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What is methane's contribution to global warming?

What the science says...

While methane is a more potent greenhouse gas than CO2, there is over 200 times more CO2 in the atmosphere. Hence the amount of warming methane contributes is 28% of the warming CO2 contributes.

Climate Myth...

It's methane


"A United Nations report has identified the world's rapidly growing herds of cattle as the greatest threat to the climate, forests and wildlife. ...


...Livestock are responsible for 18 per cent of the greenhouse gases that cause global warming, more than cars, planes and all other forms of transport put together.


Burning fuel to produce fertiliser to grow feed, to produce meat and to transport it - and clearing vegetation for grazing - produces 9 per cent of all emissions of carbon dioxide, the most common greenhouse gas. And their wind and manure emit more than one third of emissions of another, methane, which warms the world 20 times faster than carbon dioxide." (Geoffrey Lean)


While methane is a more potent greenhouse gas than CO2, there is over 200 times more CO2 in the atmosphere. Eg - CO2 levels are 380 ppm (parts per million) while methane levels are 1.75ppm. Hence the amount of warming methane contributes is calculated at 28% of the warming CO2 contributes. Here is a graph of the various forcings that influence climate (methane is CH4, right above CO2).

This is not to say methane can be ignored - reducing methane levels is definitely a goal to pursue. The good news is since the early 1990's, the trend in increasing methane has slowed down and even leveled off in the last few years (Dlugokencky 2003).

Atmospheric Methane Concentration

Last updated on 26 October 2016 by John Cook. View Archives

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Comments 1 to 50:

  1. Re: "This is not to say methane can be ignored - reducing methane levels is definitely a goal to pursue. The good news is since the early 1990's, the trend in increasing methane has slowed down and even leveled off in the last few years (Dlugokencky 2003)." Gee, what a coincidence!
  2. It would be better if the graph went back somewhat more than 20yrs. Preindustrial concentrations are estimated around 700ppb, just 40% of modern concentrations. Much of the rise has to do with population increase and dietary habits. Population increases in the east have demanded increased rice production and the consequent increase in methane emission. Western diets are highly biased to meat consumption resulting in huge growth in ruminant numbers since 1960, another large methane source. Also, I am not too sure if the overall effect of methane is included in models? Methane breaks down into water and CO2 and I would expect the total GG effect of methane to include the secondary effect of these. I recently read that global methane emissions is on the rise...will have to find that paper again........
  3. Note: Methane intially reacts with ozone in a 'chain' reaction that ultimately produces CO2 and water vapour. You could summarise the reactions into: (3)CH4 + (4)O3 = (3)CO2 + (6)H2O Oxidation of methane is the main source of water vapor in the upper stratosphere
  4. The question is not about what's in the atmosphere, but about what humans are responsible for emitting. Maybe there is a lot more CO2 in the atmosphere than methane, but what percentage of each those gases are human activities responsible for? Historically(averaging over the past 400,000 years) CO2 is around 240ppmv, and now it is around 385ppmv(60% higher). Methane is historically(over past 1,000 years) around 700ppb and now at 1700ppb(140% higher). The % for CO2 is smaller if we start from the warm period average of around 280ppmv. While the sheer volume of human released carbon dioxide and its warming affects probably are far greater than that of human released methane, humanity seems to have changed the concentration of atmospheric methane much more than that of carbon dioxide. The fact is that changes in agriculture and diet are the easiest way for an individual to lesson his or her environmental impact. Local, organic, and vegetarian diets are a simple highly effective remediation strategy. Disclosure: I am a vegetarian and so strongly biased on this particular issue, but this point cannot be ignored. sources:'s_atmosphere
  5. "Hence the amount of warming methane contributes is calculated at 28% of the warming CO2 contributes" Does the first graph relate to the relative historic influence of each greenhouse gas emission to the radiative forcing we experience today? If so do we really need to know the relative effect of each greenhouse gas we emit today projected forward onto a certain timeframe to establish their real importance? Either way the graph needs to be clarified and referenced
  6. Methane concetrations have stalled int the atmosphere since approximately 1998. Have scientists figured out why? And is melting permafrost contributing enough methane to significantly raise its concentration in the atmosphere yet?
  7. Karmanski @6, That graph needs to be updated: [source:]
  8. Does anyone have a reference that supports the Methane is 21 times CO2 thesis? I have seen this figure referenced all over the internet, but I haven't seen how it is calculated.

    [DB] Recent topical discussion on Methane over at Tamino's.

    Chris Colose, Eli Rabett (and also here) and Steve Bloom all weigh in with good points.

