Agricultural emissions

There’s a really nice recent paper by John Lynch, Michelle Cain, David Frame and Ray Pierrehumbert on Agriculture’s Contribution to Climate Change and Role in Mitigation Is Distinct From Predominantly Fossil CO2-Emitting Sectors. It’s largely discussing why there are important differences between carbon dioxide (CO2), which is a stock pollutant, and methane (CH4), which is predominantly a flow pollutant.

The basic point is that the emission of CO2 increases the stock, which leads to a long-term increase in atmospheric concentrations and, consequently, to warming that will persist for a very long time. Methane, on the other hand, has a short atmospheric lifetime, decaying within decades to CO2 and water. Given that – for agricultural emissions – the carbon comes from plants, this doesn’t add a new carbon to the system, and hence doesn’t increase the stock. This isn’t strictly true for methane from natural gas, since that does add a new carbon to the system, but this is relatively small when compared to direct CO2 emissions from fossil fuels.

Left: A single emissions pathway (left) reported as CO2-equivalents using the 100-year Global Warming Potential. Right: How the resulting warming depends on the gas-specific composition (credit: Lynch et al. 2021).

The key figure in the paper is the one above. The left-hand panel shows an example of an emission pathway based on using CO2-equivalents using the 100-year Global Warming Potential (GWP100). The right-hand panel shows the actual warming we would experience for different gas-specific compositions. CO2 warming (dark blue line) peaks when emissions gets to zero, but then remains at this level well after emissions have ceased (it’s essentially irreversible without some kind of artificial negative emission technology).

Methane (yellow line) initially produces more warming than would be expected based on its CO2-equivalence. However, when emissions start to go down, there is cooling, which continues well after emissions have ceased (for completeness, the pink line is 50% methane, 50% CO2, while the green line is N2O which has a reasonably long atmospheric lifetime).

The key point is that if one is using GWP100 to estimate CO2-equivalence, you would predict warming profiles that would be quite different to what would happen in reality. You would under-predict the impact of methane emissions initially, but then over-predict its impact later on.

The reason this is important is because any emission reduction pathways are likely to involve trade-offs. Consequently, as the paper highights,

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


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.

Essentially, the emission of a stock pollutant (CO2) leads to warming that will persist for a very long time, which is different to the impact of a flow pollutant (agricultural methane). The latter clearly does produce warming and, in fact, leads to more warming in the near-term than simple CO2-equivalent estimates would suggest. However, this warming would stabilise if emissions were to stabilise (unlike CO2) and can be reversed if these emissions are reduced (also, unlike CO2).

So, it would seem important to be aware of these differences when thinking of how best to decarbonise. Any strategy that prioritises short-lived pollutants over long-lived pollutants runs the risk of committing us to future warming that is essentially irreversible and that we could have avoided if we’d prioritised differently.

This isn’t to suggest that we should be ignoring the short-lived pollutants. They can have a large near-term impact which may be important if we wish to avoid crossing certain warming thresholds. There may also be other reasons for reducing these emissions (land use change, for example). I just happen to think that if we’re trying to assess the impact of different greenhouse gas emissions, it’s important to use a metric that properly represents this.

Links: (these are additional resources that might be useful)
Agriculture’s Contribution to Climate Change and Role in Mitigation Is Distinct From Predominantly Fossil CO2-Emitting Sectors, new paper by Lynch et al. (2021)
Losing time, not buying time, Realclimate post by Ray Pierrehumbert making the same basic point (from 2010).
Methane, a post I wrote in 2019 about the impact of methane.
Guest post: A new way to assess ‘global warming potential’ of short-lived pollutants, Carbon Brief guest post by Michelle Cain.
Methane and things, another post I wrote last year trying to explain the difference between metane emissions and CO2 emissions.

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180 Responses to Agricultural emissions

  1. I’ve had a number of Twitter discussions about this and it surprises me how contentious this can be. It does seem that some see this as an attempt to excuse some emissions and hence, delay decarbonisation. I can see why they might think this. However, I do think it is also true that too much focus on short-lived GHGs could end up with us emitting more of a long-lived GHG, the warming from which would essentially persist forever (in human timescale terms). So, I think that it would be useful if those who object to the arguments above could explain how we avoid this.

  2. dikranmarsupial says:

    “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 ”

    good job humans are good at trade-off between short and long term costs/benefits… oh, … hang on… ;o)

  3. billbedford says:

    What are the units on the y axis of the right-hand graph? mK? is that 0.001 degrees Kelvin?

  4. bill,
    Yes, it’s milli-Kelvin. The units on the left-hand graph are million-tonnes of CO2-equivalent.

  5. Ben McMillan says:

    Agriculture is also inextricably tied up with other environmental issues about land use/biodiversity, and water use and pollution, and local air pollution impacts. And appallingly complicated in political/equity terms.

    So there are lots of reasons to be pretty cautious about taking a AGW-focused approach dealing with agriculture, unlike with e.g. electricity, where normally carbon-pollution is actually the biggest problem.

    But there seem to be some relatively easy wins in certain places, e.g. breeding and diet of cattle can make a big difference to methane emissions. More moderate meat intake also seems like a clear winner for a number of reasons.

    I’d be inclined to prioritise ecosystem protection in the agriculture sector, given the kind of stupidity possible in terms of e.g cutting down forests to grow ‘sustainable biofuels’.

  6. Ben,

    Agriculture is also inextricably tied up with other environmental issues about land use/biodiversity, and water use and pollution, and local air pollution impacts. And appallingly complicated in political/equity terms.

    So there are lots of reasons to be pretty cautious about taking a AGW-focused approach dealing with agriculture, unlike with e.g. electricity, where normally carbon-pollution is actually the biggest problem.

    Indeed, I agree. That was what the end of my post was trying to suggest. My view is mostly that *if* someone is going to take an AGW-focused approach, then using a metric that better represents the impacts of the different greenhouse gases (GWP*) is better than using one that doesn’t represent their impacts very well (GWP100, for example).

  7. So, a redundancy paper on CH4 vs CO2, this one purportedly focused on agricultural CH4 emissions. Same conclusion: no form of CH4 reduction will replace FF emissions reduction of carbon in the long term. These authors have now said as much over several papers now. I hope that the IPCC gets this memo in time for AR6.

    Next up? Human methane emissions (e. g. butt plugs will not work as a long term solution), belching and breathing.

    Meanwhile, back at the ranch, CO2, CH4 and NO2 continue to increase in the atmosphere.

    The only thing that humanity has done to cool the globe, to date, is to release ever more air pollutants.

  8. EFS,
    I think the message is getting through, even if not everyone is getting it (yet).

  9. “I think that it would be useful if those who object to the arguments above could explain how we avoid this.”

    Hmm… CO2 powered long term global warming or methane powered short term heat bursts? Would I rather be shot or hung?

    My sense is that you are choosing a pretty mainstream, comfortable and deferential position that allows you to look at the comparative benefits of splitting the baby when the smart move might be to look for more radical solutions, like pushing for an agricultural revolution that might be able to maximize food stuffs and other benefits.

    I don’t know if the permaculture agriculture approach could live up to its hype, but it might be worth including in discussion when trying to evaluate whether to be hung by CO2 or shot by methane:



  10. Chubbs says:

    I can see why the paper raised some hackles. The GWP100 value for methane is 33, so the chart is comparing 33 CO2 for every single CH4. Yes, one can make a very good argument for using a lower # to better account for methane’s lifetime. Doesn’t mean I want to give methane or agriculture a free pass. Would want to look at other issues as well. If there is a cost-effective way to reduce methane and other GHG from agriculture, I am all for it.

  11. Chubbs,
    It’s not so much using a lower, it’s that the number doesn’t really mean what people think it means. It’s really a comparison between the radiative impact of, for example, methane compared to CO2 integrated over a certain time period. Given that methane decays with time, the problem becomes (as the figure in the post illustrates) that this number under-represents the warming impact of methane at early times, but over-represents it at later times.

