NASA-led Study Solves a Global Methane Puzzle


A new NASA-led study has solved a puzzle involving the recent rise in atmospheric methane, a potent greenhouse gas, with a new calculation of emissions from global fires. The new study resolves what looked like irreconcilable differences in explanations for the increase.

Methane emissions have been rising sharply since 2006. Different research teams have produced viable estimates for two known sources of the increase: emissions from the oil and gas industry, and microbial production in wet tropical environments like marshes and rice paddies. But when these estimates were added to estimates of other sources, the sum was considerably more than the observed increase. In fact, each new estimate was large enough to explain the whole increase by itself.

Scientist John Worden of NASA’s Jet Propulsion Laboratory in Pasadena, California, and colleagues focused on fires because they’re also changing globally. The area burned each year decreased about 12 percent between the early 2000s and the more recent period of 2007 to 2014, according to a new study using observations by NASA’s Moderate Resolution Imaging Spectrometer satellite instrument. The logical assumption would be that methane emissions from fires have decreased by about the same percentage. Using satellite measurements of methane and carbon monoxide, Worden’s team found the real decrease in methane emissions was almost twice as much as that assumption would suggest.

When the research team subtracted this large decrease from the sum of all emissions, the methane budget balanced correctly, with room for both fossil fuel and wetland increases. The research is published in the journal Nature Communications.

Fast Facts:

› Atmospheric methane concentrations are given by their weight in teragrams.

› One teragram equals about 1.1 million U.S. tons — more than the weight of 200,000 elephants.

› Methane emissions are increasing by about 25 teragrams a year, with total emissions currently around 550 teragrams a year.

Most methane molecules in the atmosphere don’t have identifying features that reveal their origin. Tracking down their sources is a detective job involving multiple lines of evidence: measurements of other gases, chemical analyses, isotopic signatures, observations of land use, and more. “A fun thing about this study was combining all this different evidence to piece this puzzle together,” Worden said.

Carbon isotopes in the methane molecules are one clue. Of the three methane sources examined in the new study, emissions from fires contain the largest percentage of heavy carbon isotopes, microbial emissions have the smallest, and fossil fuel emissions are in between. Another clue is ethane, which (like methane) is a component of natural gas. An increase in atmospheric ethane indicates increasing fossil fuel sources. Fires emit carbon monoxide as well as methane, and measurements of that gas are a final clue.

Worden’s team used carbon monoxide and methane data from the Measurements of Pollutants in the Troposphere instrument on NASA’s Terra satellite and the Tropospheric Emission Spectrometer instrument on NASA’s Aura to quantify fire emissions of methane. The results show these emissions have been decreasing much more rapidly than expected.

Combining isotopic evidence from ground surface measurements with the newly calculated fire emissions, the team showed that about 17 teragrams per year of the increase is due to fossil fuels, another 12 is from wetlands or rice farming, while fires are decreasing by about 4 teragrams per year. The three numbers combine to 25 teragrams a year — the same as the observed increase.

Worden’s coauthors are at the National Center for Atmospheric Research, Boulder, Colorado; and the Netherlands Institute for Space Research and University of Utrecht, both in Utrecht, the Netherlands.


94 thoughts on “NASA-led Study Solves a Global Methane Puzzle

      • Never knew that Fire produces Methane. I always thought that Fire acted to oxydize Methane.
        CH4 + (2)O2 = CO2 & (2)H2O
        The fact that Earth could have Fire was responsible for the Short Atmospheric Residence time of Methane.
        If fire can actually create Methane without oxydizing it is news to me.

    • Termites and healthy forests emit more CH4 than humans ever can. CH4 oxidizes to CO2 very quickly. In short, not a problem.

      • “Paul January 4, 2018 at 4:09 am”

        Just CO2. How one can class CO2 at ~400ppm/v as good or bad is beyond me.

      • lol assigning emotive moniker to a trace gas :D

        I see a bright future for this one in climate science, maybe with old Mark. “The Arctic is screaming” Serreze

      • Paul,
        Obviously, if the fire burns a tree, the CO2 released is GOOD CO2
        If the fire burns a house, car or other Man Made device that is BAD CO2

      • They fail to mention termites at all and they alone account for at least 4% of all sources.

