A methane emergency?

There was an article a couple of days ago about why the climate emergency is now the methane emergency. I appreciate that the general argument is about limiting future warming, but some of what is suggested is essentially wrong.

For example, it says we’re facing tipping points which could trigger runaway warming, which is simply wrong. A true runaway is essentially impossible in our current climate state. The albedo is too high and the sun is too faint. We could trigger some feedbacks that would amplify the warming, and these are expected to become more significant the more we warm. However, if we start to reduce emissions soon and get to (net) zero by around mid-century, then – although these may still be important – they may not be all that significant. I wrote a post a while ago that tried to explain the difference between feedbacks, runaway, and tipping points.

The article then goes on to say

Even rapidly accelerating the end of fossil fuel burning will not slow warming in a timeframe relevant to this threat……….

To slow warming we must keep our focus on cutting CO2 but now also focus intensely on the shorter lived, far more potent gases such as methane.

The science explains this. Whereas CO2 drives warming slowly over a century, methane drives warming quickly – in around a decade.

I agree that we should keep our focus on CO2 and also focus on the shorter-lived species, such as methane. However, the claim that CO2 drives warming slowly over a century is wrong. Peak warming from a pulse of CO2 actually occurs after about a decade. Hence, reductions in CO2 emissions will occur on a similar timescale. Hence, we should be careful of thinking that dealing with short-term warming requires a more intense focus on methane, rather than on CO2.

The article then goes on to suggest that the warming potential of methane over a period of 10 years is 90-115 times that of CO2. What this is referring to is the global warming potential (GWP) and it is indeed the case that this is much greater for methane than for CO2. However, it doesn’t quite mean what the article implies.

How much warming we get from methane emissions depends on how they’ve been changing. If emissions are going up, then this will result in warming. However, if they’re constant there should be little additional warming. If they’re going down, then some past warming will actually be reversed. So, methane does indeed have a much higher GWP than CO2 over a timescale of decades, but this doesn’t necessarily mean that methane emissions will drive much more warming than CO2 emissions. If you want to understand why this is, I tried to explain it in this post, and this Carbon Brief article by Michelle Cain is also very good.

Essentially, as long as we are emitting CO2 there will be CO2-driven warming, which will only stop (but not reverse) when CO2 emissions go to zero. Warming due to methane, on the other hand, will mostly stop if we get methane emissions to stabilise, and will reverse if we get methane emissions to go down. Given the differences between methane-driven, and CO2-driven warming, how much we will eventually warm depends mostly on how much CO2 we end up emitting.

Of course, this doesn’t mean that we shouldn’t worry about methane emissions. According to the latest IPCC report, methane accounts for a reasonable fraction of the warming we’ve experienced and, since methane emissions are still increasing, will contribute substantially to future warming. If we want to meet the Paris targets, then we will need to deal with both methane and CO2 emissions, especially if we don’t want any overshoot.

However, we do need to be careful of thinking that limiting short-term warming means focussing on methane. As pointed out in this Realclimate post, the long atmospheric lifetime of CO2 means that any delays to CO2 emission reductions are likely to commit future generations to warming that is difficult to reverse and could have been avoided. Methane’s short atmospheric lifetime means that delays to methane emission reductions don’t carry the same risk.

This doesn’t mean, though, that near-term methane emission reductions aren’t important (they are if we want to meet current targets without temperature overshoots). The main point is to be careful of thinking that focussing on methane now can buy us time (it doesn’t) or that it’s now essentially become a methane emergency (it hasn’t).


Why the Climate Emergency is now a Methane Emergency – article in resilience.
Feedbacks, runaways, and tipping points – post I wrote trying to explain these different issues.
Losing time, not buying time – Realclimate post explaining why focussing on methane emission reductions doesn’t really buy us time.
Methane – other posts I’ve written trying to explain the differences between methane and CO2.
A new way to assess ‘global warming potential’ of short-lived pollutants – nice Carbon Brief article by Michelle Cain presenting a new way to quantify the GWP of short-lived pollutants.

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46 Responses to A methane emergency?

  1. “A true runaway is essentially impossible in our current climate state.”

    Because climate scientists are not physical chemists, material scientists, or condensed matter physicists for that matter, they somehow seem incapable of deriving that the well-known Arrhenius activation energy will not lead to a runaway positive feedback. Yes, it’s a positive feedback in the case of GHG catalysis (CO2 => H2O), but it’s self-limiting when one works out the rate equations. I have yet to find this derivation in any climate science text. Josh Halpern should pipe in on this.