  9. AndyS the claim that CH4 is "more powerfull" than CO2 is a bit ambiguos. It's not clear to what it refers. I suggest a good discussion on this topic at Chris Colose site.
  10. I wonder if someone could clarify a point for me? When sceptics say "you'll have to stop breathing then, because you're exhaling CO2" I point out that animal respiration is just part of the natural carbon cycle, (circulating 400Gt of CO2 a year), and that any carbon we breathe out was first captured from the atmosphere through photosynthesis to enter the food chain. Cow burps are treated differently however, and are seen as part of the problem. Is that because the carbon from the plants going through the cow is being converted (in part) to the more greenhouse active CH4, rather than merely being returned as CO2? (I realise cattle have a broader greenhouse footprint because of transportation and energy used in grain cultivation and so on, but I'm just curious about the methane here.) Many Thanks.
  11. Crispy, my understanding is that the accounting for methane is based on effect that methane has before it is oxidised to CO2 compared fate of plant carbon if it hadnt been eaten by ruminant. You might like to look up the GWP (global warming potential) for more detail.
  12. 1. Authors of super-freakonomics have said that eating kangaroo meat as opposed to a ham-burger is good for climate as methane is a greater threat! Is that scientifically correct? 2. Same book mentions that methane is 25 times more potent than CO2 as greenhouse gas. If CO2 level is 200 times CH4 how does it contribute 28% warming than CO2? (I am assuming law of proportions to hold. Correct if wrong) 3. Will emitting sulpher in atmosphere help cooling the planet? After what altitude exactly does sulpher cease being trouble (acid rain etc..) Thanks!
  13. Hi, abhi541. 1. I have no idea, but someone here might. 2. See this thread and the comment stream that follows it. 3. See this thread. Post further questions on the relevant threads.
  14. abhi541 1) i didn't know about kangaroo meat. A quick search led me here. Apparently there's some merit in eating this meat. 2) Methane is some 25 times more potent on a molecule by molecule basis, though the effect, i.e. the forcing, is not proportional to concentration. 3) sulphate aerosols have a cooling effect. In a geo-engeneering framework, you want them in the stratosphere. Sorry for the short and schematic answer. Follow DSLs suggestion, maybe someone else will give you more details, assuming you want more :)
  15. 1/ I have heard this too. Kangaroos (and rabbits) are not ruminants so methane/kg-human-product is less than sheep/cattle. Kangaroos requires less processing than rabbit but are challenging to farm to say the least.
  16. Is there any research into estimating what percent each of the greenhouse gases is due to anthropomorphic activity? If the intent is to stabilize the concentrations of greenhouse gases it would be nice to know how much of an effect our actions have on each molecule. IE is there a study that shows us what policy will give us the most bang for our buck?
  17. 16 - Heircide Have a look at the wedges
  18. It seems to me that we have an opportunity to make serious reductions in methane emissions by using bio-digesters for most of our organic waste. Nearly all living things release methane as they decay. When our farm waste rots in the fields or our sewage decays in a treatment plant, most of the methane generated is released to do its damage. If we offer carbon credits at the rate of 21 pounds of CO2 to 1 pound of methane removed from our emissions, we would make methane production for fuel a profitable enterprise. Of course methane is basically natural gas, which is plentiful right now in the USA. There are, however, considerable benefits to making methane from our organic waste. A very significant one is the compost and fertilizer produced in the process. This adds fertility to our soils to help bring them back to life after years of pesticides and artificial fertilizers. The natural fertilizer byproducts of microbe digestion contain all of the micro-nutrients removed by the plants that were composted. The added organic material also allows our soils to support normal soil enhancing worms and insects like the common earthworm. As an important benefit, these organic elements will also help our soils retain moisture in the hot dry weather we seem to be creating by our bad habits. What do you think about giving power plant carbon credits for capturing methane? They could burn the methane also to assist in power production or sell it for transportation fuel. Should we encourage natural gas conversion for our cars and trucks? It could really have a low carbon footprint if the methane comes from micro-digester production by the power companies. At the present time around 50% of our natural gas is used to make artificial fertilizer. I understand that we can convert most cars to run on natural gas for under $1000. (That could employ a couple of hundred thousand people.) If the government wants to invest in infrastructure that will pay dividends into the long term future, why not build a natural gas distribution system? (Another couple hundred thousand jobs.) Our need for imported petrolium products would decline sharply and keep considerable fund here in the USA to finance needed investments. It is possible to affect methane levels if we look at data from China. They claim to have a 9% reduction in methane emissions in the last 5 years. The rice production has also gone up considerably from the use of the byproduct fertilizer from the process.
  19. Methane levels started to increase again, about 6 or 7 years ago, so this explanation needs updating.