    This paper by Michelle Cain suggests an alternative metric (called GWP*, which I’ve mentioned in earlier comments, but not defined). The CO2 warming equivalent emission becomes:

    E_{CO_2 we} = GWP_{H} \left[ r \dfrac{\Delta E_{CH_4}}{\Delta t} H + s E_{CH_4} \right],

    where GWP_{H} is the original global warming potential integrated over H years, the first term in brackets is basically the change in methane emissions over some time period (typically the past 20 years) multiplied by r and the integation timescale H and the second term is a stock term that takes into account longer-term methane-driven warming. The variables r and s are typically 0.75 and 0.25.

    As Michelle Cain pointed out on Twitter, when you use GWP* you get a much better fit to the actual warming than you get if you use GWP20, or GWP100.

  12. wmconnolley says:

    > if one is using GWP100 to estimate CO2-equivalence, you would predict warming profiles
    This doesn’t make sense. GWP100 is a single number; you can’t turn it into a time-dependent profile.

  13. WMC,
    I (obviously) didn’t mean just using GWP100. GWP100 is used together with the emissions to estimate CO2eq emissions, which is essentially what the left-hand panel in the figure is illustrating. The problem is this doesn’t then provide a particularly good estimate of the subsequent warming profiles.

  14. wmconnolley says:

    But that’s hardly surprising. It isn’t supposed to.

  15. WMC,
    Yes, I know that, you know that, but a lot of people appear not to know that.

  16. Chubbs says:


    Yes I understand that GWP overstates the value of controlling methane,on long time scales, still we can’t let methane continue to increase in the atmosphere. To me the paper strayed too far from technical issues. They lost me when they argued that reducing agriculture emissions is going to detract from reducing fossil fuel burning. A different paper. is needed to argue that point convincingly.

  17. Chubbs,
    I see what you mean. I agree (and I think paper says something similar) that when emissions are increasing, the metrics give similar estimates. So, the strategy we employ while methane emissions are increasing may well end up being the same, irrespective of the metric. The issue, though, is whether we really need to aim for zero methane emissions, as we almost certainly do for CO2. I don’t think the paper was suggesting that reducing methane emissions would detract from reducing fossil fuel emissions, but that it could and that this could be worse, climatically.

  18. IMHO, this has more to do with the 2015 Paris Accord and NDC’s. Carbon trading or gaming the system to offshore ones commitments. And CH4 reductions is one such vehicle to do an end around and cheat the well intentioned but rather naively implemented NDC’s. GWP100 is the currently used NDC bookkeeping system afaik.

    I am such a cynical cuss.

  19. Andrew J Van Wagner says:

    ATTP, I follow the climate debate pretty closely, so it’s interesting that I’ve never seen short-lived vs. long-lived GHG in any sort of conflict.

    I know that natural gas involves methane-release from the wells:

    But that gas is absolutely essential as a “bridge-fuel”:

    One scientist told me this:
    If you instantaneously tried to go to near-100% renewables, your costs for storage would explode. But, there are all sorts of pathways over a small number of decades in which the costs do not explode, and increasingly it is appearing that, rather than a net-carbon-zero energy system costing a bit more than the modern system (I used to cite order of 1% of economy), it will be cheaper than that and perhaps free, and in any full accounting including the damages of climate change will be notably cheaper than the modern system. I have often highlighted electrifying as much as possible, building a lot of renewables, initially stabilizing the grid with gas turbine peaker plants, and using that to squeeze out most of the fossil-fuel emissions, then replacing the gas turbines fairly late in the process. But, there are lots of other paths. A solid and fairly deep literature shows that there is no need for storage costs to explode, but that it takes some time, which means that delay is highly costly.

    They added:
    By “free”, I meant that direct costs of the new system may be equal to or less than the direct costs of the existing system, if we ignore the benefits of avoided climate change. Including the benefits of avoided climate change, the new system will be much cheaper. The change in thinking is driven in large part by the remarkable progress of renewables. See the attached—note the comment on storage costs for regions that import gas. If you note how rapidly storage prices have been dropping, with no sign of bottoming out yet, this is interesting.

  20. Andrew J Van Wagner says:

    The “attached” in my previous comment refers to this:

    This is the gist of it:

    “New wind, solar and battery projects are getting so inexpensive that they rival the cost of building new gas or coal power plants in most of the world, according to a new report.

    The study, released today from Bloomberg New Energy Finance (BNEF), explored where renewable energy projects are competitive, and how dramatically their prices are falling.

    A solar or wind farm is now the cheapest kind of new power plant for two-thirds of the world’s population, according to BNEF. Those areas represent up 71% of gross domestic product and 85% of energy generation.

    The continued lowering of prices for carbon-free source of energy, like wind and solar, matters because new projects will be in service for decades, affecting the trajectory of greenhouse gas emissions. Cost competition from these sources also opens the possibility of retiring existing coal or natural gas plants early.”

  21. Andrew,
    In this context, the issue with natural gas isn’t so much its use as a fuel, its the inadvertant release of methane directly into the atmosphere. Over short periods of time, it is a powerful greenhouse gas and if natural gas is to be used a bridge fuel, it would be better to minimise the unnecessary methane releases associated with the capture of natural gas.

  22. jacksmith4tx says:

    Here’s my story from living on the edge of the grid.
    I installed a 6.7Kw PV array back in 2012 and it’s my experience that without a drastic reduction in my usage I would have had to build a at least a 10Kw system to reach a net zero balance (using net metering). But I did manage to slash my consumption over 50% by a combination of actions: Zoned heat and cooling, On demand hot water, air dried laundry, LED lights, induction cooking along with updated insulation, attic ventilation.
    As of today I have a $2,013.12 credit balance and I haven’t had a electric bill since March 2012 so I stand as an example of how it can be done. I think the real tipping point will come when V2G(vehicle-to-Grid) rolls out combined with 100KWh car/truck batteries and Demand response

  23. I have not absorbed what this paper and blog post is about yet. I am currently trying to become a little more fluent with the issues around global warming and agriculture, so I am reading and processing this kind of article.

    My initial read on this article is that the authors may be trying to introduce a lot of nuance and complexity into discussion of an industry that needs to be revamped in a major way to fit into a future net zero or carbon negative world.

    The authors say “Energy-use CO2 from either agricultural operations (e.g., tractor fuel) or embedded in inputs (e.g., fertilizer manufacture and transport) can also be included as food system emissions, but are highly uncertain…”

    Well, okay. Yes, the energy use CO2 may be highly uncertain at this moment, let’s do a little work and take some of the uncertainty off the table. First, on tractor fuel, if we can imagine a future where trains and trucks are moving without burning fossil fuels and fit into a net zero economy, it should be possible to imagine and remove levels of uncertainty from the question of CO2 outputs fro agricultural operations. I don’t think this is rocket science. It’s science and technology, but it’s not like building a space station.

    Second, on the question of CO2 emissions embedded in inputs, let’s get real. The actual number may be uncertain, but it is a big number. I think it is a much bigger number than the tractor fuel production number and it is much harder to reduce from what I know about industrial agriculture. Here are some links that show that we have understood this for a long time.

    I think this paper and discussion may be leading us into the deep weeds about agriculture and obscuring the kind of fundamental changes to global agricultural practices that exist on the fringes of a highly industrialized and oil-based food system.

    I would also note that this system is primarily a for-profit and unsustainable system that may exert significant resistance to conversion to anything very different from the current model. Some postion of the investments and “reserves” in our oil for food and profit system could end up being stranded in a conversion to a net zero sustainable food system for a small planet, if such a conversion is possible.

    Am I missing something big and important about CO2e agricultural emissions in this paper and discussion that it makes sense to have no discussion of the underlying premise that our foodstuffs are essentially converted from fossil fuel inputs in the current system?


  24. I am baffled by the confusion and discussion that accompanies the emissions reduction project when we step up the emissions situation with a minor level of complexity – the fact that CO2 and the other substances lumped together as CO2e have different warming characteristics and average lifetimes in the atmosphere. The important point is that these are substances that are emitted to a large extent as a byproduct of human industrial activity and they all create additional warming in a time when warming is easily shown to be a problem.

    Unless there is a compelling reason to to treat them differently, why should we? I think the emission reduction process for CO2 is easily expanded and applied to the CO2e gases. This is not a situation where we need to decide whether to reduce CO2 or CO2e emissions, we need to reduce them all.