  2. Why do you think they can’t do it? Most are well aware that it’s not possible in our current climate state.

  3. All true, I think. The argument over focus seems like a distraction to me. I think of hurricanes these days and the following analogy comes to mind: Let’s say we live on the Louisiana coast where Ida made landfall. One person says, the winds are the big problem. They “know” this because their neighborhood is on high ground, sustained little flooding problems, but the neighborhood had roofs ripped off buildings. Another person says, no, the wind is not the big problem, the big problem is the amount of rain we received. They “know” this because their neighborhood was in a low-lying area that sustained no wind damage, but is now flooded waist deep in storm water. A third person says, no, it’s the not the wind or the rain, it’s the tsunami of the storm surge that is the big problem. They “know” this because they live right at the coast edge and they saw huge waves rise up out of the Gulf storm and wash away the buildings on their ocean front street.

    A fourth person then jumps in and says, well a tsunami is quite different from storm surge. To get a tsunami, you start with an earthquake and there has been no earthquake, so you shouldn’t say tsunami, the right term is storm surge.

    Me, the fifth person, says, yeah, this is awful. The big problem is the hurricane that brought us torrential rainfall, disastrous wind and a tsunami-like storm surge. This is a really terrible hurricane.

    Global warming is a big problem brought on by human activity that caused disastrous levels of greenhouse gases to accumulate in the atmosphere. I think that we don’t have time to waste arguing about the specific impacts of each greenhouse gas or the misuse of certain descriptive terms. I think we need to recognize that we are now in a global emergency where we need to stop the emissions of all the greenhouse gases and start working on reduction of the accumulation of gases and heat that already exist in the atmosphere and oceans to move our global climate back to a less dangerous state. We should do this as quickly as we possibly can. We need to do it faster than we possibly can because there are high impact, low probability events that we really don’t want to experience.



  4. My request is find a published analytic derivation whereby an activation energy (Maxwell-Boltzmann statistics, Clausius-Clapeyron, Arrhenius https://en.wikipedia.org/wiki/Arrhenius_equation#Theoretical_interpretation_of_the_equation) catalyzes a positive feedback but that positive feedback is self-limiting and does not cause thermal runaway. This is a concern for science communication because in many SciTech disciplines, positive feedback typically does lead to runaway (especially in electronics) and it is those people that are often confused by the topic.

    So for methane emissions, say from frozen methane clathrates, the fear is that since clathrate outgassing is thermally activated, it will generate a positive feedback and possibly thermal runaway. But knowing the activation energy of clathrate sublimation, one can potentially show the limit of further warming to a specific set T point.

    I have never found this general derivation anywhere in the literature. Suggested search terms: “t point” clausius clapeyron “catalyzed” “outgassing”

  5. Eabani says:

    I also differ from Paul Gilding’s conclusions, but the article was worth reading and I like the interdisciplinary perspective. The RealClimate link is more authoritative.

    To start with the word ‘runaway’, sure most physicists don’t think it’s possible for the oceans to evaporate away until another 500 million years have elapsed and the sun is that might brighter.. However, ‘runaway’ also has a colloquial meaning that James Hansen has also used more recently akin to the domino effect of ‘Trajectories of the Earth System in the Anthropocene’. My impression from AR6 WG1 is that most things are proportionate up to 2 °C with some threshold effects like Greenland and AMOC shutdown that can’t be ruled out. That’s of course is WG1, and many ecological and social effects are non-linear in even less predictable ways. It would be good to avoid the ambiguity of ‘runaway’, but let’s go with the intended meaning.

    Doesn’t Paul Gilding’s group share something with David King’s Climate Crisis Advisory Group recently looking into ‘refreezing’ the Arctic using Solar Radiation Management? CCAG explores stopping carbon-cycle feedbacks, the ‘runaway’ some fear, because it’s hard to get the carbon back in the permafrost. Of the carbon-cycle feedbacks Amazon dieback actually seems the most prominent in AR6 WG1 (a counter-example to ‘wet gets wetter’).

    Then there’s trying to compare CO₂ and methane using the same metric, as is done worldwide under the GHG Protocol. I would argue with Ken’s response here as I understand it. I propose CO₂ is ‘longer-term’ than methane, but not because of any lag in warming peak. It’s simply because it is incremental. Emissions affect forcing and warming more or less immediately, but not very much in any given year. Whereas methane is all about rate of release over a decade, so if you wanted a limited cooling of a fraction of a degree within a few years, there is a case to stop methane – if it could be done. AR6 WG1: ‘New emission metric approaches can be used to generate equivalent cumulative emissions of CO₂ for short-lived greenhouse gases based on their rate of emissions. {7.6.2}’ and there’s a whole chapter in Short-Lived Climate Pollutants (or Forcers). Figure SPM.2 seems to show methane towering over the other SLCPs, responsible for 0.5 °C warming by itself. That’s partly offset by aerosol cooling, but more than half the contribution of carbon dioxide. WG1 suggests to me this is about half from current fossil fuel extraction (including oil flaring, gas fugitive emissions and coal mines) and half from current agriculture. I’m confused about how carbon-cycle-feedbacks of methane appear in this diagram: such feedbacks include not only melting permafrost but soil and in particular tropical wetlands, a source that seems to be a response to longer-term warming.