        They likely also count all thermogenic gas as being from fossil fuel production and ignore that there are natural seeps of hydrocarbons all over the world. This is what they did for the four corners area of the U.S. where a large source of methane exists. They d-nye to acknowledge that the vast majority of methane is seeping from coal outcrops that have degassing for thousands of years.

    • Unlike methane, the origin of CO2 is isotopically identifiable… and its coming from fossil fuels, not forest fires.

      • Griff,

        As I have pointed out to you before, CO2 from fossil fuels would have a δ13C of circa -28 per mil and yet the change in δ13C of atmospheric CO2 reflects a value of -13 per mil. In addition, the δ13C of CH4 can also be linked to its source(s), as indeed is discussed in the paper.

      • Mark,

        The δ13C value (13C/12C ratio relative to a standard) is different. Currently, δ13C of atmospheric CO2 is roughly -8.5 per mil, while the value for CH4 is about -47.4 per mil.

      • Wrong. CO2 from soil respiration is 6x human production. Soil 13C -21PDB, human 13C -24PDB. The atmosphere 13C -8PDB. There is no way we can currently tell if an atmospheric 13CO2 molecule came from the 60gt soil respiration or the 10gt human combustion. The human isotopic signature is an SKS fantasy.

      • Griff,
        I’ve often been curious about just this.
        Can you link to the report/data indicating the isotopic differences between CO2 sources?

      • Oceans emit ‘fossil’ CO2 from deep in the oceans – source, deep ocean vents. There is literally no different in the deep ocean CO2 and fossil fuel CO2. Assuming that a rise in ‘fossil’ CO2 from coal combustion or natural gas, is an error. It can be from warming ocean waters that rise from the deeps to the surface. I agree that SKS’s claims about the human fingerprint is neither proven or even logically possible.

    • I just have a question about the video map: is that supposed to be a seasonal shift video, or is the permanent snow line simply starting to creep further south and nobody told me?

  1. So they use teragrammes as opposed to parts per billion? I guess teragrammes sounds so much more scary! When is NASA going to ditch pseudo-science and actually do some space science?

    • The mas of a quantity of matter is a far more appropriate metric for these data than the ratio of the quantity to, um, well, something outside the scope of the study. The proper metric is actually moles, but the conversion factor is 16.04 g/mol for methane if you have your slide rule handy and the conversion is understood by most people educated in science.

      Parts per billion would indicate the ratio of the number of moles of methane to the number of moles of all other gases in the atmosphere. You could derive that product from the basic data given plus some other estimates from other sources, but it’s less descriptive of the phenomenon under investigation and that sort of manipulation is more appropriate for publishing political rhetoric than for publishing a scientific result.

  2. Oh Brother! We don’t properly understand the methane cycle, including the bacteria that eat methane. WUWT Presumably the bacteria will increase in response to increased methane in the atmosphere. The variable bacteria population should put a limit on the methane concentration. They are even in the air and aren’t well understood. link I think Worden et al are deluding themselves if they think they’ve solved the problem.

    • Well, self-delusion does seem to be a favorite past-time among Uncle Shyster’s most loyal minions.

      • If we’re being honest, we have to admit that we all suffer from self-delusion.

        The first principle is that you must not fool yourself—and you are the easiest person to fool. So you have to be very careful about that. After you’ve not fooled yourself, it’s easy not to fool other scientists. You just have to be honest in a conventional way after that. Richard Feynman

  3. “The area burned each year decreased about 12 percent …”
    Oops, shouldn’t have said that! All the warmers are saying fires – California, USA, and the world – are increasing due to AGW.
    Oh, what to think!

    • “Phillip Bratby January 4, 2018 at 12:56 am

      The BBC (of course) covers the story, with the additional fake nonsense about “trapping heat”:
      “CH4 is about 30 times better than CO2, over a century timescale, at trapping heat in the atmosphere”.

      Traps heat for a century? WOW! Just ignore the laws of thermodynamics why don’t you BBC?

      • Patrick,

        The BBC long abandoned boring, factual news broadcasting for red top sensationalism, to competed with said red tops.