  20. the more important point is that agriculture itself (minus land-use issues, transportation, pesticides, etc) should be carbon neutral, in the long run. the methane only takes a few years to decay back into c02, and then it gets recycled. if you ignore the transportation, and you take the pesticides out, and you offset the land-use with new planting, there isn't a net increase - it's just a redistribution from the soil to the trees, which can then be pulled back to the soil.

    this argument is still floating around. that's the key point in combatting it: the only net source of carbon into the atmosphere is from underground, that is fossil fuels. organic farming with proper offsets for clearing is (excluding transportation issues) actually carbon neutral in the long run.

  21. So, you are saying why Carbon-Soil Initiatives will never be an accepted method to combat climate change?!!?

  22. Deathtokoalas - that's a lot of factors you're asking us to ignore, and they are factors that are not being dealt with so I'm not sure why we should ignore them.  What matters it the current impact of agriculture, not what it could be if we wished away various aspects of it, wouldn't you say?

    Your argument is misleading.  Increased rumination due to our apetite for animal flesh puts methane and the resulting CO2 and water vapor into the atmosphere.  This is the bottom line - as long as these animals release gas, this will remain true.  Where would the constituents of methane be if they were not being farted out?  They would be in trees that would be, on net, absorbing CO2 instead of releasing it.  When the trees die, their carbon returns beneath ground (unless we burn the wood).

    So the effect of clearing massive swathes of forest (which is not being offset by replanting), plus pushing carbon from plant growth into methane and up into the atmosphere, is not neutral at all... or am I missing something?

  23. I've done some calculations and got to the following point and would like someone please to tell me where I've gone wrong.

    My question is "what are the relative contributions of greenhouse gases to the excess heating we experience this year?"

    Firstly, for excess we need to take the difference from pre-industrial levels, so CO2 is (2011 levels) 391 - 278 = 113 ppm and for methane is 1.803 - 0.7 = 1.103 ppm.

    Second is the rel warmoing potential which for CO2 is 1 and for methane over a 100 year period is 28. But that 28 is because methane progressively breaks down in to CO2 so for the last 50 years or so most of the methane has disappeared. To calculate the warming potential of methane right now I took the 100 year number, the 20 year number of 84, took logs and extrapolated back to 0 to get a native number of 110.


    contribution from CO2 = 113 x 1 = 113

    contribution from CH4 = 1.103 x 110 = 121

    Hence the extra warming generated this year comes slightly more from methane than from CO2.

    I've tried to work out what is wrong with this but have failed. Can anyone help?



  24. @23 Dipper:
    Your math seems to be correct!

    I think the problem is that the warming potential for CO2 vs. methane compares units of mass while your calculation compares units of volume.
    CO2 is 2.75 times heavier per molecule (or ppm) than methane, so the numbers for methane have to be divided by that if you are comparing the climate impact from each on a ppm basis.

    Doing that, you get these results for methane vs. CO2:
    100 years: 28 / 2.75= 10.2
    20 years: 84 / 2.75 = 30.5
    Instantly: 110 / 2.75 = 40

    And from pre-industrial to 2011:
    CO2: 113
    Methane: 121 / 2.75 = 44

    This figure shows the annual growth of forcings from the well-mixed greenhouse gases after 1950. Since the late 1990s the contribution from non-CO2 has only been about 20-25 %, but that fraction was up to 50 % until the early 1990s. Note that the methane forcing nearly stabilized in the early 2000s, but has started to increase again.

    Forcing growth rates

  25. Dipper @23, the Global Warming Potential is defined by the IPCC as follows:

    "Global Warming Potential (GWP) An index, based on radiative
    properties of greenhouse gases, measuring the radiative forcing following
    a pulse emission of a unit mass of a given greenhouse gas in the presentday
    atmosphere integrated over a chosen time horizon, relative to that of
    carbon dioxide. The GWP represents the combined effect of the differing
    times these gases remain in the atmosphere and their relative effectiveness
    in causing radiative forcing. The Kyoto Protocol is based on GWPs
    from pulse emissions over a 100-year time frame."

    You will notice that, first, the GWP is a function of mass, not volume (as pointed out by HK @24); and, second, that it is a function of emitted mass, not atmospheric concentration.  

    If you want to calculate the relative effect from atmospheric concentrations, you just use the formula for radiative forcing.

    Thus, for CO2, the formula is 5.35 x ln(C/Co), which for the values you give is 1.82 W/m^2.