    Before and after WG1, some have also been worrying – excessively in my (uninformed) opinion – about short-term aerosol unmasking. This is a fraction of a degree and even shorter-lived than methane. So trying to offset the one against the other makes some possible sense (although the IPCC assumption of scenarios in table SPM.2 is that CH4 warming is proportional to CO2 warming). I’d question Mr Gilding on how to turn this into policy. Fertilisers are responsible for more than twice the AFOLU (agriculture, forestry and land use) emissions as ruminants, and rice paddies contribute 6% (Berners-Lee, TINPB). Stop deforestation urgently, but agriculture is probably not easy to transform without disruption and hardship (I say this as a vegan). The lifetime of a cow is not much shorter than a power station, and more valuable in some places. There are links to artificial vertical farms and proteins derived from bacteria, which even if they could scale up in the timescale implied, displace traditional cultures and livelihoods and do not strike me as either sustainable or tasty.

    Instead let’s look at the other half of methane sources identified by IPCC. The UK O&G industry is promising to halve its Scope 1 operational emissions within 10 years. I hope Mr Gilding is right that methane from fossil gas will be ‘largely gone’ in 10 years, but they’ve convinced governments that they’re here for at least 20 years after that, and despite what he says, to invest in this ‘efficiency’. The efficiency actually makes fossil fuels more competitive than renewables so is planned by O&G to increase total extraction and so maximise Scope 3 (category 11) CO₂ emissions. I hope the UK’s ‘North Sea Transition Deal’ does fail despite the enormous financial backing, because it’s transition to higher emissions. Methane is also one of the principal objections to the proposed coal mine in northern England. The article also doesn’t recognise that landfill gas collection has been an great success in the UK, and no reason that cannot be replicated at least in developed countries that should be grown-up enough to clean up their own waste. So there are two ways of focusing on methane: one, which I prefer, and the article seemingly assumes will happen, of burning fossil carbon coming to an end sooner rather than later; second, the whole idea of offsetting and reducing methane being used as cover for continued emissions of the long-lived greenhouse gas, along with tree planting and other reversible GGR. IPCC also illustrates with a some synergies (particularly long-term) between air quality now and climate mitigation (box TS.7 etc). The simple solution, focused on by effective NGOs like 350 and Oil Change International, cuts the CO₂ and the methane at the same time, leaving the space to be filled by existing sustainable and renewable technology.

    It’s not just that focussing on methane cannot buy us time. We shouldn’t focus on ‘buying time’. I’m afraid that’s just buying time for fossil fuels that are capable of aggravating global heating for another century. Avoiding overshoot might conceivably also avoid one or two species going extinct, but on a timescale much shorter than human history AFOLU seems likely to balance out and the main concern around land-use from a social perspective is food security and from an environmental one is habitat destruction; IPCC shows agricultural methane is a tiny contributor after 100 years (fig TS.20). It’s the amount of carbon that’s dug up and injected into atmosphere (causing global warming) and ocean (causing acidification) that in my opinion it’s important to prioritise.

  6. Eabani,

    Whereas methane is all about rate of release over a decade, so if you wanted a limited cooling of a fraction of a degree within a few years, there is a case to stop methane – if it could be done.

    Yes, there is some truth to this. If we were able to quickly stop methane emissions, we could reverse a significant fraction of a degree of warming on the timescale of a decade or so. Realistically, we probably can’t do this – agriculture makes up a big chunk of methane emissions and we can’t – I think – stop this in the near term. However, you’ve reminded me that about 35% of methane emissions are associated with fossil fuel extraction. So, if we wanted to limit methane emissions in the near term, it would seem that focussing on fossil fuel use could have a reasonable impact.

  7. Ben McMillan says:

    I think technically it would be possible to dramatically and fairly quickly reduce methane emissions in agriculture (by demand side and production side measures). But there are reasonable arguments against doing this.

    On the other hand, agriculture is a big contributor to long lived greenhouse gas, and could help capture carbon: I think it is a mistake to just put it in the too-hard basket. The land sector needs to be part of the solution.

