ecosystems already may be responding to climate change and raise concern that forests may become increasingly vulnerable to higher background tree mortality rates and die-off in response to future warming and drought, even in environments that are not normally considered water-limited. This further suggests risks to ecosystem services, including the loss of sequestered forest carbon and associated atmospheric feedbacks. Our review also identifies key information gaps and scientific uncertainties that currently hinder our ability to predict tree mortality in response to climate change and emphasizes the need for a globally coordinated observation system. Overall, our review reveals the potential for amplified tree mortality due to drought and heat in forests worldwide.

    OK, that one definitely goes beyond the American west.

    6) Returning to North America, and the search for “tree mortality” papers, it does seem that the Northeast, or at least parts of it, has been less affected so far–so one study from the search (not linked here) affirms. Yet the future appears to be less secure.

    . . . ongoing increases in growing season. . . will most likely evapotranspiration and frequency of drought [increasing] the risk of fire. . . Climate and hydrologic changes could have profound effects on forest structure, composition, and ecological functioning. . .

    This sentence from the abstract emphasizes the projective aspect of the paper, but the overall study looks at a lot of recent historical data from the Northeast. I haven’t looked at it in detail yet, but it appears quite substantial.

    OK, this is a long comment already–especially for one that’s OT!–so I’ll stop.

    But clearly it’s not hard to find more support for Mike’s statement than just van Mantgem 2009. After all, this comment is the result of about half an hour’s searching by a rank amateur. And I’d love to hear what Mike Roddy has to say about the sources underlying his original comment. I bet there’s a lot more to be said.

  49. 49
    Ray Ladbury says:

    Dan H.,
    Oh, I’ve no doubt the court will side against the environment. The question is what we are doing by having the Supreme Court rule on a matter of physical reality.

  50. 50
    Rick Brown says:

    Kevin McKinney @ 48: I’ll respond briefly over on the Unforced Variations thread, which is where this belongs.

Switch to our mobile site