    For Methane, the formula is ΔF = 0.036(M½ - Mo½) - [f(M,No) - f(Mo,No)]

    where f(M,N) = 0.47ln[1 + 2.01x10-5 (MN)0.75 + 5.31x10-15M(MN)1.52] and M stands for a Methane concentration, and N stands for a Nitrogen Oxide concentration.

    Ignoring the Nitrous Oxide adjustment, and using your figures, this yields Methane forcing of 0.02 W/m^2, or 1/91st of the forcing due to CO2.  There is a further, small adjustment due to the relative effectiveness of different forcings but it does not bridge the gulf in the relative impacts between the two.  The result is that, per unit concentration, methane is approximately 12% more effective at warming than CO2 at near current cocentrations, but the significantly larger increase in CO2 concentration means that CO2 is the primary warmer.

  26. Tom Curtis @25,

    That CH4 forcing cannot be right.

    Rather than test my own arthmetical skills, there is a year-by-year table 1979-to-date for the various GHG forcings is given by ESRL on that very page you link to. For 2015, CO2=1.939 Wm^-2 & CH4=0.504 Wm^-2.

    Mind, the global temperature increase since pre-industrial times (I assume this is Dipper's "excess heating we experience this year") results from the whole bucket of GHGs. If the analysis includes them all, CO2 & CH4 are only 82%. And if we are to consider that forcings of past emissions continue to operate, different GHGs have quite different concentrations histories.

    So, Dipper @23.

    How sophisticated do you want to get?

  27. Sincere thanks to HK, Tom Curtis and MA Rodger for responding so quickly and thoroughly. Lots of stuff for me to go and read up on. My simple calculations clearly not what is needed. Much appreciated!

  28. MA Rodger @26, thankyou for the correction.

    Redoing the calculation using CH4 concentrations expressed in part per billion (ppb) rather than ppm, ie, the typical unit used to express CH4 concentrations, I obtain a forcing of  0.576 W/m^2, with the remainder of the difference being due to my leaving of the NO2 correction.  Clearly the units used is critical in this equation. 

  29. When I consider the spirit that John Cook started this page; it seems you halted on animal prodcution (both your pages which touch on animal agriculture is a bit hindsighted, and it seems strange to have them seperated instead of just having one article on animal agriculture). This is indeed a climate science page, but you fail to take into account the potential CO2 mitigation by converting animal agricultural land to e.g., forests, or other crops that bind carbon to the soil.  You also don't take into account future projections of climate impact from this sector. Which is the real suprise to me.

    The projection in increased CH4 due to animal prodcution shows a great increase (1).
    From (1) "We suggest that, by 2050, the livestock sector alone may either occupy the majority of, or significantly overshoot, recently published estimates of humanity’s “safe operating space” in each of these domains."

    By 2050 we will also expand our agricultural land by more then 1 billion hektars (2). The situation is dire, and you guys, for once, don't promote looking a head in time. I'm baffled, maybe even shocked. This 1 billion hectar isn't going to come from deserts. Its going to be carbon binding areas.

    If china picks up a american diet they alone increase the production of animal products by 30 % (3).
    All in all, the projections of climate impact from the agricultural sector is increasing not decreasing or stabalizing. One of the major contributers is CH4. To me, your articles on animal agriculture are close to red herring with a touch of a nirvana fallacy. Red herring because you only evaluate the past, and don't look ahead. Nirvana fallacy because it is not a silver bullet, and that you don't take into account the relative change of emissions.
    Correct me if I'm wrong but, it is still true that animal agriculture has bigger emissions than all of transport combined---so why is it in your myth section?





    [DB] Your claims are best addressed on this thread.  Please read that thread and the comments in their entirety.  If you still have questions, place them there.  Thanks!.

  30. To add to my previews comment, I wonder if you have had a look at recent research by Susan Solomon involving methan (1)?
    It seems that we have underestimated the effects of short-lived GHG's.


  31. When will you update this nonsense that CH4 is not increasing anymore?
    As it definetly is:

  32. Let's look at atmospheric methane levels, shall we?

    First, we see that overall levels of atmospheric methane are indeed rising:

    Atmospheric methane

    We can also look at the global methane budget:

    Global methane budget

    We can even look at atmospheric levels of methane by latitude band:

    Methane by latitude

    From the available evidence, we see that the primary sources of the recent rise are from the tropics and mid-latitudes of the Northern Hemisphere, with some further contributions from animal agriculture and fugitive emissions from industry.  

    Doubtless further research will elucidate better quantifications.

