Halting the vast release of methane is critical

A week or so ago there was a New York Times article called Halting the Vast Release of Methane Is Critical for Climate, U.N. Says. As the title suggests, it was reporting on a United Nations Report that (according to the article) is likely to suggest that slashing emissions of methane, the main component of natural gas, is far more vital than previously thought.

However, when discussing carbon dioxide emissions, the article claimed that:

while it remains critical to keep reducing carbon [dioxide] emissions, which make up the bulk of our greenhouse gas emissions, it would take until the end of the century to see the climate effects.

The problem was that this was wrong. As I point out in this post, if you consider pulses of carbon dioxide emissions, then the maximum warming from such a pulse would occur after about a decade. In other words, the warming from carbon dioxide emissions peaks relatively quickly. Consequently, any emissions we avoid will have an impact on a similar timescale. Hence, it’s wrong to claim that it will take till the end of the century to see the climate effects of reductions in carbon dioxide emissions.

What was impressive was that, after I pointed this out on Twitter, the author (Hiroko Tabuchi) responded to say that they were updating the article. They changed it from it would take until the end of the century, to it will take to the second half of the century. I still don’t entirely agree, but I thought it good that they were willing to take on board the criticism and didn’t really feel like quibbling.

I did want to add, though, that I think that what is being presented in the article is potentially what Ray Pierrehumbert was warning against in this Realclimate post. As I’ve pointed out in previous posts, short-lived greenhouse gases like methane behave differently to long-lived greenhouse gases, like carbon dioxide.

The warming impact of methane emissions largely depends on how these emissions have been changing with time. In fact, if we can get methane emissions to decrease, then that would actually reverse some of the methane-driven warming. When it comes to carbon dioxide, though, how much we warm depends essentially on how much we emit in total. So, limiting carbon dioxide-driven warming requires limiting how much we emit in total, and reversing carbon dioxide-driven warming would require artificially removing carbon dioxide from the atmosphere.

There are certainly good reasons for cutting methane emissions now, and it would almost certainly have an impact on a very short timescales. However, we do need to be careful of framing this as some trade-off between reductions in methane emissions and reductions in carbon dioxide emissions. To limit long term warming requires limiting how much carbon dioxide we emit. In the absence of some kind of negative emission technology, any delay in carbon dioxide emission reductions will either commit future greaters to greater warming, or will require much more drastic emission reductions in the future.

So, I do think we should be cautious of suggesting that because reductions in methane emissions can have a large short-term climate impact that we should focus on this now, partly because it’s not the case that this isn’t true for reductions in carbon dioxide emissions, and partly because long-term warming is going to be dominated by how much carbon dioxide we emit. Of course, if there are easy ways to reduce methane emissions now, then we should do so. There may also be other reasons for reducing methane emissions now and we certainly don’t want it to continue increasing. Let’s just not forget that to limit long-term warming requires limiting how much carbon dioxide we emit.

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43 Responses to Halting the vast release of methane is critical

  1. Tom Fuller says:

    Should we change how we feel about rice? Or at least call for change in paddy cultivation practices?

  2. Tom,
    If you’re referring to that rice cultivation emits methane, then I’m certainly not an expert on that particular process. However, this is one reason why it’s important to understand the relationship between methane emissions and warming. If methane emissions are not increasing then their warming impact is potentially small, and reductions in methane emissions can actually reverse some previous methane-driven warming. So, we don’t necessarily need to aim for net-zero methane emissions. If there are methane emissions associated with food production (which is clearly an important process), then we could look for ways to reduce those emissions, but we don’t need to aim for zero methane emissions (from a climate warming perspective, at least).

  3. Do you observe any evidence that humans can/will limit our carbon dioxide emissions in a significant way? Do you observe any evidence that humans can reduce methane emissions in a significant manner?

    I view all the back and forth about which ghg emission to address as akin to argument about the deckchairs on a certain luxury liner. Some folks believe the deck chairs should be in neat geometric rows and others like the chaos patterns that emerge when the chair sitters move things to their personal taste. Either approach is not going to matter much once we start taking on water.

    That said, I think, yes, let’s focus on CO2 with a carbon tax and manage methane emissions with an EPA fine if/when the source of emissions can be identified with enough certainty. No reason why we can’t do two things at once. I can walk and chew gum. No reason to choose one over the other if I want to walk and chew gum at the same time.