        It’s said than no news is good news. Wouldn’t it be refreshing for the BBC to one day announce “Today there is nothing worthwhile to report, so everything’s good with the world”.

        Two chances of that though.

      • In today’s world of sensationalism, if your news stories don’t induce anxiety attacks in your audience (among other things), you’ll probably be told you’re losing your touch and you should find another job. You have to get people upset enough to gossip about something, you see, unless they’re smart enough to do a little searching and get the facts for themselves.

      • HotScot,
        Would the Beeb be required to fill the their screens with Page 3 articles on slow news days??

    • I really think that no one knows very much about the methane cycle in the atmosphere and the effect that methane has on trapping heat .
      I have read so many different opinions that methane is up to 86 times more potent over 100 years than CO2 and there are many different numbers for the 20 year time frame starting at around 18 times and up over 30 times .
      I would like someone to show why there is a difference for 100 years and 20 years .
      If the half life of methane is say 12.5 years then all the amount that was emitted 25 years ago has been ( or the equivalent amount ) oxidized into CO2 and H2O so where does the 100 years calculation come from.
      There is also disagreement on the half life of methane in the atmosphere with researchers starting from as low as 8 years up to 26 years .
      I would expect with slowly building amounts that the half life would lengthen till the system comes back into equilibrium as it was from 2000 to 2008 when it should have been comparatively easy to do the calculation on the average methane residency in the atmosphere .
      At least these researchers were not zeroing in on farmed livestock methane emissions which I have stated before that live stock do not add any carbon molecules to the atmosphere as all fodder eaten by livestock has absorbed CO2 from the atmosphere and livestock are merely cycling the carbon molecules back to the atmosphere ,
      There is one carbon atom in a molecule of CO2 and the same amount in CH4 and over the lifetime of any methane emitted by livestock there can be no measurable effect.
      As the CH4 is oxidized into CO2 the Co2 is absorbed by plants and the cycle continues .
      Between 110 billion tonnes and 125 billion tonnes of methane is emitted each year from the burning of fossil fuels and every tonne has been extracted from beneath the earths surface and it is this amount that is slowly increasing the methane levels .
      The analogy that I have used is that you have a swimming pool with a pump and a filter .
      Now imagine that the atmosphere is the swimming pool and the livestock act as the filter .
      A filter at a swimming pool neither raises or lowers the level of the water in the pool and neither do the livestock raise the level of methane in the atmosphere .
      The livestock methane may take 25 years to cycle around but there is no ADDITIONAL methane or CO2 added to the ( pool) atmosphere.

      • In a way there is though as Livestock Breed and increase their numbers over time. Beef pricing is also up which tends to lead to a desired increase in herd size

    • The BBC… “CH4 is about 30 times better than CO2, over a century timescale, at trapping heat in the atmosphere”.

      Table 8.7 Page 714 of the IPCC’s AR5 report tells us that the Global Warming Potential of CH4 is 86.

      The text says:

      Metrics can be given in absolute terms (e.g., K kg–1) or in relative terms by normalizing to a reference gas — usually CO2. To transform the effects of different emissions to a common scale — often called ‘CO2 equivalent emissions’—the emission (Ei ) of component i can be multiplied with the adopted normalized metric (Mi): Mi×Ei=CO2-eqi.

      Somewhere in that gobbledygook it means that CH4 is 86 times more powerful than CO2

      What it doesn’t say is how much global temperature will rise in response to a particular increase in CH4. I’m rather sure that you can’t find that information anywhere. Why? Because it’s not very much that’s why. 86 times more powerful at trapping heat or just 30 as your Beeb source says is a scary statistic but in reality it’s a paper tiger. Methane is increasing at 6 or 7 parts per billion annually and by 2100 that might run global temperatures up a few 1/100ths of a degree. It really isn’t anymore than that.

      • SC: From your link, Table 8.7, the crucial factor depends upon the time scale chosen.