    Your contributions from Zickfeld et al (not Solomon) are noted.  But the sheer size of the bolus emissions from CO2 have multi-millennial consequences, too:

    Per Zhang and Caldeira 2015, when you burn a lump of coal or some gas, the greenhouse effect from the resulting CO2 will over time warm the Earth 100,000 times more than the heat released upon combustion.

    (1 min video on their new study comparing CO2 and direct thermal warming from fossil fuels)

    At the end of The Long Thaw, David Archer calculates that the amount of energy that is trapped by the CO2 produced by burning gasoline today is, over its atmospheric lifetime, 40 million times the amount of fuel energy released today.

    "The lifetime of fossil fuel CO2 in the atmosphere is a few centuries, plus 25 percent that lasts essentially forever. The next time you fill your tank, reflect upon this. The climatic impacts of releasing fossil fuel CO2 to the atmosphere will last longer than Stonehenge," Archer writes. "Longer than time capsules, longer than nuclear waste, far longer than the age of human civilization so far."

    "The effects of carbon dioxide on the atmosphere drop off so slowly that unless we kick our "fossil fuel addiction", to use George W. Bush's phrase, we could force Earth out of its regular pattern of freezes and thaws that has lasted for more than a million years."

  33. The 'Solomon' paper you obliquely reference is found here:

  34. The sources that explain the rise of methane in the atmosphere, its dangers, why graphs need to updated to explain escaping methane from fracking pipes:

  35. I would like to see this updated with more data on arctic methane releases, including the Siberian methane explosions, as well as the methan hydrate outgassing from the ocean floor. I want to know how soon we might reach the point where the amount of methane already released would cause enough warming to ensure the release of all the frozen sources. 

  36. "more data on arctic methane releases, including the Siberian methane explosions"

    Here you go:

    "It would take about 20,000,000 such eruptions within a few years to generate the standard Arctic Methane Apocalypse that people have been talking about."

  37. The remainder can be split into 2 buckets:  Terrestrial (land-based) carbon sources and Marine (maritime-based) carbon sources.

    Land-based permafrost is indeed melting, reducing in both area and volume. However, the vast majority of carbon emissions from those land-based melting permafrost areas are in the form of carbon dioxide, not methane.

    There is an extensive amount of published research on the subject of GHG emissions from warming land-based permafrost and the possible releases from seabed methane clathrates in the Arctic. Let's look at land-based warming permafrost GHG emissions first...

    Per Gao et al 2013 - Permafrost degradation and methane: low risk of biogeochemical climate-warming feedback

    "Climate change and permafrost thaw have been suggested to increase high latitude methane emissions that could potentially represent a strong feedback to the climate system. Using an integrated earth-system model framework, we examine the degradation of near-surface permafrost, temporal dynamics of inundation (lakes and wetlands) induced by hydro-climatic change, subsequent methane emission, and potential climate feedback.

    We find that increases in atmospheric CH4 and its radiative forcing, which result from the thawed, inundated emission sources, are small, particularly when weighed against human emissions. The additional warming, across the range of climate policy and uncertainties in the climate-system response, would be no greater than 0.1° C by 2100.

    Further, for this temperature feedback to be doubled (to approximately 0.2° C) by 2100, at least a 25-fold increase in the methane emission that results from the estimated permafrost degradation would be required.

    Overall, this biogeochemical global climate-warming feedback is relatively small whether or not humans choose to constrain global emissions."

    And, as the Gao et al paper I linked to notes, CH4 from permafrost will drive an expected temperature increase by 2100 of about 0.1 C. Schaefer et al 2014 now calculates a total temperature rise contribution from ALL permafrost carbon stocks (CO2 AND CH4) by 2100 of about 0.29 ± 0.21 (0.08-0.5 C).

    Schaefer et al 2014 - The impact of the permafrost carbon feedback on global climate


    Per Schuur et al 2015, an abrupt permafrost climate feedback is unlikely, according to the experts, but the bad news is that the already difficult task of keeping warming under 2°C becomes much harder once we face up to the consequences of Arctic permafrost feedbacks.