    Cheers

    Mike

  4. smallblue,

    Do you observe any evidence that humans can/will limit our carbon dioxide emissions in a significant way? Do you observe any evidence that humans can reduce methane emissions in a significant manner?

    Yes, I think we can and I think we’re already in a position where we’re unlikely to follow one of the higher emission pathways. We’re still not doing enough, and it’s still going to be challenging, but I do think it’s being taken much more seriously, I think we do have viable alternatives, and I think we are starting to see the impact of their implementation.

  5. Chris Smaje says:

    I’d argue strongly against changing paddy cultivation, especially when it’s for local consumption. Only 18% of agricultural methane emissions come from paddy, and it’s vastly more important nutritionally than ruminant meat, the latter being responsible for 74% of agricultural methane emissions. Also, N and P cycling in paddy systems work pretty much as a renewable closed loop, and the social structures of small scale paddy farming mesh well with food sovereingty and nutritional goals. As I think Ken is saying here, we shouldn’t over-emphasize the importance of methane in climate forcing, and inasmuch as we should emphasize it, I think paddy cultivation (especially existing rather than new paddy) comes very low on the list of concerns – much lower than methane emissions from the fossil fuel industry, for example.

  6. Chris,

    I’d argue strongly against changing paddy cultivation, especially when it’s for local consumption.

    Yes, I’m not an expert on this, but I am concerned about climate plans that might impact people who are simply cultivating food for local consumption.

    As I think Ken is saying here, we shouldn’t over-emphasize the importance of methane in climate forcing, and inasmuch as we should emphasize it,

    I don’t want to dismiss the importance of reducing methane emissions when it is possible to do so and when we can do so independently of reductions in CO2 emissions. However, it does have a relatively short atmospheric lifetime, and so any process that is not increasing its methane emissions is essentially not contributing to long-term climate warming.

    I think paddy cultivation (especially existing rather than new paddy) comes very low on the list of concerns – much lower than methane emissions from the fossil fuel industry, for example.

    Based on my understanding of the topic, I would agree. I think we can reasonably expect the fossil fuel industry to invest in processes that don’t emit methane into the atmosphere.

  7. “Yes, I think we can and I think we’re already in a position where we’re unlikely to follow one of the higher emission pathways.”

    I hear this and think it sounds good, but when I look at the pattern/trend of CO2 accumulation in ocean and atmosphere I do not see evidence that we have done anything significant.

    https://www.climate.gov/news-features/understanding-climate/climate-change-atmospheric-carbon-dioxide

    “Global atmospheric carbon dioxide was 409.8 ± 0.1 ppm in 2019, a new record high. That is an increase of 2.5 ± 0.1 ppm from 2018, the same as the increase between 2017 and 2018. In the 1960s, the global growth rate of atmospheric carbon dioxide was roughly 0.6 ± 0.1 ppm per year. Between 2009-18, however, the growth rate has been 2.3 ppm per year. The annual rate of increase in atmospheric carbon dioxide over the past 60 years is about 100 times faster than previous natural increases, such as those that occurred at the end of the last ice age 11,000-17,000 years ago.”

    It kind of comical to me that you are slightly unhappy with the reporting/spin/presentation by NYT of the emissions and I certainly agree with you that their original presentation about the “end of century” framing is very inaccurate. You and I would agree that the “second half of the century” framing is also inaccurate. In both cases, the impact of the NYT article may to be allow folks to read the paper of record and feel like our climate warming problems are decades away when that is almost certainly incorrect.

    I feel in a similar way that your framing of progress to avoid the highest impact scenarios is too rosy and again will allow folks to feel like we are doing enough when the evidence that I see does not suggest that we are engaging in changes that would bring us to a net zero status and net zero is where we need to be, right? Does it make sense to include a simple observation that “we need to get to net zero status asap to stop the warming and we are nowhere near that status as measured by the global atmospheric numbers.” I think that is where the rubber meets the road, so to speak.

    Good work pulling the NYT into presenting concerns about the impacts that we may start to experience in 30 years. I will have left the building by that time, so my observations at that point will likely cease.