    I think I am right about that suggestion and if a paper like this one creates a lot of confusion and new questions about how to proceed in the project to greatly and quickly reducee CO2 and CO2e emissions, I have to ask, hmm… why and how did that happen? Who benefits from increasing confusion about our large emission reduction project? Are the beneficiaries funding the research that splits hairs that don’t need to be split?


  25. Mike,
    One reason you might want to treat them differently is that reducing emission of fossil fuel carbon reduces future warming, and getting fossil fuel carbon emissions to zero stops future warming, but doesn’t reverse it. On the other hand, reducing agricultural methane emissions can lead to cooling and getting agricultural methane emissions to zero would actually reverse a lot of its past warming. You might argue that this is good, but is it fair? Expecting one sector to simply do enough stop future warming while expecting another sector to reverse past warming, especially given that the main reason we have increasing atmospheric CO2 concentrations is because of fossil carbon emissions, not agricultural emissions.

    Also, can we actually get agricultural methane emissions to zero? As I understand it, agricultural methane emissions aren’t only from livestock. There are other agricultural practices that result in methane emissions. So, if we don’t need to get agricultural methane emissions to zero to stop global warming, should we be aiming for this?

    There may well be reasons for doing so, but I do think we should do so while be aware of the different impact of fossil carbon emissions and agricultural methane emissions.

  26. Andrew J Van Wagner says:

    ATTP, do you agree with what Raymond Pierrehumbert said here:

  27. Andrew,
    I normally agree with what Ray says, but that appears to be Noam Chomsky.

  28. Andrew J Van Wagner says:

    Does anyone here know which “hothouse” study (4.5 to 5 degrees above preindustrial) Chomsky is citing here?

  29. Andrew J Van Wagner says:

    ATTP, just take a listen. It’s Ray’s words. 🙂

  30. Andrew J Van Wagner says:

    *4 degrees to 5 degrees above preindustrial

  31. Andrew,
    I can’t quite work out what Ray is actually meant to have said.

    The “hothouse” paper is probably this Steffen et al. paper, which probably goes a bit too far. Richard Betts was somewhat critical in this article.

  32. Andrew J Van Wagner says:

    ATTP, your thoughts on the “panic” thing Ray wrote below?

    Let’s get this on the table right away, without mincing words. With regard to the climate crisis, yes, it’s time to panic.

    We are in deep trouble.

  33. Andrew J Van Wagner says:

    The “hothouse” study:

    –is from the “World Meteorological Association” annual report on the state of the global environment
    –warns about irreversible tipping-points
    –anticipates a “hothouse Earth stabilizing at 4 to 5 degrees Celsius above preindustrial”

    Any clue what that is?

  34. What Ray describe in that article looks correct to me, but whether or not we should panic is a judgement. My personal view is that maybe panicking isn’t the right approach, but I do think we’re leaving things rather late.

    The hothouse earth paper that had a lot of recent coverage it this one. I’m not aware of another one.

  35. Willard says:

    > Any clue what that is?

    Not again, Andrew.

  36. Andrew J Van Wagner says:

    I think that we should hit the panic button. I’m with Ray on this one.

    The alarmists have been vindicated over and over. Something is amiss with the mainstream. Data tells us that the mainstream have been wrong over and over. E.g., on sea-level rise.

  37. dikranmarsupial says:

    It is never time to panic. It only makes effective action even less likely.

    [and preferably know where your towel is at all times]

  38. Willard says:

    > The alarmists have been vindicated over and over

    Then they’re not alarmists, are they?

    You’re peddling “but CAGW,” Andrew. That’s the central square of the Climateball Bingo. This is a thread about a confusion between stocks and flows. Drop it.

  39. “reducing agricultural methane emissions can lead to cooling and getting agricultural methane emissions to zero would actually reverse a lot of its past warming. You might argue that this is good, but is it fair? Expecting one sector to simply do enough stop future warming while expecting another sector to reverse past warming, especially given that the main reason we have increasing atmospheric CO2 concentrations is because of fossil carbon emissions, not agricultural emissions.”

    I would argue that reversing past warming is good and I am enthusiastically in support of aiming for zero methane emissions. If we aim for zero and really work hard at it, we might see methane emissions cut in half or even more. If we aim for and hit zero methane emissions, well, bullseye! so to speak.

    On fairness question: there is so much global unfairness in the responsibility for past and future emissions and the distribution of bad outcomes related to the warming that already exists, that I am inclined to shake my head and roll my eyes when I see/hear fairness raised as a matter that can be used to accommodate continuing emissions of any CO2e gases from any first world industrial process.

    Fairness is in the eye of the beholder.


  40. jacksmith4tx says:

    New research overturns common assumptions about air pollution in Africa’s fastest growing countries.
    “The study, published in Proceedings of the National Academy of Sciences, found that levels of dangerous nitrogen oxides, a byproduct of combustion, in the northern part of sub-Saharan Africa have declined sharply as wealth and population in the area have increased.

    “The traditional paradigm is that as middle and low-income countries grow you often see more emissions, and to see a different kind of trajectory is very interesting,” said Jonathan Hickman, a researcher at the NASA Goddard Institute for Space Studies who was the lead author on the study. “It’s nice to see a decline occurring when you’d expect to see pollution increasing.”

    The reason, according to researchers, is that an increase in pollution from industry and transportation in the area studied — from Senegal and Ivory Coast in the west to South Sudan, Uganda and Kenya in the east — appears to have been offset by a decline in the number of fires set by farmers”

  41. Ben McMillan says:

    I think I figured out what was bugging me about the quotes in the OP.

    Who does this sound like?
    “If strong efforts are made to reduce CO2 emissions but prove expensive—in terms of monetary costs, political capital, public goodwill, or individual effort—and detract from efforts to eliminate malaria then we will be dramatically worse-off.”

  42. Ben,
    That’s a fair comment. I would argue, though, that the issue here is that there’s a tendency to use a simple metric (GWP) to produce CO2-eq emissions for all the different greenhouse gases. Consequently, there’s a tendency to then assume that a cut in a CO2-eq emission of one greenhouse gas is essentially the same as another, when – as the paper indicates – it really isn’t. A better way to put the argument is that if people are going to convert to CO2-eq emissions for the different gases, maybe they should use a more appropriate metric (GWP*) so that you can better compare the warming impacts of the different gases.

    Alternatively, we could just say that they are all different and treat them differently, a bit like we might treat attempts to deal malaria as being different to attempts to reduce CO2 emissions. They don’t necessarily need to compete.

  43. Ben,
    To follow up a bit more, reductions in CO2 and methane are seen to be achieving the same thing (limiting future global warming) and because methane is regarded as a powerful greenhouse gas, there’s a tendency to think that substantial reductions in methane emissions could help to reduce long-term warming, when the opposite may be true if this is done at the expense of reducing CO2 emissions. So, certainly my view is simply that it would be better if this was understood even if there are still good reason for aiming for significant reductions in methane emissions.

  44. Andrew J Van Wagner says:

    [But CAGW. – W]

  45. on panic I come across this comment that matches with my perspective on it:

    Why do people panic, from an evolutionary standpoint?

    This is not about a panic attack or an anxiety problem.I’m referring to the typical reaction when people faced a high stress/dangerous situation. Such as when one hear gunshots. When people panic, they can’t function properly and could even do harm to others at worst and irritate them at best. Why

    It is a flight response and it did not evolve in humans, it is hundreds of millions of years older then humanity and a very effective trait in our ancestral lineages.

    I disagree with your conclusion that

    “… they can’t function properly …”

    Functioning “properly” in an evolutionary context is about one thing only: reproductive success.

    In the context of surviving a life threatening situation, harming or irritating others is not a problem. Politeness, social conventions, decorum are totally unimportant if survival is the only thing that counts. Sitting down an thinking about a decent plan, don’t do it.

    All emergency systems take over to help you survive so that you can keep reproducing. I has one goal: get out of danger no matter what the consequences. Find a save spot to continue your life, producing more offspring.

    That is was is selected for over hundreds of millions of years and the system is just as active in humans as in other animals.

    Sure, keep your towel handy, and of course, thanks for the fishies, but humor aside, I think it is worthwhile to consider why anxiety and panic are experienced by individuals of our species if the panic response had not proven to be of value for surviving to produce offspring.