    Per Sweeney et al 2016 - No significant increase in long-term CH4 emissions on North Slope of Alaska despite significant increase in air temperature


    "Data show no sign of methane boost from thawing permafrost"


    "Decades of atmospheric measurements from a site in northern Alaska show that rapidly rising temperatures there have not significantly increased methane emissions from the neighboring permafrost-covered landscape"


  38. Now let's examine the literature on Arctic seabed clathrate/methane emissions:

    Dmitrenko et al 2011 - Recent changes in shelf hydrography in the Siberian Arctic: Potential for subsea permafrost instability

    "the observed increase in temperature does not lead to a destabilization of methane-bearing subsea permafrost or to an increase in methane emission. The CH4 supersaturation, recently reported from the eastern Siberian shelf, is believed to be the result of the degradation of subsea permafrost that is due to the long-lasting warming initiated by permafrost submergence about 8000 years ago rather than from those triggered by recent Arctic climate changes"


    "A significant degradation of subsea permafrost is expected to be detectable at the beginning of the next millennium. Until that time, the simulated permafrost table shows a deepening down to ~70 m below the seafloor that is considered to be important for the stability of the subsea permafrost and the permafrost-related gas hydrate stability zone"


    Berndt et al 2014 - Temporal Constraints on Hydrate-Controlled Methane Seepage off Svalbard

    "Strong emissions of methane have recently been observed from shallow sediments in Arctic seas...such emissions have been present for at least 3000 years, the result of normal seasonal fluctuations of bottom waters"


    James et al 2016 - Effects of climate change on methane emissions from seafloor sediments in the Arctic Ocean_A review

    "We find that, at present, fluxes of dissolved methane are significantly moderated by anaerobic and aerobic oxidation of methane"


    "Our review reveals that increased observations around especially the anaerobic and aerobic oxidation of methane, bubble transport, and the effects of ice cover, are required to fully understand the linkages andfeedback pathways between climate warming and release of methane from marine sediments"


    "a recent study [the earlier mentioned paper by Dmitrenko et al in 2011] suggests that degradation of subsea permafrost is primarily related to warming initiated by permafrost submergence about 8000 yr ago, rather than recent Arctic warming"


    Per Myhre et al 2016 - Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere

    "Methane gas released from the Arctic seabed during the summermonths leads to an increased methane concentration in the ocean. But surprisingly, very little of the climate gas rising up through the sea reaches the atmosphere.

    As of today, three independent models employing the marine and atmospheric measurements show that the methane emissions from the sea bed in the area did not significantly affect the atmosphere."


    Ruppel and Kessler 2017 - The interaction of climate change and methane hydrates

    "The breakdown of methane hydrates due to warming climate is unlikely to lead to massive amounts of methane being released to the atmosphere"


    "not only are the annual emissions of methane to the ocean from degrading gas hydrates far smaller than greenhouse gas emissions to the atmosphere from human activities, but most of the methane released by gas hydrates never reaches the atmosphere"


    To sum, the vast majority of warming land-based permafrost GHG emissions are in the form of carbon dioxide, due to natural factors that help break down any methane releases into various components plus carbon dioxide (methane is much less stable than carbon dioxide).

    Similarly, the vast majority of gases expelled from degrading seabed methane clathrates are oxidized in the water column and do not reach the surface. Further, much of what we do measure in the form of existing releases are traced to the much longer warming present earlier in the Holocene. And that these same clathrates survived earlier interglacials, wherein global temperatures exceeded those of today...for millennia. So they are actually pretty stable.

  39. Baraliuh @29-31, has there been any resolution to your questions on Animal Agriculture?

  40. Baraliuh @29-31, here's a recent Nature article showing the enormous carbon sequestration potential of grasslands returning to native forests:

  41. In recent years, atmospheric methane concentration has increased again. It has been reported that "if you leak more than 2 or 3 percent [of methane] it’s worse for climate change than coal", so I checked Google Scholar to find out whether U.S. fracking might be why methane increased. In short, the answer is no. Nisbet et al. (2016) says

    "since 2007, growth has resumed, with especially strong growth in 2014. Evidence from carbon isotopes implies that the primary cause of the new growth is an increase in biogenic emissions, probably from wetlands and also agricultural sources, such as rice fields and cattle. The evidence presented in this research study, from a wide range of measurement sites both in the northern and southern hemispheres, suggests increased tropical emissions, for example from tropical wetlands, may be a principal cause of the global rise in methane. Contributions to the growth may also come from agricultural sources and perhaps some fossil fuel emissions also."

    But people should realise that CO2 builds up in the atmosphere, so natural gas still causes global warming even though it emits less CO2 than coal.

  42. Perhaps someone here can help me to clear up some confusion about methane and the Arctic. No one seems to be asking the question I have.

    OK, I got the memo: I'm supposed to be freaked out because arctic thawing is going to release methane from the clathrates on the continental shelf. A little red meat for you: Shahkova, Wadhams, Beckwith, others. They're the ones that seem to be screaming the loudest about this.

    Let's not get into the deep clathrates, or the land permafrost, as those releases are going to be pretty slow anyway. I'll stick to the clathrates on the Arctic Ocean continental shelf, which are shallow enough to be released quickly. Supposedly.