    Cheers

    Mike

  8. smallblue,

    I hear this and think it sounds good, but when I look at the pattern/trend of CO2 accumulation in ocean and atmosphere I do not see evidence that we have done anything significant.

    To a certain extent you do need to compare against a counter-factual that we haven’t actually experienced. It is true, though, that we have yet to actually start reducing carbon dioxide emissions, but I think we’re on a better trajectory that we might have been on and I do think we may see peak emissions relatively soon. We should also, though, be careful of unfounded optimism.

  9. as to rice: why not push hard to move the rice growers to one of the cultivars that produce less methane?
    http://www.ciesin.columbia.edu/docs/004-032/004-032.html
    We can walk and chew gum, right? Rice or no rice are not the only options. Transition to low methane emission rice seems like a reasonable idea/option to remember and mention.

    Cheers

    Mike

  10. smallblue,
    I certainly don’t think there’s anything wrong with trying to find alternatives that might emit less methane. However, as Chris pointed out, I don’t think methane emission from rice cultivation should be high on our list of priorities when it comes to looking for sector that could do more to reduce their methane emissions.

  11. CS says “Only 18% of agricultural methane emissions come from paddy, and it’s vastly more important nutritionally than ruminant meat, the latter being responsible for 74% of agricultural methane emissions.”

    I think it’s hard to mention this one without being accused of wanting to take away hamburgers from hard working Americans, but in a way that is similar to the low emission rice cultivars, it may be worth mentioning that we have ways of reducing ruminant methane emissions: https://www.labiotech.eu/in-depth/feed-additives-cattle-methane-emissions/

    I am not sure if we will succeed at reaching net zero and stabilizing climate, but if we do, I am pretty sure that the path to that happy place is not simple, we will have to make many changes to many systems and address the problem(s) in a manner that is more complex than rhetorical. In that vein, I think we should talk about low emission rice cultivars and low emission ruminant feed formulas as important and urgent matters to facilitate.

    Cheers

    Mike

  12. David B Benson says:

    “United Report”
    “future greaters”
    ?

  13. David,
    Good catch, thanks.

  14. Twenty years ago if, globally, methane emissions had been stabilised (reducing emissions) then only cutting CO2 (and N2O, the long-lived gases) very quickly to net zero might have been enough to limit to 1.5ºC or “well below 2ºC”, but that is needed *and* also achieving substantial negative forcing by a combination of methane (and other SLCF) reduction and/or carbon dioxide removal (CDR) is needed. Now, “we” – the richest nations, corporations and persons first and foremost – need to achieve all of the above in combination using all GHG reduction levers.

    Within the Paris ºC limit context, methane reduction effectively acts as fast lever to limit overshoot of “fair share” national carbon quotas (however defined) of the remaining global carbon budget. For richer nations such quotas are rapidly heading toward overshoot so this is a strong international equity basis for urgent methane reduction. Otherwise there is also an intergenerational inequity in failing to achieve substantial methane reduction as it means a tacit (and costly) long-term CDR requirement for these nations to return to a fair share Paris quota level after overshoot.

    The ongoing rise in global methane emissions is alarming because any sustained change in methane flow has a big impact, increasing or decreasing methane-related warming.

    One of the points regarding methane that seems to be little appreciated, even by some climate scientists, is that the climate system temperature response behaviour of a sustained new flow (~ ongoing pulses) or a reducing flow is very different that of a single the pulse with its peak at 10 years from emission.

    By comparison, a sustained change in flow has a strong effect that has an impact of about 25x that of a single pulse and this impact takes about 30 years to taper off. That means that the result of any permanent methane reduction in 2021 will only have its full effect by 2050.

    This is why the IPCC SR15 illustrative pathways to meet 1.5ºC show most methane reduction (fossil and agri) taking place in this decade, by 2030, and levelling off the mitigation rate thereafter to reach about 50% of the 2010 level by 2050, when CO2 is passing through net zero. Adding more, later CDR, through BECCS, is the main modelling balance for not achieving methane reduction.

  15. Paul,

    One of the points regarding methane that seems to be little appreciated, even by some climate scientists, is that the climate system temperature response behaviour of a sustained new flow (~ ongoing pulses) or a reducing flow is very different that of a single the pulse with its peak at 10 years from emission.