        CH4 is 86x or 34x or 70x or 11x depending upon the criteria to be cherry-picked

      • Reply to Bryan A
        See my post 8 down the page ‘
        Do the calculations your self
        10 percent more producing another 9 million tonne of methane makes a total of 9 9 million tonnes of methane emitted round that up to 100 million tonnes and global emissions then increase to 560 million tonnes and the livestock portion then rises to 18 percent of total emissions
        Taking Steve Zell’s figures he calculates that 12, 65 million tonnes has been added annually to the atmosphere in recent years..If we add the 10 million tonne on that is around 22,5 million tonne extra methane would be added to the to the atmosphere .
        This equals 180 percent increase the level of increase of methane in the atmosphere .
        0.00065 ppm multiplied by 180 % equals an annual increase of 0.00117 ppm per year and a increase of 0.117 part of a millionth in 100 years .
        This is adding every extra methane emission from 10 percent more global livestock from today and no allowance for any additional sinks .

      • Joe Public January 4, 2018 at 6:33 am
        SC: From your link, Table 8.7, the crucial factor depends upon the time scale chosen.
        CH4 is 86x or 34x or 70x or 11x depending upon the criteria to be cherry-picked

        As interesting as that is or isn’t, it tells us absolutely nothing about how much methane will run up global temperatures for any particular time period. So armed with the fact that methane is so many times more powerful than CO2 at trapping heat, in a business as usual scenario, how much will methane warm up global temperatures by the end of the century?

      • Thanks Gwan
        I misread your original point about Livestock being net zero CO2.
        But now, thinking about it, livestock could be carbon sinks rather than neutral.
        The fodder grows sinking carbon from both CO2 and oxidized CH4.
        Livestock eat the fodder but only return a small portion as CH4 the remainder helps the animal to grow.
        The animal is a sink until slaughtered

  4. GISS has sadly become a joke…

    Here are CAGW’s dire CH4 projections vs stubborn reality, which are off by an order of magnitude:


      • HotScot-san:

        I have absolutely no doubt NASA will come up with a “SCIENCE! (TM)” algorithm to “fix” CH4’s paltry observed values…

        They can’t just idly allow reality to interfere with their narrative of evil catastrophic manmade CH4 warming. That would be sacrilegious…

    • SAMURAI January 4, 2018 at 1:14 am
      GISS has sadly become a joke…

      Here are CAGW’s dire CH4 projections vs stubborn reality, which are off by an order of magnitude:

      The paper has nothing to do with GISS:
      Jet Propulsion Laboratory, California Institute for Technology, Pasadena, 91109, CA, USA
      John R. Worden, A. Anthony Bloom, Zhe Jiang & Thomas W. Walker
      Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands
      Sudhanshu Pandey, Sander Houweling & Thomas Röckmann
      SRON Netherlands Institute for Space Research, Utrecht, The Netherlands
      Sudhanshu Pandey & Sander Houweling
      National Center for Atmospheric Research, Boulder, 80301, CO, USA
      Zhe Jiang & Helen M. Worden
      Department of Earth Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
      Sander Houweling

      Also you don’t appear to understand what an order of magnitude is.
      “Orders of magnitude are used to make approximate comparisons. If numbers differ by one order of magnitude, x is about ten times different in quantity than y.”

    • The yearly methane emissions of 550 teragrams (= 550 million metric tonnes = 550 billion kg), at a molecular weight of 16.043, is equivalent to 3.43*10^10 kgmol/year.

      The total mass of the atmosphere can be estimated as 5.26*10^18 kg. Using an average molecular weight of 28.8, this is equivalent to 1.83* 10^17 kgmol.

      If all the emitted methane remained in the atmosphere, the methane concentration (mole fraction) would be increasing at a rate of (3.43*10^10) / (1.83*10^17) = 1.88*10-7 /year = 0.188 ppm/year.

      The graph posted by “Samurai” shows that actual methane concentrations increased from 1.71 to 1.80 ppm in 21 years, or 0.0043 ppm/year, or only about 2.3% of the rate predicted from methane emissions.

      This means that 97.7% of the methane emissions are being removed from the atmosphere by natural causes.

      What natural processes are removing over 97% of the methane emissions from the atmosphere? Instead of making dire predictions about methane concentration increases that are 2 to 5 times what was actually observed, shouldn’t the IPCC be investigating all these methane sinks to quantify how much methane is going where, and how much methane can actually be removed from the atmosphere by natural processes?