    The problem I have with all this talk is simple. The claim is that the global warming we're going to have (depending on whom you ask, either by 2100, or sooner, or even already) is going to cause a catastrophic release of methane from clathrates at shallow depths, where it can warm more quickly because it's really cold at those high latitudes. And we're told that this amounts to hundreds of billions of tonnes of carbon.

    Well, it's also well known that the Earth's gas, oil, and coal was laid down over the last 500 million years or so; more at some intervals than others, but overall, over hundreds of millions of years. Now, during the last 400 to 500 million years, the Earth has often been warmer than now, by several degrees C. In fact, the Earth has been in this "hothouse" condition for most of that time.

    Then, if it's true that a warming of a couple of degrees C, or even say 6 degrees, is enough to release a big part of this stored gas catsatrophically, within a few decades (some, apparently, think within a matter of years), then how is it that there is even any methane left at all? It should have all been released long ago. In particular, that especially nasty time, about 250 million years ago, when all that H2S came out of the stinking ocean, should have eliminated all of the clathrates at that time.

    Sure, some clathrates could have formed later, but if so, how could those amount to more than all the coal and oil, as some are saying?

    For me, this doesn't add up at all.


    [DB] You seem to be exposed to misinformation.  Please read this post on methane clathrates and put any relevant comments on the subject there, not here.

    "Shahkova, Wadhams, Beckwith, others"

    Claims made in the media are basically irrelevant.  Science is not an agenda to be prosecuted in the media.

    Lastly, this is an evidence- and science-based venue.  The burden is on the user (you) to support contentions and claims with citations to credible sources.  Preferably when you make them or, at the bare minimum, when asked.  Please read the Comments Policy and ensure that all comments comply with it.  Thanks!

  43. mondosinistro - I have further responded on the topic indicated by the moderator.

  44. I found this page because I was looking for an authoritative answer to the question "Is methane a more effective driver of climate change than CO2 (as I have believed since 1980), and if so by how much?". I don't feel any wiser. It seems clear that the answer is "yes" but the "how much" lacks agreement. What's the latest best guess, or range of such?
    I want this because the municipal authority where I live plans to withdraw facilities for composting garden waste and replace them with kerbside collections which go to landfill. On the logic that organic waste in landfill generates methane, this plan seems insane and I want a reliable datum to say just how insane.

  45. Richard Bramhall @44,

    The magic term you seek is "Global Warming Potential" (GWP) which is a measure of the resulting AGW caused by emissions of a gas by-weight relative to the warming caused by the same weight of CO2=1. As methane is less long-lived in the atmosphere, the GWP of methane depends on the length of your assessment period, the two period-lengths usually used being 20 years & 100 years. The EPA are presumably authorative enough for you and they are using the values from the IPCC AR5. These are GWP(100 yr) = 28 to36 and GWP(20 yr) = 84 to 87.

    I would add that while landfill does produce methane (being anaerobic) and garden composting CO2 (being aerobic), in my neck of the woods (UK) methane from landfill is being put to good use generating electricity although it can also be carted away and pre-processed before landfilling, (plans for such pre-processing being in hand for the tip over the hill from me). Thus collection of garden waste for landfill can be improving on the emissions from garden composting that waste as the renewable energy produced reduces the generation and thus emissions from fossil-fuelled power-stations.

  46. MA Roger @45 Thank you. That's exactly what I wanted. I am in UK too and I did wonder about the methane harvesting possibility but my neck of the woods is Powys in Wales which has a pathetic county council and I doubted that their heads are in the right century. I could be maligning them. I'll check and get back to  you. 

  47. Just read the USA today opinion article entitled, "Let them eat steak: Hold the shame, red meat is not bad for you or climate change."

    My concern was not over whether eating meat was unhealthy or not.  It was the claim that it didn't effect AGW because livestock only account for a 2,6% increase in CHG's.  I checked a 2017 study in PNAS which verified the 2.6% reduction in greenhouse gases due to other factors ivolved in increasing the amount of plant production.

    The thing for me is; are we bound to keep producing plant based food under the methods were producing it today?  Do we have to keep producing plant based food with the same CHG intensity that were presently producing it at?  My family grows 16 acres of organically grown vegetables in field and high tunnels but I'm skeptical that it can be the solution for feeding the world at this point in time.  