    Maybe the compromise position is to agree to always reflect on when it makes sense to hit the don’t panic button.



  46. Andrew J Van Wagner says:

    [Mod: Let’s not debate moderation in the comments. We can just move on.]

  47. Chubbs says:

    ATTP, Thinking about your response, a regulatory scheme could give methane emission reduction credits a shelf life. In a fancy system, could start with high multiple CO2 credits per mole and decay to one at the rate methane is converted in the atmosphere.

  48. Ben McMillan says:

    ATTP: Well, it was a bit unfair of me to Lomborg-ify their text. They do explain how a trade-off might arise.

    I think the bit that irritates people is talking about a trade-off between CO2 and methane when the current problem is that we aren’t doing enough on either (even if you think GWP100 overstates the importance of methane).

  49. Chubbs says:

    Building on Ben’s last para. We are in a much better position to control CO2 from fossil fuel burning, and am optimistic we can ramp our efforts. Not as optimistic about methane, doubt we will make much progress in the near future.

  50. Ben,
    Yes, I agree that these can sometimes come across as putting the cart before the horse.

    That may be true, but that doesn’t bother me too much since I do think that the key emission is CO2 and that, given that methane-driven warming is largely reversible, a delay in emission cuts is less of an issue than a delay in the cutting of CO2 emissions. This may be too simplistic, I will admit.

  51. …and Then There’s Physics says:
    February 8, 2021 at 6:49 pm
    I normally agree with what Ray says, but that appears to be Noam Chomsky.

    So do I, but seeing an emeritus philosipher of language delight in zooming about in his high horsepower speedboat may make Ray cross as well.

  52. Dave_Geologist says:

    On panic: I seem to recall reading about studies that found that when you have only a few seconds to do something, such as when a plane or train crashes and there is a slight delay before fire gets into the cabin, it’s the people who panic who get out alive. Usually they can’t remember how they did it.

    A couple of examples come to mind from memory.

    There was a train crash near London where five or ten were killed, but when I saw the photos I was sure there’d been dozens more because one of the carriages had been over-ridden by the locomotive and gutted by fire, presumably from spilt fuel. Turned out everyone got out alive in the seconds before the fire took hold.

    And a couple of bus crashes (I was not involved) when I was working in India decades ago. One over-rode a car and both vehicles were gutted by fire. The car passengers were crushed but all the bus passengers got out, the fire having started in the crushed car. Another rolled down a ravine on the mountain road to Dehra Dun, with no fire but a less happy outcome. The locals were very aware of the low transport safety standards (the nickname for DTC, the Delhi Transport Corporation, was something like Death Travels Closely), and perhaps primed to react when reaction could do you any good.

    Fast and slow thinking, perhaps (or maybe so fast you’re not even thinking). Not too relevant to methane I suppose, since for that and CO2 we have time to think as we’re talking years vs. decades not seconds vs. minutes. On methane, in practice I can’t see us going to zero even if we all went vegetarian. How would you feed the billions who rely on rice?

  53. Ben McMillan says:

    Crops for human food directly account for 21% of GHG emissions from the food sector. There is land-use on top of that (getting you to ~30%), and various supply chain emissions (probably energy-related and mostly CO2). So methane from crops is not the biggest problem.

    if you really wanted zero-methane agriculture, that would indeed be very hard. But just because perfection would be hard doesn’t mean we shouldn’t bother with massively better.

    Agriculture could have a really important role to play in environmental terms, not just in GHG emissions but e.g. in terms of local pollution and ecosystem services/habitat protection. The idea that excluding the agriculture sector from climate policy will help protect it appears misguided: farming could play a big role (and make a lot of cash) helping to be part of the climate solution.

  54. Ben,
    Indeed, I agree, I don’t think it should be excluded, for all the reasons you suggest. My only real point is that I think it’s worth being aware of the differences between long-lived GHGs like CO2 and short-lived GHGs like methane.

  55. Ben McMillan says:

    ATTP: yes, I don’t think I’m disagreeing with you, and I realise that this is somewhat orthogonal to the OP.

    By the way, this article is useful on agriculture emissions, and the tables in the supplementary data break it down by food item (e.g. rice accounts for 10% of food emissions by itself).

  56. Ben McMillan says:

    Also, I think the data suggests agricultural emissions of N2O and methane are actually about equal in CO2eq terms (and N2O is pretty long-lived).

    So reducing N20 emissions might be a good target. Associated fertilizer emissions are also pretty unpleasant as local pollution.

  57. Chubbs says:

    Think we are in general agreement. Whether we have chosen or not, It is better to focus on fossil CO2 vs Ag methane. However, we have procrastinated so long, that all sectors need to contribute. Methane is our ace-in-the-hole to balance warming from reduced aerosols as fossil fuel burning decreases.

  58. DG says: “On methane, in practice I can’t see us going to zero even if we all went vegetarian. How would you feed the billions who rely on rice?”

    I don’t know the answer to your question, Dave, but I think we should aim for net zero methane and I think there are ways to reduce methane emissions related to rice farming:

    I understand that some folks would like to keep things simple and maintain focus on one thing at a time, like CO2 emission reduction, and other stock emissions.

    We are leaving things rather late, but I guess the idea is that we can come back even later and work on the flow emissions issues. Historically, methane has been under 700 ppb and we haven’t even hit 1900 ppb yet, so yeah, let’s ignore the short term heat spikes associated with a flow pollutant like methane and tackle the big bear stock pollutants. I see the logic in that. It’s very orderly and organized. If we allow too much urgency to creep in to our considerations (I won’t use the P word) than we might attempt to whack all the moles at once.

    I think back on what I know about WWII and I think this is why the orderly way that the US geared up to take part in that sad affair is kind of the same. It was a good thing that we didn’t bother with cranking out military airplanes until we had the naval fleet re-established. And holding off on training ground troops and making munitions until we had sufficient means to airlift soldiers and ship munitions to combat and to start using munitions kept things simple and orderly. I look back and see how planes and ships are sort of like stocks and the soldiers were sort of like flow. Even on a war footing, it makes no sense to give in to the P word and attempt to do everything at once. It’s not an orderly way to proceed.



  59. Attp says “My only real point is that I think it’s worth being aware of the differences between long-lived GHGs like CO2 and short-lived GHGs like methane.”

    Methane historically has been under 700 ppb and we are creeping up toward 1900 ppb these days, so that’s moving up, but not too fast. If you chart it, it’s looks like a hockey stick, but so what? Methane is short lived in the atmosphere, we just need to keep an eye on it for now because it’s a flow pollutant.

    I am curious about what level of methane in the atmosphere should trigger an alarm. Is there a reasonable level for a short-lived global warming gas like methane where we need to switch from observing it to working to reduce its level in the atmosphere? Would that be 3000 ppb? or 30,000 ppb? At what level does the short-lived warming spike from methane overcome its insignificance as a flow pollutant? At that point the difference between methane and CO2 slips away. It’s a difference that makes no difference when we hit that point. It helps me to have a number in mind to know when that change happens.



  60. Chubbs says: “Methane is our ace-in-the-hole to balance warming from reduced aerosols as fossil fuel burning decreases.”
    That’s an interesting and optimistic idea. You are playing the long game there, Chubbs. Well done!

  61. MMM says:

    I agree with WMC. The GWP is meant to be a metric that is meant to approximate equivalent climate impacts of a pulse of emissions… but until the GWP* work, I’d never seen anyone claim that GWPs were meant to equalize temperature paths. The question the GWP answers is which is worse, emitting X tons of methane or Y tons of CO2? And I think it does it pretty well. If you look at the dark blue line for CO2, and the orange line for methane, I would have a hard time deciding which of those two worlds I’d want to be in: earlier warming with a higher peak, or more gradual warming but lasting longer. And that makes sense: several papers have used damage function approaches to determine the equivalent discount rate for each possible GWP timescale (see Mallapragada and Mignone, for example), and found that the 100 year timescale for the GWP is equivalent to a damage metric with a 3 percent discount rate. Value long term warming more? That implies a lower discount rate and a longer timescale.