  8. Ben,
    Yes, fair point about agriculture’s contribution to the emission of long-lived GHGs.

  9. Eabani says:

    Ben, I wasn’t really thinking about CO₂ and agriculture. Did you read Ray Pierrehumbert’s essay on RealClimate? It’s a very informed argument against GWP100 and for not conflating the two forcings, and I would say for not conflating the fossil fuel problem and agriculture. There may be ways to use land for carbon sequestration, most permanently biochar. Project Drawdown explains silvopasture and agroforestry, but many claims about soil carbon seem speculative to me. https://www.soilassociation.org/media/17472/to-plough-or-not-to-plough-policy-briefing.pdf

    Reducing agricultural methane on supply side may be possible, by not flooding paddy fields and by changing diet of ruminants. Were there other supply-side measures you meant? I can’t see paddy field and diet changes, if they were adopted globally, taking us back to pre-industrial rates of release and atmospheric forcings. I happened to tune in to Farming Today one morning to hear Myles Allen assure beef and dairy farmers that so long as they kept the same head of cattle they aren’t contributing to global warming. (As ATTP says ‘Warming due to methane, on the other hand, will mostly stop if we get methane emissions to stabilise’.) Methane and CO₂ have to be two factors among many others with land use. What did you think of the proposals on the ‘methane emergency’ article? Deforestation as part of the ‘frontier cycle’ for cattle and timber is a bigger contributor to GWP100 than enteric emissions. My justification for going vegan a few years ago was to do with habitat destruction rather than climate.

    Sorry my earlier comment was so badly written, but ATTP got the gist of it.

    ATTP: ‘how much we will eventually warm depends mostly on how much CO2 we end up emitting’. There were several stories concentrating on methane in the first couple of days after AR6 WG1 publication, but I can’t find reasons for that in the report or press release.
    IPCC: ‘Over 10- to 20-year time scales, the influence of SLCFs is at least as large as that of CO2, with sectors producing the largest warming being fossil fuel production and distribution, agriculture, and waste management. Because the effect of the SLCFs decays rapidly over the first few decades after emission, the net long-term temperature effect from a single year’s worth of current emissions is predominantly determined by CO2 .’ From this year’s emissions, after 100 years, black carbon and nitrous oxide are more important forcers than methane, and CO₂ is ten times more important.

    It’s not really a physics point, I’m also guessing that were it such a methane emergency that we were mostly concerned with the next two decades, we’d still be back on the long-term trend after that and emergency implies long-term stresses and loss of capacity to mitigate. And given all the other problems with coal, oil and gas…

  10. Eabani,
    Yes, I don’t fully understand why we’re seeing all these articles about methane being key when how much we eventually warm will depend mostly on CO2.

    As far as I can tell (and this may relate to Ben’s point) if we were to focus on CO2 emissions, both in the fossil fuel sector and in agriculture, you’d still probably end up reducing methane emissions. If our immediate goal is to limit how much we warm in future, this would seem like a reasonable strategy. Once we’ve started to see CO2 emission reductions, we could then think more about reversing some methane-driven warming by trying to then increase methane emission reductions.

  11. For reductions of CO2-emissions goes the same Law of diminishing returns as for any other achievement. The first steps, to start with stabeising emissions on the present high levels, will give the most returns but any further step will cost way more and brings very little in terms of a reduction of CO2-levels. And this is possible. Antropogene CO2 wont stay in the atmosphere for ever. Eventually it will fall out of it.

  12. Raymond,
    Technically, to get atmospheric CO2 levels to start reducing (without anthropogenic negative emissions) requires getting our emissions to zero. Until we do so, we’ll keep warming. There will come a point where the cost of not getting to zero emissions will exceed the cost of doing so.

    Antropogene CO2 wont stay in the atmosphere for ever. Eventually it will fall out of it.

    It will eventually be taken up by the natural sinks, but the timescale is ~100 kyr.

  13. Chubbs says:

    Agree that the article is off base in some areas. Good luck getting people to stop eating meat rapidly.

    Noodling some numbers from AR6 + NOAA:
    Methane forcing per ppb = 0.00038 W/m2
    CO2 forcing per ppb = 0.000013
    Methane lifetime = 11.8 years
    Methane 1750 = 791 ppb
    Methane current = 1891 (NOAA)

    Halting methane emissions would drop methane by around 100 ppb the first year (1200 ppb/11.8), which would reduce forcing by 0.04 W/M2, which is the forcing produced by roughly 2.8 ppm of CO2. So an instantaneous halt to methane is roughly equivalent to one year of CO2 emissions, i.e. in the same league as halting CO2 emissions. The main difference is the methane benefit would decay with a half-life of 11.8 years, while the CO2 benefit would persist.

  14. Chubbs says:

    Mistake above. Half-life is only 0.7 * lifetime. So the benefit of halting methane emissions would decay even faster – with a half-life of 8.2 years.

  15. Although some effort needs to be made understanding the rationale behind and strengths/weaknesses¹ of “Global Temperature Change Potential” (GTP) metric, I’ve always thought Figure 8.33⬆️ from IPCC AR5 WG1 Chapter 8 is a real “let’s separate the men from the boys” presentation of the ultimate warming impact of our current emission loads.