    Maybe I misunderstand you, but if you’re suggesting that there is some confusion about the temperature response to methane emissions, then I agree. The warming due to methane depends strongly on the emission profile (i.e., rising, flat, falling) which is not the case for CO2.

  16. Not that. There is an increasing rhetoric, especially in livestock and gas vested interests, around memes including “methane is a short-lived gas”, as if it “disappears” after we delaying reductions is okay, and “biogenic” methane, as if agri methane is not important. Now that cutting methane is very important these interests have woken up to action-delaying tactics just as the coal and then oil industry did.

  17. Paul,
    Yes, I see what you mean, thanks. I find this quite a tricky issue, because it is clear that the warming impact of methane differs from that of CO2 and it’s worth, IMO, making this difference clear. However, there are some who are using this to then – as you say – to develop action delaying tactics.

    In a sense, it seems similar to the net-zero debate. Scientists present information and organisations with vested interests then utilise that information in ways that suits their agendas.

  18. Yes exactly that.
    [Apologies for my distracted typing above, but you interpreted correctly anyhow.]

  19. C Jarzbek says:

    Cutting methane emission has twice the effect one must take into consideration. After CH4 enters the atmosphere all of the O2 molecules have an affinity for it as in …. CH4 + 2O2 → CO2 + 2H2O.

    So for every molecule of methane you emit, you end up with a molecule of CO2

  20. C Jarzbek,

    So for every molecule of methane you emit, you end up with a molecule of CO2

    Yes, that is true. However, the amount of methane we emit is actually quite low when compared to the amount of CO2 we emit. So, the dominant warming effect is when it’s methane, not when it’s CO2. Also, if the source is biogenic, then this is not a new carbon (i.e., it was already part of the carbon cycle). Methane release associated with fossil fuel extracting is adding a new carbon and hence, ultimately, adding CO2 to the atmosphere.

  21. Chris Smaje says:

    Thanks for the informative discussion. If indeed it’s necessary to reduce methane emissions to hit CC targets presumably there should be some prioritisation. Different rice varieties might be worth trying, but I still think spending resources persuading smallholder farmers with minimal climate impact to change their ways should come low on the list and would give a poor return on investment. Maybe there’s a stronger case with beef farming, but it seems to me the main pushback here is again from the more marginal/holistic pasture-based sector which, though it sometimes inflates its claims, maybe has a point about the low impact of well managed grasslands. In any case, it’s a very minor vested interest compared to fossil fuel producers and consumers who seem to prefer to identify anything – rice, beef, tree-planting – other than fossil fuels as the way forward. Presumably Ken’s point about biogenic methane in the agricultural sector is also relevant here, lowering its climate impact relative to fossil fuels?

  22. I did write a post about agricultural emissions, which quoted a paper as saying:

    reducing methane emissions at the expense of CO2 is a short-sighted approach that trades a near-term climate benefit with warmer temperatures for every year thereafter

    and that

    If strong efforts are made to reduce agricultural emissions but prove expensive—in terms of monetary costs, political capital, public goodwill, or individual effort—and detract from efforts to eliminate fossil CO2 emissions then we will be climatically worse-off.

  23. “Ken’s point about biogenic methane in the agricultural sector is also relevant here”

    Is it? It seems to me that we have to remember that the carbon cycle (and other greenhouse gas cycles) may function differently on a warmed planet. I think at some point, every bit of ghg in the atmosphere is simply a problem for us and the source of each bit becomes an academic question if we continue to see the raw numbers rise.

    Here’s an example of how things can change in the “natural” cycles in ways that we need to keep in mind:
    https://www.theguardian.com/environment/2021/apr/30/brazilian-amazon-released-more-carbon-than-it-absorbed-over-past-10-years
    https://www.nature.com/articles/s41558-021-01026-5

    Ken and/or others may not be particularly concerned about these potential events that could happen at some future point, but that brings us back full circle to the criticism of the NYT for framing these matters as a future issue when they really are a present time issue with deep roots in our past actions and our lack of willingness to make changes that are required to stop the warming.

    I would also remind folks that over and over, the headline stories are about how the changes are happening faster/earlier than predicted/expected. Our species evolved in a climatological sweetspot of relative stability, but I think we are well on our way to pushing the planet to a different state and the next sweetspot of relative stability might not be to our liking.