    Meanwhile, the GWP* is not a practical substitute for the GWP in a number of scenarios: the requirement to know emissions history (rather than just comparing emission pulses in a single time period) makes it too complicated for every day use. Emission inventories for a single year? Trading regimes? And it has this counterintuitive nature where methane emissions can have a negative GWP*… even though emitting a ton of methane is always warming relative to not emitting a ton of methane. (yes, they’ve scale it so that emitting less methane means larger negative numbers, but… I’m sorry, that’s just going to confuse people).


  62. MMM,

    I agree with WMC. The GWP is meant to be a metric that is meant to approximate equivalent climate impacts of a pulse of emissions…

    Okay, but how does it do this? Technically, GWP is simply an integral of the radiative impact (as measured by a change in the planetary energy imbalance) over some time interval. Why can this then be used to determine the climate impact of some emission? The reason it is for CO2 is because of the roughly linear relationship between emissions and warming. This relation doesn’t hold for methane emissions.

    If you look at the dark blue line for CO2, and the orange line for methane, I would have a hard time deciding which of those two worlds I’d want to be in: earlier warming with a higher peak, or more gradual warming but lasting longer.

    Sure, but this isn’t what GWP would indicate. If you tried to do something like this with GWP you’d estimate that both CO2-eq emissions are equivalent (by definition) which they aren’t. I’m certainly not suggesting that it wouldn’t be quite reasonable to decide that you want to reduce methane emissions to reduce shorter term warming. I’m simply suggesting that it’s worth being aware of the different warming profiles of the different GHGs.

    Meanwhile, the GWP* is not a practical substitute for the GWP in a number of scenarios: the requirement to know emissions history (rather than just comparing emission pulses in a single time period) makes it too complicated for every day use.

    True, you do need to know some emission history, but that’s the nature of warming profile due to methane. We can certainly decide that it’s too complicated, but then you’re left with a metric that doesn’t do as good a job (IMO) of representing the impact of methane emissions.

    And it has this counterintuitive nature where methane emissions can have a negative GWP*… even though emitting a ton of methane is always warming relative to not emitting a ton of methane.

    True, but one could argue that this is fair. To limit future impacts of emissions, CO2 emitters need to get their emissions to zero. To limit the future impact of methane emissions, they don’t need to get emissions to zero and if they can get their emissions to go down, that has a net climate benefit. Maybe we shouldn’t recognise this, but I think it climatically correct.

  63. MMM says:

    “Technically, GWP is simply an integral of the radiative impact (as measured by a change in the planetary energy imbalance) over some time interval. Why can this then be used to determine the climate impact of some emission?”

    See Mallapragada & Mignone:

  64. MMM says:

    “Sure, but this isn’t what GWP would indicate. If you tried to do something like this with GWP you’d estimate that both CO2-eq emissions are equivalent (by definition) which they aren’t.”

    The GWP isn’t saying that the CO2-equivalent missions are IDENTICAL, we are saying they are EQUIVALENT. That’s the nature of a metric. It is basically the “net present value” of two choices. The integrated radiative forcing over 100 years turns out to map pretty well to the expected damages using a discount rate of 3 percent. So 100 year GWP equivalency is giving you damage equivalency, which is one way to make decisions.

  65. MMM,
    Thanks, I’ll have to look at that paper properly. However, isn’t an issue the following. If there is an emission of CO2 into the atmosphere, then this produces a change in forcing that then leads to warming and, consequently, impacts. If there is an emission of a CO2-eq amount of methane, then whether or not this produces a change in forcing, warming, and impacts depends on whether or not methane emissions have been increasing, are flat, or going down. It seems that the use of GWP does indeed imply an equivalence between methance emissions and CO2 emissions, but this equivalence may be wrong. It may be fine when methane emissions are going up, but becomes increasingly discrepant (AFAIA) if this is no longer the case.

  66. MMM says:

    “If there is an emission of a CO2-eq amount of methane, then whether or not this produces a change in forcing, warming, and impacts depends on whether or not methane emissions have been increasing, are flat, or going down.”

    This is this why I think the “negative emissions” issue confuses matters. You have some background scenario. In that scenario methane emissions could be going up, they could be going down, they could be standing on one leg and singing “When Father Painted the Parlor”*, it doesn’t matter: if you emit an additional ton of methane, that additional ton will lead to warming relative to a universe in which you didn’t emit it. The GWP makes that clear.

    *Arcadia by Tom Stoppard reference: I highly recommend reading it!

  67. MMM,
    Okay, but that still seems that the comparison between methane and CO2 isn’t consistent. In the case of CO2, you’re measuring the warming relative to the world at the time when it was emitted. For methane it seems that you’re measuring it relative to some world in which methane emissions had never happened (I think – I may be getting confused here, which could be illustrating your point 🙂 ).

  68. MMM says:

    ATTP: for the GWP, for either CO2 or CH4, the metric is showing a rough estimate of the warming effect of a pulse of emissions relative to the world in which the emissions didn’t happen.

    The GWP* is a good quick and dirty way to project temperatures for total emissions pathways when you don’t want to use reduced complexity models like FaIR or MAGICC. The GWP would never be used for projecting temperatures, but can be very useful for single-year inventories, trading protocols, or quick analysis of the relative climate impacts of two different sources or mitigation options.

    (and while I do think the GWP* is adding confusion to this area, it is also possible any confusion you have is resulting from my own lack of clarity!)

  69. MMM,
    But isn’t the problem that the damage estimate, or impacts, is relative to a world without further *warming* rather than relative to a world without further emissions? In other words, if we stopped emitting all CO2 we’d conclude that there would be no further impacts, but we’d be stuck with the damage/impacts from past emissions (which would essentially now be constant). However, if we stopped all emissions of methane, we’d actually reverse the impacts, or most of them, from past emissions. So, it still seems as though these estimates are assuming these gases have a similar behaviour when, in fact, they don’t. I would agree that this probably doesn’t matter that much when emissions are increasing, but might become more important as emissions start to reduce.

    Maybe this is a bit “cart before the horse” in that the first step would be to get emissions to stop going up for all gas species, and then we can worry about the differences between the different species once we’ve achieved that.

  70. Ben McMillan says:

    The more I think about the paper in the OP, the less I like it. They could have shown a curve for agricultural N2O+CO2+CH4 weighted together (instead of a pretty rainbow) and at that point their article would have looked like quibbling, because the agriculture emissions are not dominated by methane, and the curve wouldn’t be dramatically different from CO2.

    Also, they just talk about agriculture as a lump, but a lot of the emissions are associated with a few ‘bad apples’. A paper that was arguing for action rather than inaction would be interested in whether there is any low hanging fruit.

    I make beef+lamb about 25% of food emissions, but they are a tiny proportion of calories, or even protein. They aren’t even that big a proportion of meat: poultry and pork are each more popular than beef+lamb put together. A lot of these emissions are due to land use change, which is mostly not methane.

    That’s starting to add up to a decent slice of world emissions (maybe 5%, about equal to steel) for something that is pretty much entirely a luxury, and that most of the world consume very little of; the obvious substitutes are an order of magnitude better. Like aviation, even though it isn’t a big proportion of world emissions, it is a sizeable fraction for rich westerners (like the authors, who are from the UK+New Zealand).

    Even if you think methane is no big deal, that is still significant. Politically not easy in places like the US and Argentina though. There are other environmental+equity factors apart from GHGs but I think they mostly also point in the direction of reduced beef+lamb consumption…

  71. Ben,
    I think they would probably argue that you could do all that you suggest.

    A lot of these emissions are due to land use change, which is mostly not methane.

    Yes, but these emissions are typically already included in estimates of anthropogenic emissions. I don’t think the paper is suggesting ignoring these. It’s certainly the case that one aspect of emission reductions would be to reduce, or even, reverse land use change emissions, which would presumably also have an impact in agricultural methane emissions.

    Even if you think methane is no big deal, that is still significant.

    I certainly don’t think it’s no big deal, just that how it influences warming is somewhat different to the impact of CO2.

  72. attp says: “equivalence … may be fine when methane emissions are going up, but becomes increasingly discrepant (AFAIA) if this is no longer the case.”