    If you are going to argue, say, that “Now it’s a methane emergency!”, you’d better be able to fluently explain exactly what this graphic is saying², and how you are making your case in light of it.

    ¹ yes, you need to look at continuous flow forcing metrics as well, but this just highlights why solving the global warming problem ultimately always comes down to effectively solving the CO₂ problem.

    ²caption “Figure 8.33 | Temperature response by component for total anthropogenic emissions for a 1-year pulse. Emission data for 2008 are taken from the EDGAR database and for BC and OC for 2005 from Shindell et al. (2012a). There are large uncertainties related to the AGTP values and consequentially also to the calculated temperature responses”, but GTP and figure more fully described in Chapter 8⬇️

    Click to access WG1AR5_Chapter08_FINAL.pdf

  16. Ben McMillan says:

    As well as understanding the lifetime of CH4 vs CO2, it is also important to understand the absolute forcing due to emissions:

    i.e. CH4 is not a minor contribution.

    The thing that makes CH4 such a useful lever (in a scenario where we also bring CO2 quickly under control) is that it is plausible that we might be able to bring emissions to much lower levels, and quite quickly reduce the forcing. At the moment CH4 emissions are instead rising.

  17. Eventual_Horizon says:

    Methane is such a fascinating actor in the AGW space. Much of its role in future warming seems to hinge on the stability of its atmospheric lifetime which is currently pegged at around a decade (9.25 years according to AR5).

    Hydroxyl, the primary sink for CH4, has been on an upward trend the last couple decades. According to AR6:

    >> there is medium confidence that this trend is mainly driven by increases in global anthropogenic nitrogen oxide (NOx) emissions and decreases in anthropogenic CO emissions.

    What I’ve not been able to find expert opinion on is the likelihood of sink degrade. Is there an equilibrium point between OH and CH4 after which additional CH4 has a significantly longer lifetime? An increase of even a couple years could significantly throw off climate projections. NOx, which boosts OH presence, will likely decline as fossil fuels are phased out. I can’t find any good numbers on CO sources and how they might change into the future.

    While calls for a “methane emergency” might be overdone the unpredictable nature of CH4 (relative to the plodding line of CO2) is cause for concern. Consider that last year we had the largest ever YoY increase in CH4 despite the COVID shutdown.

  18. Ben McMillan says:

    Eabani: those technical measures for reducing methane sound promising. No doubt they won’t by themselves reduce methane back to preindustrial levels, but that seems like a rather extreme criterion: we just need to do the things that are helpful.

    But in order to make progress in learning how to reduce methane emissions, you have to incentivize farmers to learn how to reduce emissions, and then build out the infrastructure to do so, using a carbon price or similar. This is not going to be a rapid process.

    Similarly, some people are eating less meat+dairy, or eating different meat, for environmental reasons, but that isn’t going to happen fast (i.e. generations). Encouraging that process along somehow seems desirable.

    So I think the idea that we can cut methane ‘once we have dealt with CO2’ with optimal timing is somewhat misguided. You can do it with a curve on a piece of paper but the real world things change too slowly and you should have started 20 years ago.

  19. Willard says:

    > At the moment CH4 emissions are instead rising.

    I’m not sure how we could reduce them if we keep adding cattle:

    The world now produces more than three times the quantity of meat as it did fifty years ago. In 2018, production was around 340 million tonnes.


  20. Pingback: Implications for mitigating methane emissions in agriculture | …and Then There's Physics

  21. Ben,

    So I think the idea that we can cut methane ‘once we have dealt with CO2’ with optimal timing is somewhat misguided. You can do it with a curve on a piece of paper but the real world things change too slowly and you should have started 20 years ago.

    Indeed, and this is certainly not what I’m suggesting. Mostly I’m just pointing out that we can’t use reductions in methane emissions as some alternative to cutting CO2 emissions, or as some way of buying time. However, as I understand it, if we were to successful cut CO2 emissions, both in terms of reducing fossil fuel use and reducing (or even reversing) some LULC emissions, then that would also have an impact on methane emissions.

  22. Ben McMillan says:

    ATTP: Yes, thanks, I agree that the “buying time” rhetoric in particular is incorrect. Possibly methane emissions would fall anyway in a world where we only regulated CO2.

    But rather than hoping it occurs as a secondary effect of CO2 reductions (I guess neither you nor Ray P may actually be advocating this), I think it would be much more robust and direct to just regulate methane emissions. This is the standard way to deal with pollutants. If the concern is that CH4 regulation might indirectly impact on CO2 reductions, ideally you would design the regulations to avoid that, instead of abandoning regulation of CH4 entirely.