    The study also concludes, "the removal of animals resulted in diets that are nonviable in the long or short term to support the nutritional needs of the US population without nutrient supplementation."  My wife and son eat absolutley no meat and I'm what I like to term a "social caravore."  If your serving meat I'll partake but that's the extent of my fleash eating activity.  I'm 72 and my wife is 69 and my son is 38.  Last year when I told my doctor that unlike my friends and I've never had a stress test or an EKG.  She ordered up an EKG.  The tech came in and did the test.  About 15 minutes he popped her head in the door and said, "Your an athlete, arn't you?" to which I replied, I'm a farmer.  I'm not sure why our diets would need suplamention.  I'm concerned about what I'm reading.

  48. Estoma@47,

    As a pursuer of improved awareness and understanding, and the application of that constant learning to help develop lasting improvements for all of humanity far far into the future (this planet should be habitable for about 1 billion years), my understanding is that what matters regarding food is:

    • the way that food is produced
    • the amount of a type of food that is consumed
    • the amount of consumption of non-nutritious stuff
    • the ability of everyone to get adequate nutrition (and healthy water and healthy air)

    The Sustainable Development Goals provide a robustly developed comprehensive basis for evaluating the acceptability of: what has developed, the required types of new developments, and corrections that are required.

    And pursuing improved awareness and understanding makes it clear that competition for impressions of superiority measured by popularity and profit have driven the development, and resistance to correction of, the following harmful unsustainable food production and consumption results:

    • Desires for unhealthy harmful unsustainable Diets. Many people in supposedly more advanced nations develop a liking for eating in ways that produce many understandably harmful results.
    • Desires to over-consume, particularly the over-consumption of meat. The body can only process the protein from about 4 oz of meat in a meal. And a healthy diet does not require that 4 oz helping of meat in every meal.
    • The preponderance of over-consumption of non-nutritious stuff.
    • The starvation and malnutrition of portions of the population which is a result of competitions for popularity and profit, including the way people are driven to not be as aware and understanding as they should and could be.

    A major driver of harmful unsustainable developments is successful disinformation and misinformation marketing (Misleading storytelling). That success is due to people developing an 'interest in trying to Win in harmful ultimately unsustainable ways', combined with developing an easily impressed population that resists improving understanding when that awareness and understanding would require changing developed popular and profitable activity and related perceptions of prosperity or opportunity for personal benefit.

    The supposedly more advanced nations have not succeeded at developing populations that pursue improved awareness and understanding. What they have developed is populations easily tempted to be passionately triggered by misleading marketing developed and delivered by pursuers of harmful and unsustainable popularity or profit.

    And Social Media and News Media pursuing popularity and profit can be seen to be publishing a lot of misleading stories that do not help improve the awareness and understanding of what is really going on regarding food.

    The need to correct many things regarding food production and consumption does not mean 'eliminating those things'. However, the fossil fuel burning related to food does indeed need to be ended, not just be reduced.

    With that understanding in mind your concerns are warranted. Reread the article. It will likely become obvious how much of it is sensationalist extremist correction resistant storytelling trying to defend the 'harmful unsustainable creations developed by competition for impressions of superiority measured by popularity and profit' rather than 'helpfulness to developing a sustainable improving future for all of humanity'.

    Many popular and profitable developments of competition for status do indeed need to be corrected to develop a sustainable improving future for all of humanity. Reducing climate change impacts is a major, but not exclusive, part of the required corrections. Human activities that create accumulating negative impacts, like the use of fossil fuels need to be ended. Other changes of human activity that would reduce GHG levels in the atmosphere are also helpful, but do not need to be taken to the extreme correction (the elimination of them) that is required regarding fossil fuel use.

  49. One Planet Only Forever, thank you for your interesting reply.  There hasn't ever been a time when humans haven't advertised to the detrament of society.  I fear that by the time we come to the realization that it might be to little to late.

  50. Estoma,

    I hope that the development of the Sustainable Development Goals improve awareness and understanding of how fatally flawed the developed ways of living are, including but not limited to the problem of methane resulting from human activities.

    There are many examples of undeniably 'unsustainable and harmful developments'. And in each major case there is evidence of damaging resistance to correction.

    The most glaring example of harmful developments and resistance to correction is fossil fuel use. Climate science has unwittingly produced the powerful proof of how fatally flawed the developed socioeconomic-political systems are.

    Hopefully the Climate Science case will be a Tipping-point regarding the awareness and understanding of the need for Governing/Limiting what is allowed to happen to ensure that the results will be sustainable improvements for humanity. Ethical governing/limiting to achieve and improve the Sustainable Development Goals, including limits on merthane production, is undeniably required when people pursue Personal Benefit or Status relative to Others, especially in Competitions for Popularity and Profit.

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