    Methane has been a lot like CO2 in the industrial age, it has been an upward sticky number. I think the discrepancy potential if methane emissions stop rising looks like a footnote level matter.



  73. “Maybe this is a bit “cart before the horse” in that the first step would be to get emissions to stop going up for all gas species, and then we can worry about the differences between the different species once we’ve achieved that.”

    Amen, brother. Put the spurs to that thought. That dog barks for me.

  74. Ben McMillan says:

    I think they are calling into question at one point whether land use/energy use really ought to be be considered part of agricultural emissions, but since the paper isn’t really quantitative, it is a bit of a moot point.

    They did actually discuss meat briefly, which I missed, my bad.

  75. MMM says:

    ATTP: actually, there are some interesting interactions between what you assume about the future scenario and the relative value of reducing an additional ton of methane vs. CO2. Figure 2 in Mallapragada and Mignone shows that as future emissions are expected to be lower (RCP2.6 v. RCP8.5), the importance of methane mitigation increases (e.g., the equivalent GWP timescale decreases). This is consistent with Bowerman et al. (2013) which found that the value of reducing short-lived gases is higher when temperatures are expected to peak in the near term.

    One can think of the temperature/damage relationship having several attributes: peak temperature change, sustained temperature change, peak rate of temperature change, and near-term temperature change. In an RCP8.5 scenario, near-term SLCF reductions (rather than waiting to reduce them later) reduce near-term temperatures and near-term rate of change, but not peak temperature, sustained temperature, or peak rates. However, in an RCP2.6 scenario, near-term SLCF reductions reduce near-term temperatures, peak rate-of-change, and possibly peak temperatures (if it is a peak & decline situation).

    Bowerman, N. H., Frame, D. J., Huntingford, C., Lowe, J. A., Smith, S. M., and Allen, M. R.: The role of short-lived climate pollutants in meeting temperature goals, Nat. Clim. Change, 3, 1021–1024, 2013.

  76. MMM says:

    Also, not relevant to GWP v. GWP*, but relevant to relative value of CH4 and CO2 reductions: methane contributes to global background ozone levels with implications for human health, agriculture, and ecosystems. CO2 contributes to both ocean acidification and carbon fertilization (both good in terms of faster plant growth, and bad, because of stimulation of weeds and invasives and reductions in micronutrients and protein content as carbon to nitrogen ratios increase).

    In any case, I do think we should be making serious efforts to reduce both CO2 and CH4, and that the 100 year GWP is a decent approximation to the relative value of reductions of the marginal ton of either.

  77. Advancing Scientific Understanding of the Global Methane Budget in Support of the Paris Agreement
    “Plain Language Summary
    Methane is the second largest contributor to climate warming from human activities since preindustrial times. Reducing human‐made emissions by half is a major component of the 2015 Paris Agreement target to keep global temperature increases well below 2 °C. In parallel to the methane emission reductions pledged by individual nations, new capabilities are needed to determine independently whether these reductions are actually occurring and whether methane concentrations in the atmosphere are changing for reasons that are clearly understood. At present significant challenges limit the ability of scientists to identify the mechanisms causing changes in atmospheric methane. This study reviews current and emerging tools in methane science and proposes major advances needed in the coming decade to achieve this crucial capability. We recommend further developing the models that simulate the processes behind methane emissions, improving atmospheric measurements of methane and its major carbon and hydrogen isotopes, and advancing abilities to infer the rates of methane being emitted and removed from the atmosphere from these measurements. The improvements described here will play a major role in assessing emissions commitments as more cities, states, and countries report methane emission inventories and commit to specific emission reduction targets.”

    Revised records of atmospheric trace gases CO2, CH4, N2O, and δ13C-CO2 over the last 2000 years from Law Dome, Antarctica

    New technique for high-precision, simultaneous measurements of CH4, N2O and CO2 concentrations; isotopic and elemental ratios of N2, O2 and Ar; and total air content in ice cores by wet extraction

    There are other references …
    which give one a better understanding about the global methane and N2O budgets, for example.

    I remain skeptical of our bookkeeping attempts and/or reductions of CH4 emissions until we have a much better understanding of the global methane budget itself. The easiest thing for humanity to do is to fool itself using faux bookkeeping techniques.

  78. MMM,
    The point about the different RCPs is a good one. I think that might have also been pointed out in this paper (there is some overlap in the authors of the paper that this post is about and Bowerman et al.). I do agree that if what we might do along an RCP8.5-like pathway might be different to what we might do along a RCP2.6-like pathway. Maybe more realistically, what we might focus on initially while emissions are still climbing might be different to what we might focus on once they start dropping.

  79. Actually, the Bowerman et al. paper seems to be making a similar point to the point being made in the paper being discussed in the post

    Although this literature acknowledges that action on long-lived climate pollutants (LLCPs) such as CO2 is also required, it is not always appreciated that SLCP emissions in any given decade only have a significant impact on peak temperature under circumstances in which CO2 emissions are falling. Immediate action on SLCPs might potentially ‘buy time’ for adaptation by reducing near-term warming; however early SLCP reductions, compared with reductions in a future decade, do not buy time to delay reductions in CO2.

  80. Ben McMillan says:

    Bowerman et. al. indeed makes a clean argument that dealing with short-lived forcings becomes pretty important a couple of decades before the peak of the warming curve.

    This suggests that you do ideally want methane emissions to get to near-zero about the same time as long-lived forcings like CO2, and actually somewhat earlier. Hard to see how you could do that unless you start trying now (assuming a 2C or 1.5C type approach).

    I don’t think that fits that well with the arguments in Lynch et. al. (although they aren’t very definitive about anything).

  81. Ben,
    I think the general argument is similar. Making early cuts to methane doesn’t really buy you time. If you want to limit warming, then you need to get CO2 emissions to go down and then reductions in methane emissions become increasingly important.

  82. David B Benson says:

    If vegetable-based artificial meat tastes as good as the meat provided by rumnants, principally cattle, and is less expensive then the market will largely eliminate the major source of methane from agriculture.

  83. David B Benson, I don’t have the numbers at hand but last time I eyeballed methane emissions it seemed that rice paddies were a larger source than livestock. Worth looking at, anyhow.

  84. “last time I eyeballed methane emissions it seemed that rice paddies were a larger source than livestock. Worth looking at, anyhow.”

    A few points on these q

  85. questions:
    1. Higher yields and lower methane emissions with new rice cultivars
    2. A culture/society that was committed to net zero emissions would likely decide that livestock raised primarily for meat as a large chunk of the food system is not very compatible with the net zero status, so comparison of rice paddie emissions to livestock emissions is a bit of a non-starter. Our net zero goal likely requires signicant changes to both of these foodstuff classes, so probably not worth looking at, we have to slam the emissions from both of these sources
    3. I think we really need to stop thinking of either/or options and start thinking of both/and or “all of the above.” The either or thinking just complicates thing imo. I think we are capable of doing several things at the same time. I have seen people walk and chew gum, so this is not theoretical.

    I see this either/or distraction arising again and again in ways that slow our attempt to get to net zero. I see it in the original post where there is an implication that we can’t work to simultaneously greatly reduce both methane and CO2 at the same time because one is a flow and the other is a stock. And hey, if we can do two things at once, how about three? It is certain that CO2 is the big dog that is biting us on the ass, but methane is still a mean little critter that can make our lives harder. And, as someone mentioned earlier, nitrous oxide should not be overlooked because it breaks down slowly in the atmosphere and it also warms the globe.

    Why not approach this like the public health emergency that it is and commit to reducing all the greenhouse gases as fast as we can?

    To press this point of view is simple logic and common sense. I believe that Buckminster Fuller was right when he said that we can afford to do anything that we have to do. What we have to do is greatly reduce all greenhouse gas emissions as quickly as we can now because we have left things a little late as Ken noted earlier.


  86. Ben McMillan says:

    ATTP: Well, I can see reasons that urgent action on methane might be of secondary importance, especially if, as Bowerman says, you don’t know if humans will do anything about CO2 any time soon.

    But we’re now pretty much committed to a “methane later” strategy anyway given how long change takes, so this is all a bit moot anyway.