    Direct regulation has the advantage of, e.g., avoiding situations where we reach “net” zero CO2 emissions by using fossil gas with carbon capture, but there are big unregulated fugitive CH4 emissions. In general fugitive CH4 emissions now are causing real damage over the next 20 years or so and it is worth giving gas producers some incentive to fix their leaks (beyond the very minimal incentive of getting most of their gas to the buyer).

    Some of the “methane emergency” stuff is nonsense, but methane is still a real problem.

  23. Ben,

    I think it would be much more robust and direct to just regulate methane emissions. This is the standard way to deal with pollutants. If the concern is that CH4 regulation might indirectly impact on CO2 reductions, ideally you would design the regulations to avoid that, instead of abandoning regulation of CH4 entirely.

    Indeed, I agree. I mostly think that we should treat methane (and other short-lived species) and CO2 (and other long-lived species) separately. I’m not that concerned about regulating methane emissions impacting CO2 emission reductions. I agree that we could design regulations to avoid that. I’m mostly concerned that some don’t quite realise that it would be important to do so.

  24. Dave_Geologist says:

    Because climate scientists are not physical chemists, material scientists, or condensed matter physicists


    More contentfully, even Venus runaways have an “out-of-fuel” limit, as I believe we’ve discussed on previous posts. Eventually the planet gets hot enough (around 2000K IIIRC) that the surface radiates directly to space at wavelengths to which the steam atmosphere is transparent. Snowball Earths have a limit when the entire planet is white and you can’t add more albedo. Etc.

    As I put it at the time, it’s a runaway until the rules change. Then it’s not.

    Your difference is a difference that makes no difference.

  25. Dave_Geologist says:

    There should be easy wins (although as I suspect a lot of those wins are in the USA, Canada, China and USSR, where for various political, economic and governance reasons they’re not so easy).

    In the oil and gas sector there tend to be a few “super-emitters” when it comes to fugitive emissions (leaks from valves, pumps, pipelines etc.). The distinction often being not that they are catastrophic leaks (catastrophes get fixed, in hours, days or at worst, months). But that they’re the ones emitting all year round. The rest fix the leak, either following detection or during routine maintenance.

    Intermittency of Large Methane Emitters in the Permian Basin

    There should be an incentive not to leak stuff that you can sell. But flares when you’re tied into an oil pipeline but have no gas pipeline, and perhaps a lesser incentive for third party transporters (they don’t own the gas, but do they incur a wastage charge from the owners when less comes out than went in?) need regulation, carbon taxes etc. to encourage good behaviour. Some is unavoidable, like flaring when you’re flowing back frac or drilling fluid and all you have on hand is a road tanker. But that’s transient and will soon be gone. It’s the next 30 years you should worry about.

  26. Dave_Geologist,
    The Earth has already gone through a positive feedback path to arrive at its current temperature set-point. Venus is different because the atmosphere is mainly CO2, whereas Earth uses CO2 as a catalyst to promote the H2O concentration in a feedback cycle. The argument is that the Earth has already gone through a very limited “thermal runaway” cycle to reach the set-point it is at now. Any further increase in CO2 will force the Earth to another set-point, as an incremental “runaway”.

    Cited a derivation on this blog last year :

    As I said earlier, I was asking whether this derivation exists anywhere else besides my textbook. This shouldn’t be hard to find, but it is because most descriptions are of the hand-wavy variety and AFAICT no one has done the straightforward T-point calculation. One would think this is important in terms of science communication, especially for those that don’t understand the distinction between runaway and positive feedback.

  27. Joshua says:

    Off topic, but considering !!!CAGW!!!

    I thought this is kind of interesting:

  28. Dave_Geologist says:

    Paul, to be more precise the distinction I was making was between “running out of fuel” and ending what looked superficially like a runaway, and the methane release or whatever being a strong enough positive feedback to initiate a runaway, where each increment of methane (or albedo, or whatever) shifts the dial enough to release a larger increment of methane or whatever. You may reach a new set point if you want to call it that, say a surface temperature radiating in the near-infrared (on reflection a rule change rather than running out of fuel, because the GHGs are still there they’re just not GHGs any more), or you may reach a point where the planet can’t get any whiter (running out of fuel).

    So, for example, the Great Dying appears to require the combustion of large amounts of coal as well as a Large Igneous Province (it would have been bad anyway as it’s the largest Phanerozoic LIP). But no amount of CO2 emission from burning coal will make more lava intrude or erupt, so the product of the burning coal can’t be a feedback which causes more coal to burn. Nevertheless it stopped when the coal ran out. The same goes for the PETM if the dose of methane came from maturation of oil source rocks into the gas window by the North Atlantic LIP. But if the dose of methane came from destabilised permafrost or hydrates it might be. Or it too might just be a matter of running out of fuel (the Antarctic permafrost was probably that because in the most popular model, it all went whoosh when the Antarctic Plateau rose above freezing all at the same time – the only thing making it not instantaneous was latent heat and it would all have gone even if temperature cease to rise due but just held still).