    What’s wrong with being conservative about the impact we are having and following the precautionary principle?

    Need a recent example of “faster/earlier than expected”? Here you go: https://www.livescience.com/doomsday-glacier-close-to-tipping-point.html

    I agree with Ken that we should be concerned about unfounded optimism. It’s a good idea to be aware when unfounded optimism is apparent and maybe point that out.

    Maybe I am wrong about all or some of that. Maybe we will see the peak emissions happen soon and then start to decline as Ken believes will happen. I hope to live to see that. I think most of us agree that the peak emission moment has not happened yet.

    Here is one of the raw numbers that I track:

    March CO2

    Mar. 2021 = 417.64 ppm
    Mar. 2020 = 414.74 ppm

    That looks like 2.9 ppm increase yoy. That number gives me no comfort or joy.
    co2.earth

    If you are happy or content with that number and the trends that you discern, I am happy for you.

    Cheers

    Mike

  24. small,

    Ken and/or others may not be particularly concerned about these potential events that could happen at some future point,

    No, this is not the case. However, if we’re worried about some of these potential events, then a key thing is to limit long-term warming, and the key driver of long-term warming is CO2 emissions. This is not to suggest that we shouldn’t bother reducing methane emissions. We should also do this. However, we should be aware that the warming impact of methane and CO2 are different and that if we are worried about the impact of long-term warming, then the key GHG is CO2.

  25. I end up in the same spot with you that you arrived at with the NYT. You think and post about “a key thing which is to limit long-term warming.” I think that short and midterm warming factors are also significant and should be discussed. I appreciate that you engaged in the discussion and I don’t want to quibble with you, just as you stopped quibbling with the NYT at a certain point.
    Keep up the good work,
    Mike

  26. Chris Smaje says:

    So…my point about biogenic methand was more question than statement. But if it’s the case that we need to slash both methane & CO2 emissions very rapidly, bear in mind that the local agricultures that have developed in low energy situations have methanogenic elements like paddy or ruminants. If the poor small-scale farmers practicing them are expected to cut these elements out, this may create some difficulties for feeding ourselves in a low carbon world, and would certainly have to be accompanied by richer more urban people likewise avoiding emissions – no fossil fuelled cars, aeroplanes, boilers, blast furnaces etc. Otherwise we’ll probably have to figure in growing legitimation failures of goverments and political revolutions to the already heady climate change brew

  27. Chris,
    Given that long-term warming depends primarily on how much CO2 we emit in total, achieving our climate targets (1.5C, for example) would primarily require slashing CO2 emissions. Given the warming impact of methane, this would probably also require that we stop increasing methane emissions, but may not require that we also slash methane emissions. Of course, if we were able to easily do so, then there would be climate benefits, and we should certainly be expecting fossil fuel produces to commit to reductions in methane emissions. I don’t, though, think we should be expecting the same of small-scale farmers and there probably isn’t even a need to do so.

  28. Chris Smaje says:

    Thanks for that clarification Ken. That seems the sensible approach to me. I’m worried that if the pressure of climbing emissions fosters too indiscriminate an approach to methane reduction in the agricultural sector, it could have very counterproductive consequences.

  29. Chris says “If the poor small-scale farmers practicing them are expected to cut these elements out…”

    Incentives can be used to help small scale farmers reduce their biogenic emissions. I can’t think of a reason why a first world nation or a national government would not be able to subsidize low emission cultivars of rice or subsidize feed and/or feed supplements that reduce emissions from ruminants.

    I can’t think of any compelling reason that small scale and developing world farming could not take part in a wide-ranging approach to reducing emissions that produce global warming. It also seems like a good idea that first world nations should foot the bill on the incentives and technology that would help third world and small scale farmers reduce their personal emissions in a rather painless manner.

    Cheers

    Mike

  30. Watching a coral reef die as climate change devastates one of the most pristine tropical island areas on Earth
    https://theconversation.com/watching-a-coral-reef-die-as-climate-change-devastates-one-of-the-most-pristine-tropical-island-areas-on-earth-159792
    When I read a story like this one I think maybe it makes sense to address methane emissions to reduce global warming damage that is happening now.
    Cheers
    Mike

  31. Joe Clarkson says:

    It also seems like a good idea that first world nations should foot the bill on the incentives and technology that would help third world and small scale farmers reduce their personal emissions in a rather painless manner.