      • Thank you Steve Zell for your calculations above .
        Taking your calculations and estimations it becomes very easy to calculate :
        550million tonnes of methane emitted from all sources and the livestock portion is 90 million tonnes therefore just over 16.3 percent of global methane emissions come from livestock .
        We multiply the increase of 0.00043 ppm by 16.3% and we come up with the answer of 0.00007009 ppm increase of atmospheric methane concentration that can be attributed to livestock .
        We multiply by 100 years and the answer comes out at 0.007009 parts per million .
        As I have written in a post below methane emissions are a cycle .
        CO2 from the atmosphere absorbed by plants to grow fodder which is eaten by animals where a small portion of methane is emitted during digestion.The methane is oxidized in the atmosphere into CO2 and H2O and the cycle continues.
        Even if we accept that a small amount of methane from animals builds up in the atmosphere the amount that I have calculated with the help of Steve Zell’s figures is an minuscule amount over 100 years of an addition of 0.007009 parts per million which would warm exactly nothing .

  5. It sounds like they tried to do actual science this time at least. Measuring, using the billion dollars of instruments put into space, making logical deductions based on the evidence. This is what we have been asking for.

    • I don’t agree….using the same instruments they measured methane increasing….and decreasing
      Looks more like convenient curve fitting to me.

    • Long time since I did error analysis, but this does not seem right to me:

      “The CO-based fire CH4 emissions estimates amount to 14.8±3.8Tg CH4 per year for the 2001–2007 time period and 11.1±3Tg CH 4 per year for the 2008–2014 time period, with a 3.7±1.4Tg CH4 per year decrease between the two time periods.”

      Isn’t the error in the difference equal to the sum of the squares of the individual errors, i.e. 4.8Tg (provided the estimates are independent, otherwise greater still if partially/wholly dependent)?

  6. Agreed, Bill, but it doesn’t sound very convincing. We need to see the actual paper or at least the abstract – any links, anyone?

    In the meantime, the global representation seems to be rather bizarre. Is that no methane or no data over North Africa, Middle East and China? And what about the poles – atmospheric methane peaks in mid-winter (both hemispheres).

    For context, here are some actual measurements from Barrow (Alaska), Mauna Loa and South Pole (note units: parts per billion):

    So what about the increase in growth after 2006?

    The following NOAA plot shows the “uptick” in methane growth (annual variation not shown for clarity) as well as the decreasing δ13C-CH4 on a common datum for different latitudes. This avoids any need to address possible reasons for the offset in concentration from south to north, but it does highlight very well the globally synchronous nature of the change in growth rate.

  7. I wonder if NASA’s definition of methane emissions “from the oil and gas industry” includes natural seepages from undeveloped oil and gas deposits? As I am sure David Middleton can tell us oil explorers sniff out these to assist in finding such deposits.

    • I doubt it includes naturally occurring methane seeps. I also doubt that it’s an actual measurement. 17 teragrams per year “from the oil and gas industry” is probably an estimate of methane emissions from oil & gas production, transportation and refining. It’s probably based on an assumption about how much methane is emitted per barrel of oil and mcf of natural gas produced.

      As I understand it, their estimate of methane emissions from oil & gas operations is larger than the measured increase in atmospheric methane since 2006. Their estimate of methane emissions from wetlands/rice farming is also higher than the measured increase in atmospheric methane since 2006. The measured reduction in area burned by fire and measured reduction in carbon monoxide yielded a reduction in the estimate of methane emissions from fires. This estimate offsets some of the estimated emissions from oil & gas and rice farming and matched the rise in atmospheric methane.

      There are quite a few assumptions involved in this. But they aren’t unreasonable assumptions.

      • The methane emissions from the oil and gas industry are probably based on “fugitive emissions” estimates–leaks from flanges and valves. However, the factors used by the EPA (in g/day/flange) are usually at the high end of leak rates measured by “bag and sniff” methods (wrapping a flange or valve in an impermeable balloon, and measuring the methane content in the balloon after a set amount of time). So these emission estimates are based on multiplying the emission rate of the leakiest flanges by the number of flanges, and discounting the fact that most well-maintained flanges have much lower leak rates.