  87. Ben McMillan says:

    This paper (in supplementary data ‘Data S2’) has a useful spreadsheet for food emissions:

    I guess for me, the interesting thing is that different meats have such different associated emissions, which suggests a simple option, not beef-vs-rice (which is just “but China”).

  88. Ben,

    But we’re now pretty much committed to a “methane later” strategy anyway given how long change takes, so this is all a bit moot anyway.

    Yes, this is probably (sadly) the case.

    I guess for me, the interesting thing is that different meats have such different associated emissions, which suggests a simple option, not beef-vs-rice (which is just “but China”).

    Yes, we could reduce methane emissions by eating less of the meat that is associated with high levels of methane emissions (beef, for example).

  89. Willard says:

    There seems to be a connection between agricultural choices and “but growth.” A Climateball player who would insist in increasing GDP and reducing GHGs needs to follow through the nutritional implications:


    • Country of origin accounted for a large share of the variation among diet footprints.
    • Reducing animal foods in general was more climate-friendly than eliminating meat.
    • Eating low on the food chain was comparable to vegan for GHG and water footprints.
    • Pond-raised aquatic animals were by far the most blue water-intensive foods.
    • Meeting both sustainability and health goals required more ambitious dietary shifts.

    There are ethical arguments for eating bivalves, as these species might suffer less from captivity.

  90. Ran across this article about Canadian agriculture and global warming.

    “Scientists with the National Oceanic and Atmospheric Administration in the U.S. recently found 2020 was earth’s second-hottest year on record, with the average land and ocean surface temperature across the globe at 0.98 of a degree C above the 20th-century average.

    However, the agency found the northern hemisphere saw its hottest year on record, at 1.28 degrees C above the average.

    “(In Canada) we are looking at about 6.4C degrees of warming this century, which isn’t much less than one degree per decade, which is just a terrifying rate of warming,” Darrin Qualman, the director of climate crisis policy and action at the National Farmer’s Union said.”

    The article did not distinguish in a meaningful way as to how much of this warming might be attributed to stock v. flow pollutants.


  91. Ben McMillan says:

    Willard’s link was interesting, really shows the climate impact of beef+dairy. Their land-use change figures for beef are so much lower than in the paper I was quoting (because presumably these estimates are hard and very methodology-dependent).

    Raw land use (rather than change) due to animal products seems relevant too; land previously used for grazing/feed crops is where Shell will have to grow its forest the size of Brazil.

  92. Chubbs says:

    Yes, Willard’s link was interesting. This has been a good discussion. Methane will disappear quickly, still agriculture has a lot on its plate. Has to feed 8B people sustainably, as the climate changes and water resources deplete.

  93. Hey, Chubbs. I don’t think it makes sense to talk about what “agriculture” has on its plate. There is no there there. It’s like saying that energy has to stop emitting so much greenhouse gas. The decision-making and responsibilities rest with us, (humans/consumers) not with the large societal structures.

    Agriculture does not have to feed 8B people sustainably as climate changes and resources are depleted. That sustainable feeding task is simply not mandated and may or may not be possible given climate change and resource depletion.

    We (humans/consumers) may want to feed 8B people sustainably. We need to talk seriously about how such a thing might be done. Our current food system consumes a lot of petro chemicals to produce foodstuffs. We are essentially eating oil.


    I am interested in ideas about how humans might develop a sustainable food system, about what that would look like and how many people such a system might feed.

    My spouse and I have been watching this series:
    It may be helpful to realize that civilization collapse has happened frequently in the past as this series spells out. Collapse of civilizations is easily confused with end times craziness of revelations in the Bible, but it’s not the same thing at all in my opinion.



  94. “I am interested in ideas about how humans might develop a sustainable food system, about what that would look like and how many people such a system might feed.”

  95. David B Benson says:

    smallbluemike — In Edo Japan, about 80% or more were peasants. In the USA at the time of the Constitutional Convention, about 20 farmers to 1 doing something else, I was told.

    So sustainable agriculture requires most people are doing that, I opine.

  96. Willard says:

    Searching to substantiate Ben’s “Shell will have to grow its forest the size of Brazil,” I found this:

    In a blog post accompanying the scenario’s release, Shell’s chief climate adviser David Hone says the path is “all about managing emissions, so coal drops out very early, CCS emerges rapidly and land is managed with conservation and carbon in mind”.

    However, many of the key moments identified in the report – peak coal already passed, peak oil in 2025, peak fossil gas in the mid-2030s – are familiar, given they already appeared in Shell’s previous Sky scenario.

    In fact, a comparison by Carbon Brief of the energy pathways identified in both scenarios shows that, apart from accounting for the Covid-related dip in the early 2020s, they are essentially the same.


    Although data on land-based emissions was not formally included in the previous Sky scenario, the idea is not actually new.

    Work commissioned by Shell from the Massachusetts Institute of Technology (MIT) Joint Program on the Science and Policy of Global Change for the 2018 scenario found that “an area the size of Brazil being reforested offers the possibility of limiting warming to 1.5C”.

    The Brazil comparison has also been used by Van Beurden, who told an industry conference in 2018: “It’s not what some people sometimes think: we’ll just do a little bit more solar, a bit more wind and we’ll get there.”

    The interactive charts are interesting. The main difference between the 1.5C and the 2C scenario are trees. Brazil is 8,5 million square kilometers. According to an online calculator, that amounts to one billion and a half (or 1,591,414,286) proverbial football fields.

    Perhaps we ought to consider other kinds of plants than trees.

  97. Willard says:


    I think drive-bys (say “But CAGW”) would make more sense when they don’t challenge or call out other commenters. That’s how we usually get food fights. One drive-by per thread is usually fine. If the policy is gamed it might be revised.


    Also, WordPress now embeds PDFs when a URL ending with “pdf” is added in your comments. To bypass the embedding, add something in front of the URL, e.g. “source.”


  98. In a thread sort of about food sources, no less, we, of course, get into … food fights. 😉

  99. If Ben is referring to BECCS, then my understanding is that the land requirements are quite extreme. I recall some estimates that suggested you’d need a large area comparable, or larger than, the size of India. Not quite sure how that compares to Brazil 🙂

  100. Here’s the paper I was thinking of

    Under the IPCC SR1.5 P4 overshoot scenario, the area of bioenergy crops required by BECCS, 7.2m km2, is nearly two and a half times the size of India, for cumulative removals of 1,191 GtCO2 to 2100.

  101. Willard says:

    > Not quite sure how that compares to Brazil

    We’d need cricket fields to estimate that properly.

    India is 3,287 million km², so 812,235,389 acres. A cricket field is around 4 acres. So that would be something like 203 million cricket fields.

    If someone could double-check the numbers, that’d be great.

  102. Ben McMillan says:

    Yes, exactly, I was thinking of that carbonbrief report; the weird thing is that the standard 1.5C scenarios (not just those coming out of Shell) have pretty ginormous negative emissions technology deployment. Often of the burn-the-trees-and-bury-the-CO2 variety (BECCS).

    And that requires a lot of land to grow crops (possibly trees), which isn’t compatible with lots more grazing animals. Perhaps we’ll need to use the oceans as well:

    The problem is that we are pushing all the planetary boundaries at the same time.

  103. [Playing the ref. -W]

  104. mrkenfabian says:

    Smallbluemike said – “The decision-making and responsibilities rest with us, (humans/consumers) not with the large societal structures.”

    I disagree. We may all bear a share of responsibility but some shareholders – the institutional ones especially – do bear more responsible than the ordinary citizen (or subject).

    Decision making by energy companies wrt their future investment choices trumps consumer level choice in this – I think, their choice creates the necessary consumer level options that allow lower emissions choices by consumers. And low emissions options at the energy generation/energy company level are now available and cost effective choices. I don’t think they should be entirely ‘free’ choices unless and until there is carbon pricing to start including externalised costs that are currently counted as ‘free’. Even then energy supply is too critical to be outside the scope of good governance to interfere.

    Decisions at government policy level have strong influence over the direction energy company investments go.

    Choosing to reduce personal emissions is laudable but limiting emissions reductions requirements to consumer level and further, limiting it to those who care enough to want to choose them, can never be sufficient. Until all energy choices are low emissions ones – and everything made and consumed has low embodied emissions, up to and including extravagantly wealthy and wasteful choices – we will not have fixed the problem. And I am NOT going to advocate for elimination of wealth and wasteful consumption; there is enough misrepresentation of climate activism as driven by socialist/globalist/environmentalist/scientist-ist extremism already.