    I disagree. Small scale farmers in undeveloped nations have virtually nothing to do with excess carbon emissions. I fear that if first world people foot the bill for token carbon emissions reductions from those farmers they might believe that they were actually doing something significant to mitigate climate change and thereby distract themselves from getting their own houses in order.

    It is industrial civilization and the people to live in modernity that have emitted the vast majority of excess greenhouse gases and their high emission levels are ongoing. Only when first world nations have reduced their emissions to the level of undeveloped nations (presumably by abandoning modernity), should they even think about providing incentives for other low emitters.

    It is also likely that once first world nations reduce their emissions by 95%, or more, they will not be able to afford the incentives anyway. They will be too poor.

  32. Ben McMillan says:

    Although figures are variable, most emissions from beef/dairy are not methane (N2O& land use CO2 are big).

    The cooked-up outrage over Beef being cancelled highlights the issues going forward though…

  33. Ben,

    Although figures are variable, most emissions from beef/dairy are not methane (N2O& land use CO2 are big).

    Yes, I agree that we mustn’t forget that there are emissions of long-lived GHGs from beef/dairy.

  34. Joe,
    I don’t agree with the last part of your comment, but I do agree that maybe the developed world should primarily focus on reducing their own emissions, and leave the developing world how to decide for themselves how to progress.

  35. Ben says “The cooked-up outrage over Beef being cancelled highlights the issues going forward though…”

    Exactly. The culture wars pushback against addressing global warming is astounding in its stupidity. Plus, we have corporate entities still hard at work identifying new oil fields for development: https://www.cnn.com/2021/05/03/africa/namibia-oil-exploration-intl-cmd/index.html?utm_term=1620037641627fa2de20e3322&utm_source=cnn_Five+Things+for+Monday%2C+May+3%2C+2021&utm_medium=email&bt_ee=sBL%2F8Zxz%2BupmHXnXpd8UxRNSHUFEWXn3UjcqXCNYP5mNxhUYupy3IDss12DJRxBq&bt_ts=1620037641629

    I think these are the two big drivers that make progress on global warming reduction so slow. Maybe there are more, but it seems to me that culture war stupidity and profit-chasing are the big ones.

    Thanks for pointing out that methane is not the only emission with beef and dairy. The same is almost certainly true with a lot of non-meat agriculture. I have been clear that I think broadening our efforts to reducing greenhouse emissions as a class makes sense to me because whether the particular emission is long or short-lived in the atmosphere may be less important in some respects than the simple fact that the emission will produce additional warming on a planet that is already changing from the current level of warming.

    Cheers,
    Mike

  36. It seems to me that we should grab the low-hanging fruit in terms of ghg emission reduction by implementing relatively cheap and easy solutions like ruminant feed additives and low emission rice cultivars and use these solutions in the first world in a responsible manner, then first world nations should share these solutions and cover the costs or pay for incentives to help the developing world join us in addressing global warming.

    There is a lot of potential conflict in questions about whether first world nations should clean up their act first, but to me, that seems like a new version of a stupid, self-destructive culture wars and that might disappear if we decided to act as if we are all in this together. No emission reductions that we might manage in such a manner seems insignificant to me.

    I dream of such things.

    Cheers
    Mike

  37. Mitch says:

    About 20 to 25% of methane emissions are from fossil fuel:
    https://www.noaa.gov/media-release/study-finds-fossil-fuel-methane-emissions-greater-than-previously-estimated

    Unfortunately the study did not separate out the different microbial sources. Nevertheless, a big effect can be achieved by reducing the fossil fuel number.

  38. EPA moves to restrict powerful planet-heating gases in air conditioners and fridges

    “In the first move by Joe Biden’s administration to directly cut a greenhouse gas, the EPA has proposed a rule to drastically reduce the production and import of HFCs in the US by 85% over the next 15 years. The step is a significant one as Biden seeks to cut total US emissions in half by the end of the decade.”