    When you are unfamiliar with a field, and are surprised that they aren’t doing things your way because they’ve got their own ways to do it – since at least the 1980s – usually involving numerical models not hand-waving because spherical cows give the same answer wherever the continents and mountains are and models, like real worlds, don’t, you might stop to wonder whether they know something you don’t. Rather than reverting to argument from non-authority. The “they’re all just dumb geographers” card.

  29. Joshua,
    I also saw that, but it’s only really interesting in the context of a debate that has been blown out of proportion. There’s a huge overlap between people who think we should study worst case scenarios and who also think that we’re moving along a pathway that is making them increasingly unlikely. If people were engaging in good faith, then the whole RCP8.5 debate could have involved some people saying something like “it’s become increasingly unlikely and we should stop calling it BAU” and another group responding with “good point”.

  30. Dave_Geologist,
    OK, then present the mathematical derivation to show this guy why the positive feedback stops where it does (this is from a comment on the Talkshop blog from today).

    Dan says:
    September 1, 2021 at 7:27 pm
    “This has been self-evident forever, at least in terms of water vapor which is, I believe, a much more potent greenhouse gas than CO₂. Heat causes the oceans to emit water vapor, which should, according to mainstream GHG theory, cause more heating, which should cause more evaporation, more heating, ad infinitum. A positive-feedback loop hockey stick that should be ending in disaster. Only it doesn’t.

    I’m sure the “world’s leading climate scientists” will just look sneeringly down their noses and shake their heads at how the proles like me just don’t get it.”

    I know why it stops, and actually why it never gets there from H2O alone (as it’s driven to its lower set-point instead of the upper set-point). Ever think that they might be convinced with a rigorous derivation?

  31. Bob Loblaw says:

    Ever think that they might be convinced with a rigorous derivation?

    Uh…. No.

  32. Joshua says:

    Anders –


  33. “Uh…. No.”

    In electronics, an unconstrained positive feedback invariably leads to a runaway that will eventually clamp to the voltage rails or in a smoked circuit. So the trained electrical engineer is puzzled by the fact that everyone in climate science is talking about positive feedback yet the outcome has yet to show the characteristics of a runaway, in particular an accelerating rise in the output. So they think the model is faulty — after all, amplifiers use negative feedback to maintain a gain.

    The ones that want to learn will be swayed. Those with a political agenda won’t.

  34. Dave_Geologist says:

    Paul, toy models divorced from physical reality rarely convince beyond their domain. Especially when presented with a “why don’t you dumbasses get it” attitude. Perhaps a change of attitude would get you the attention-span needed to convince the professionals who’ve spent decades in the field. Or perhaps you need to learn about the subject first (I’ve lost count of how often you’ve said geophysicists don’t do x, y or z, only for me to point out decades-old literature doing exactly that). IIRC one was the top hit on Google, not even Google Scholar. Dan could do with some learning too, Starting with Planck and Stefan-Boltzmann. After all, then there’s physics.

    See previous discussions about closed-form solutions. See also the title of this blog.

    If it appears at all, this will be my last word on the topic.

  35. Ben McMillan says:

    ATTP: OK, I understand that you would prefer some kind of independence to regulation on CH4 and CO2.

    One issue is that there is limited wiggle room because the world has pretty much already agreed to use GWP100 as a common metric for the different species for the purposes of regulation (I think this is somehow baked in the Paris Agreement).

    This wasn’t entirely arbitrary, either; I think this was a result of careful consideration of the relative importance of short vs long-lived forcing agents. i.e. GWP100 is a compromise to give the “right” weighting and not overstate the importance of short-lived products.

    Obviously GWP100 is a terrible way to generate forcing time-series, though (as you have pointed out), but I think that it wasn’t really intended to do this.

  36. Ben,
    To be honest, I’m not sure what I’d actually prefer. Probably to find ways to limit our emissions of all GHGs. I realise that these metrics are just simple ways to treat different species in a similar way, even if they aren’t perfect. Maybe it is fine to just accept this and realise that even though the metrics that are being used aren’t perfect, they will still be mostly okay. I guess I just share Ray Pierrehumbert’s concern that some will think that methane is the most important for the near-term and that CO2 is more important for the long term and that they will (incorrectly, in my view) use this to argue for an increased focus on methane now, at the expense of reductions to CO2 emissions. Ultimately committing future generations to warming that could have been avoided. However, I also realise that if we don’t stop increasing methane emissions soon, then that will have a big impact on near-term warming. It’s complicated 🙂

  37. Bob Loblaw says:

    Paul: you quoted someone that was saying “Heat causes the oceans to emit water vapor, which should, according to mainstream GHG theory, cause more heating, which should cause more evaporation, more heating, ad infinitum.”