        This could lead to grossly over-estimating the methane emission rates from oil and gas operations.

  8. A couple of weeks back I was introduced to a student from Nigeria studying agriculture, including the climate. Of course I asked him how he reconciled the ‘war on CO2’ with any reasonable study of agriculture only be surprised when he replied that much more potent ‘greenhouse gases’ were more important, citing methane above all. Now I’m wondering if a switch from CO2 to methane isn’t in the making. Watch the pea under the pot…

  9. “Methane emissions have been rising sharply since 2006”
    is that newspeak for “we started measuring it in 2006” ?

    • No. See my graph above. The “puzzle” was (and still is) why did atmospheric growth stop from around 2000 to 2006, then start to rise again.

  10. It’s another simultaneous equation with multiple variables. They can only solve it by simply asserting that know each and every one with sufficient accuracy and precision. Neither is true. The numbers only add up because they make them so.

    Another analogy is national exports and imports. They never add up and the world apparently runs a trade imbalance with the rest of the universe. Econometricians are frequently honest enough to have a thing called the “balancing” figure in the budgets, which is simply the number they use to make the totals match. Climate scientists are less honest than economists.

    • Sounds like climate models. They are horrific on regional and continental scales, but look “reasonable” when looking only at global temperature anomalies, so they are portrayed as being realistic.

  11. Methane, huh? I knew I shouldn’t have let the mastodons stay in my back yard. And entire herd of mastodons and/or mammoths can produce gigatons of methane in a single week that completely throw off the scale.

    I’m very curious about why there is nothing related to thawing methane pockets in the Siberian wilderness. Those unexplained big holes were the result of the tundra easing past the melting point of frozen methane.

    Seriously, methane is a fuel source, so I don’t see what the real problem is, aside from the fact that it’s a flammable gas. Nor do I understand the point of this bit of research, other than to provide another molecule to pound on as a “bad gas molecule”. Does this mean that rice and beans may become forbidden foods? Just what are these people going to do about rice paddies and wetlands, anyway? Are they going to tell the populations of Asia that they can’t have the one vital staple of their diets any more?

    NASA throws this stuff in front of us, almost as a ‘Look! Panic!’ thing, and leaves it at that. It’s a naturally-occurring gas that exists everywhere on this planet, and they think they’ve solved a problem? I want to see them plug up volcanoes.

    This is ridiculous.

    • Yes, it is ridiculous. Supplies for the propaganda mill, and gotta use that grant money for something — use it or lose it.

  12. NASA does not understand methane emissions.

    My findings, natural gas, not just methane, show that natural gas upwells all
    around the earth, but it is not evenly destributed. In the presence of adequate
    moisture, it is consumed by microbes in the soil, enriching the soil as they oxidize
    the natural gas.

    The claim by many researchers that the hydrocarbons found in topsoil are absorbed
    from the atmosphere is incorrect. The claim is based on the paradigm that hydrocarbons
    are fossils.

    Dr. Gold and Mendeleve were right.

    The hydrocarbons are created deep in the earth, about the same depth as diamonds.
    They rise and some are trapped under layers of semi permeable or nearly impermeable
    shale. Some rise and hit the shield too close to the suface of the earth to find a way
    around it, and those areas have very poor topsoil. The area around Atlanta, Ga, USA
    is a good example of soil deprived of upwelling natural gas, so it has red clay.

    In areas where the hydrocarbons rise relatively unimpeded and there is adequate
    moisture to support the microbal culture, the topsoil is enriched according to
    the flow of hydrocarbons. eg Soils in Kansas and the Ukraine get lots of gas.

    I have proved the upwelling of hydrocarbons below the topsoil part. Based on my
    research and study of other people’s work, I hypothise;

    1.The gentle warming of the earth’s crust speed the upwelling of the deeply
    formed gas. This accounts for the slow rise in the amount of methane measured in
    the atmosphere and atmospheric CO2 levels following tempereture rise.