    We can and should address global warming in several ways at the same time. This article says EPA is about to slam the door on some refrigerants that are potent global warmers. That does not mean that we can’t also move forward on reducing emissions for agriculture and beef/dairy industry. We can and should. None of that means we should not move forward on reducing CO2 emissions. CO2 is the big dog and the industries that profit from poorly constrained CO2 emissions will fight tooth and nail to wring the last dollar of profit out of fossil fuel reserves even if it kills lots of living things.
    Cheers,
    Mike

  39. Chris Smaje says:

    Mike writes: “There is a lot of potential conflict in questions about whether first world nations should clean up their act first, but to me, that seems like a new version of a stupid, self-destructive culture wars and that might disappear if we decided to act as if we are all in this together.”

    I don’t necessarily disagree with that, but the people who have almost all the power to make that decision are in the rich countries (and a couple of the richifying ones) – and quite simply they haven’t made that decision to date. Until they do, I doubt there will be much progress, and railing at the short-sightedness of poor country governments or poor farmers will achieve little. As Joe says above, if they do make the decision, I think they’ll find themselves less rich pretty quickly, and this does strike me as quite a problem – an open access tragedy, essentially.

    On a separate point, it’s important to distinguish between the impact of the present livestock industry and of livestock in low energy smallholder systems. In the case of the latter, I think the emissions mostly are methane?

  40. Vidar says:

    Wouldn’t accumulation of heat in the oceans make CO2 caused warming to be even more delayed than a decade? And therefor the effect of reduced CO2 emissions will take longer than a decade to respond?

    What I think of, is when the ocean becomes warmer, it emits more water vapor, which in turn does its magic to increase the heating furter. Even if water vapor is a condensable gas, and for that reason is a short lived gas, it is constantly being emitted from the water surface, making it a ‘long lived’ gas.

    Removing CO2 from the atmosphere is probably a dead end. Not because it doesn’t work, but for one it takes redicolus amounts of energy per CO2 unit, while the atmosphere consist og approx 3100 Gt of CO2, where at least 20% of that must be removed to reach 1990 levels. That assumes zero emmisions from day one (which is not going to happen any time soon).
    Secondly, removal of CO2 will most probably be an excuse to keep digging for more oil and coal.

    I’m not an expert. Just thoughts.

  41. Vidar,
    A key point is that there is a difference between what happens if we fixed atmospheric concentrations and stop emitting. If atmospheric CO2 concentrations are fixed, then we would keep warming for a long time because of the large heat capacity of the oceans. However, if we stop emitting CO2, atmospheric CO2 concentrations actually drop as the natural sinks continue to take up some of our emissions. A consequence of this is that this continue uptake balance the delayed warming so that warming soon stabilises. This is essentially the case if we consider individual pulses of emissions. The initial pulse increases atmospheric CO2 and causes warming. However, some of this pulse of emissions is taken up by the natural sinks so that the peak warming due to this pulse of emission happens relatively quickly (within about a decade, or so).

  42. Bob Loblaw says:

    “Even if water vapor is a condensable gas, and for that reason is a short lived gas, it is constantly being emitted from the water surface, making it a ‘long lived’ gas.”

    …and it is constantly being condensed and rained/precipitated out. And the rates balance, in manner where the mean atmospheric quantity is a function of temperature, not evaporation or precipitation rates. Pump more water vapour in, more will precipitate out. Hence, in the long term, it is a fixed quantity (global mean), unless something else comes along to change global atmospheric temperatures (e.g., CO2, solar forcing, etc.). At that point, it becomes a feedback, not a forcing.

  43. Russell says:

    Given the UN report’s admonition that:
    “slashing emissions of methane… is far more vital than previously thought.”

    More attention should be paid to methane from dammed rivers. Prodigeous amounts of organic matter are trapped and converted to methane by anaerobic fermentation in the warm depths of reservoirs created by tropical dam projects , including those on the Nile and Mekong.

    Methane emission from Lake Nasser, behind the Aswan Dam, reportedly accounts for half of Egypt’s carbon footprint, and the latest Nile dam may do the same for Ethiopia. Needless to say, some of the water in both reservoirs will find its way to rice paddies.

    On the bright side, methane from surface reservoirs plays a far greater role in radiative forcing elsewhere in the solar system:

    https://vvattsupwiththat.blogspot.com/2021/05/nasa-releases-chilling-kraken-data.html

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