    Anyone that argues that does not belong to the group of people “that want to learn”.

  38. Dave_Geologist said:

    “Paul, toy models divorced from physical reality rarely convince beyond their domain.”

    Well, I published that derivation in a monograph titled Mathematical Geoenergy (Wiley/AGU, 2019) starting on page 269. So if you want to criticize it as a toy, you or anyone else can do so on a forum such as PubPeer.

    Yesterday, a MET prof rhetorically tweeted “Time to start having those layperson-friendly discussions about the Clausius-Clapeyron equation”.

    Scroll down to veteran atmospheric scientist Tim Dunkerton’s “why don’t you dumbasses get it” response “Dynamical systems aren’t constrained by energy in any but the weakest and most meaningless way. It’s all about vorticity substance. Axiomatic.”

    Fun stuff.

  39. Just to clarifying a few things. The reason water vapour doesn’t lead to a runaway in the standard greenhouse effect is because the Planck response always wins. However, it we were to get into a very moist greenhouse state while there was still a reservoir of water on the surface, you can eventually get to the Kombayashi-Ingersoll limit; essentially the outgoing flux decouples from the surface temperature (i.e., increasing the surface temperature does not increase the outgoing flux). If the incoming flux exceeds the outgoing flux, then runaway ensures until the surface temperature gets high enough that the outgoing flux can start increasing again. We essentially can’t undergo the latter in our current state.

    Chris Colose explains this in this Skeptical Science post.

  40. “The reason water vapour doesn’t lead to a runaway in the standard greenhouse effect is because the Planck response always wins.”

    The Planck response T^4 is already subsumed into the logarithmic climate sensitivity (a log will eat a power term and spit it out as a scale factor). The discussion is about how to analytically solve the Clausius-Clapeyron relation for stable set-points well before it reaches the “Komabayashi-Ingersoll” limit. Maybe everybody thinks it is obvious — an exercise left for the readers, as they say.

  41. Bob said:

    Paul: you quoted someone that was saying “Heat causes the oceans to emit water vapor, which should, according to mainstream GHG theory, cause more heating, which should cause more evaporation, more heating, ad infinitum.”

    Anyone that argues that does not belong to the group of people “that want to learn”.

    In the quote, replace “oceans” with “permafrost hydrates” and “water vapor” with “methane” and you may find people willing to learn if that also has a stable set-point. May be more complicated as the methane will decompose to CO2 after some time in the atmosphere, but the heat of sublimation activation energy of a hydrate or clathrate is likely not that much different than the heat of vaporization activation energy of CO2.

  42. Bob Loblaw says:


    I maintain that anyone that thinks that “mainstream GHG theory” predicts that continually adding more and more water vapour will lead to “heating, ad infinitum” has no clue about “mainstream GHG theory” or the factors that affect the atmospheric portion of the hydrological cycle. They are already in deep Dunning-Kruger territory, and a detailed argument of any sort will be rejected.

    To conclude otherwise would require a more charitable interpretation of their wording. I am not that charitable, but I can understand that you feel otherwise.

    Permafrost does not engage in a highly dynamic methane cycle like oceans do with atmospheric water, and methane is not temperature-restricted in the atmosphere. (People living on Titan may argue otherwise, but we’re on Earth.)

  43. Bob,
    I think its the permafrost tipping point fear. Methane hydrates/clathrates don’t have that much of a difference in activation energy than heat of CO2 vaporization. So the positive feedback effect with temperature isn’t that much more of a ticking time bomb. The distinction is in the land vs ocean temperature and what is involved in the process of settling toward an equilibrium. I doubt that there have been as many studies of this as there have been of vapor-phase growth&doping of semiconductors (likely billions of IRAD $$$) which is what all my academic lab research was based on. After all, money is spent on what can make money.

  44. Russell says:

    A significant piece of news has just emerged on agricultural methane .

    Feed additive giant DSM has secured EU permission to vend a methyl coenzyme M reductase inhibitor that cuts ruminant emissions in half:


  45. Ben McMillan says:

    Valio, a Finnish dairy that is partnering with DSM, has also been trying out a bunch of other things to reduce ruminant emissions, like collecting manure to making biogas. Basic stuff like breeding makes a difference.

    They ran a methane hackathon a few years back to come up with ideas…

    Lots of possibilities for positive changes, also on the other issues of e.g. water use, nitrogen pollution, CO2, and habitat destruction.

  46. mandating use of feed additives that would significantly reduce methane emissions seems like low hanging fruit to me. Nothing about working on such a thing requires that we reduce efforts on other ghg emissions. I think personal use issues like reducing fossil fuels in doing landscaping are necessary, but not sufficient.

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