    2.The reduction in the speed of the rise of atmospheric methane of late is one
    or both of two possibilities.
    A. The greening of deserts allows the microbal culture in the soil in
    these areas to consume the hydrocarbons heretofore passing unaltered
    into the atmosphere.
    B. The wildfires heat the soil enough to temporairly kill the microbal
    culture and temporairly increase the amount of unoxidized hydrocarbons
    rising into the atmosphere.
    3. A reduction in world wide wildfires and a decrease of atmospheric hydrocarbons
    and a subsequent increase of wildfires and an increase in atmospheric hydrocarbons
    argues for B. I will do heat experiments on the microbal culture in topsoil
    and test the results for CO2 output/hydrocarbon output.
    4. My experiments do not show fire producing methane.

  13. Proof that the methane cycle is still not well understood. Where is all that “settled science” I keep hearing about?

  14. More support for my comments above.

    I disagree with this article only in that in my view, there is no limit. Carbonates
    are being constantly fed into the hydrocarbon creation zone via subduction
    at the tethonic plate margins. There is plenty of iron oxide and water, etc to
    create a constantly replenishing process and as pressure is relieved above,
    more perks up.

  15. I do have doubts about the alleged long life of methane in the atmosphere. Methane is flammable, and even though the concentration is less than the LEL, it must surely be ignited and burnt as a result of every lightning stroke. Given the prevalence of thunderstorms, surely the life of methane in the atmosphere must be in the order of weeks rather than years?

  16. We are reminded “ad nauseum” that methane is a potent greenhouse gas and while 1,900 ppb sounds like an awfully big number, it’s equivalent to a bit less than 2 cents in $10,000. What? Me worry?

  17. “We found a possible explanation….” seems to be the only conclusion that can reasonably be drawn from this report. They have not ‘solved’ the ‘puzzle’ at all. Possibilities are not rigorous solutions.

  18. This paper amounts to “it’s possible our guess (where the new methane came from) is right”.

    PS: I think methane is likely a pathetic greenhouse gas because all the absorption it can do will already be done by water; and there’s a lot more water in the atmosphere. [ because the O — H (in water), and C — H (methane) sigma bond absorptions will show up at similar spectra ]

  19. I agree with J Mac and Mark Pawelek about it being a “possible” explanation. The paper was, in my view, an attempt to counteract a number of papers that have concluded that the δ13C data actually support a biogenic source for the increasing CH4 since 2006/7 and there was a desire to point the finger at fossil fuels. There is actually quite a helpful summary of the state of knowledge published by NOAA in July 2017:

    As NOAA states:
    “That drop [in δ13C] casts doubt on one of the first explanations experts considered for the post-2007 rise: an increase in methane emitted from fossil fuels, including “fugitive” methane gas escaping during oil and natural gas drilling. Instead, the chemical fingerprints point toward agricultural and wetland emissions from the tropics.”

  20. What we are meant to believe here is that from 2000 to 2006, the sink(s) happily matched the emissions, including those from fires. Then, all of a sudden (at all latitudes, see the NOAA graph I posted above), the fossil fuel and the wetland emissions started to rise above what the sink(s) could handle and at the same time fires immediately reduced so the the growth rate then matched their presumed emissions/sink levels. Clearly a very convenient coincidence.

  21. Who cares? GHG driven warming is a nothing. Methane variation is a nothing. All advances in scientific understanding are nice but the only reason research funds are pouring into this area is the utterly phony global warming alarmism.

  22. The article states that “that about 17 teragrams per year of the increase is due to fossil fuels, another 12 is from wetlands or rice farming”

    Doesn’t this imply that rice farming etc. are increasing year to year, and not remaining constant? Otherwise, there would be no “increase due to rice farming,” as it would be responsible for more or less the same emissions each year.

  23. My summary of the article:
    Climate scientists have assumed there are three sources of CH4 in the atmosphere and made guesses about the rate of emissions for all three. Others noticed the sum of the guesses did not match reality. We found a way to change one of the guesses so the sum is the same number as today’s reality, and without having to reduce the politically important guess..

  24. “more than the weight of 200,000 elephants”

    Africa elephants Indian elephants? Male elephants or female?

    Does the iSO know about this new standard of mass, where are the standard weights kept?

    • This standard of mass is kept in Melbourne, where one tram = 42 Rhinos.

      If you get hit by one tram, it is the same as being hit by 42 Rhinos!

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