    Handing the issue and the microphone to those that are extremists – then mocking and deriding them (lumping everyone with climate concerns in with them) – has not made the extremists responsible for our choices and our direction; it was an abrogation of responsibility by people in positions of high trust, who should and almost certainly did know better, and THEY chose. Time they chose again I think.

  105. Sorry, Ken. I was unclear. I agree with you that emissions cannot/should not be controlled entirely from the demand side. Reducing your personal demand is laudable as you note. My point was about how it is up to humans to demand reductions, then to be actively engaged in the decisions about how the reduction plan is designed. I favor carbon fee and dividend as a reduction plan.

    Came across this today from a friend who runs a family farm:

    From that piece (in which Biden is aspirational): “The president predicted that the United States would be the “first in the world” to achieve net-zero emissions from its ag sector, which currently accounts for an estimated tenth of total US emissions. And former and future Agriculture Secretary Tom Vilsack declared agriculture “the first and best place to begin getting some wins” on climate.

    But where, exactly, does the new administration believe those victories will come from? The available evidence points to one place in particular, a new “carbon bank” that would pay farmers, foresters and ranchers to store carbon in their soil through regenerative agriculture and other climate-friendly techniques. The plan aims to turn vast swaths of America into massive carbon sinks, helping to partially offset the nearly 7,000 megatons of greenhouse gases the US emits each year.”

    If we were to wait for a nebulous entity that we might call “agriculture” to bring forth these ideas, I think we would be waiting for a long, long time. Big agriculture is a corporate enterprise that is bound to shareholder profits as an outcome that is much more important than carbon sequestration. We would probably see big ag get interested in carbon sequestration if there was a payoff to the business and shareholders, but that depends on human beings exerting political pressure to change the economic landscape in which big ag exists. Big Ag, like Big Oil, is not going to redesign their commodities marketing scheme on their own. Why would they? It’s risky and it could fail to be profitable and/or create stranded assets on the books.

    A small family farm that has been established on the premise of creating a sustainable/local low or even net zero emission food system is not big ag. These two agricultural systems have very little overlap in a venn diagram with the exception being production of foodstuff for sale.



  106. Ben McMillan says:

    Those kinds of incentive mechanisms are exactly the kind of thing that ‘big ag’ loves and lobbies for: after all, they were the ones behind the rush for biofuels/ethanol for ‘environmental reasons’.

    The hard bit is designing the incentives so they actually have a positive impact on the environment, rather than just ending up optimising one thing, but making almost everything else worse.

    What you might want is essentially people to do less agriculture, and more things that look more like piecemeal stewardship, and then things get tricky. Lots of people with the wrong skills and stranded assets. Needs a lot of top-down micromanagement, rather than a economist-style universal taxation scheme.

    People that really love the idea of a more local and artisanal agriculture sector will join local farming collectives and so on, but I don’t think the movement can come all from that end; most of the land and food and employment is still tied to the big concerns and that won’t change fast.


    ➔ Updates for many countries have made it possible to estimate hunger in the world with greater accuracy this year. In particular, newly accessible data enabled the revision of the entire series of annual undernourishment estimates for China back to 2000, resulting in a substantial downward shift of the series of the number of undernourished in the world. Nevertheless, the revision confirms the trend reported in past editions: the number of people affected by hunger globally has been slowly on the rise since 2014.

    ➔ Current estimates are that nearly 690 million people are hungry, or 8.9 percent of the world population – up by 10 million people in one year and by nearly 60 million in five years. The number of people affected by severe food insecurity, which is another measure that approximates hunger, shows a similar upward trend. In 2019, close to 750 million – or nearly one in ten people in the world – were exposed to severe levels of food insecurity.

    ➔ Considering the total affected by moderate or severe food insecurity, an estimated 2 billion people in the world did not have regular access to safe, nutritious and sufficient food in 2019.

    ➔ The world is not on track to achieve Zero Hunger by 2030. If recent trends continue, the number of people affected by hunger would surpass 840 million by 2030.

    ➔ A preliminary assessment suggests that the COVID-19 pandemic may add between 83 and 132 million people to the total number of undernourished in the world in 2020 depending on the economic growth scenario.

    ➔ Globally, the burden of malnutrition in all its forms remains a challenge. According to current estimates, in 2019, 21.3 percent (144.0 million) of children under 5 years of age were stunted, 6.9 percent (47.0 million) wasted and 5.6 percent (38.3 million) overweight.

    ➔ The world is making progress but is not on track to achieve the 2025 and 2030 targets for child stunting and low birthweight, and for exclusive breastfeeding, is on track only for the 2025 target. The prevalence of wasting is notably above the targets. Most regions are not on track to achieve the targets for child overweight. Adult obesity is on the rise in all regions. Urgent action is needed to reverse these upward trends.

    ➔ The nutritional status of the most vulnerable population groups is likely to deteriorate further due to the health and socio-economic impacts of COVID-19.

    ➔ Food insecurity can worsen diet quality and consequently increase the risk of various forms of malnutrition, potentially leading to undernutrition as well as overweight and obesity.

    ➔ Low-income countries rely more on staple foods and less on fruits and vegetables and animal source foods than high-income countries. Only in Asia, and globally in upper-middle-income countries, are there enough fruits and vegetables available for human consumption to be able to meet the FAO/WHO recommendation of consuming a minimum of 400 g/person/day.

    ➔ While we still face significant challenges in just accessing food, challenges are even more important in terms of accessing healthy diets.

    ➔ Healthy diets are unaffordable to many people, especially the poor, in every region of the world. The most conservative estimate shows they are unaffordable for more than 3 billion people in the world. Healthy diets are estimated to be, on average, five times more expensive than diets that meet only dietary energy needs through a starchy staple.

    ➔ The cost of a healthy diet exceeds the international poverty line (established at USD 1.90 purchasing power parity (PPP) per person per day), making it unaffordable for the poor. The cost also exceeds average food expenditures in most countries in the Global South: around 57 percent or more of the population cannot afford a healthy diet throughout sub-Saharan Africa and Southern Asia.

    ➔ All diets have hidden costs, which must be understood to identify trade-offs and synergies in relation to other SDGs. Two hidden costs that are most critical relate to the health (SDG 3) and climate-related (SDG 13) consequences of our dietary choices and the food systems that support these.

    ➔ Under current food consumption patterns, diet-related health costs linked to mortality and non-communicable diseases are projected to exceed USD 1.3 trillion per year by 2030. On the other hand, the diet-related social cost of greenhouse gas emissions associated with current dietary patterns is estimated to be more than USD 1.7 trillion per year by 2030.

    ➔ Shifting to healthy diets can contribute to reducing health and climate-change costs by 2030, because the hidden costs of these healthy diets are lower compared to those of current consumption patterns. The adoption of healthy diets is projected to lead to a reduction of up to 97 percent in direct and indirect health costs and 41–74 percent in the social cost of GHG emissions in 2030.

    ➔ However, not all healthy diets are sustainable and not all diets designed for sustainability are always healthy. This important nuance is not well understood and is missing from ongoing discussions and debates on the potential contribution of healthy diets to environmental sustainability.

    ➔ To increase the affordability of healthy diets, the cost of nutritious foods must come down. The cost drivers of these diets are seen throughout the food supply chain, within the food environment, and in the political economy that shapes trade, public expenditure and investment policies. Tackling these cost drivers will require large transformations in food systems with no one-size-fits-all solution and different trade-offs and synergies for countries.

    ➔ Countries will need a rebalancing of agricultural policies and incentives towards more nutrition-sensitive investment and policy actions all along the food supply chain to reduce food losses and enhance efficiencies at all stages. Nutrition-sensitive social protection policies will also be central for them to increase the purchasing power and affordability of healthy diets of the most vulnerable populations. Policies that more generally foster behavioural change towards healthy diets will also be needed.

    ➔ I am sort of thinking that I know next to nothing about food security, with or without climate change. That this thread is just filled with rather ironic comments wrt agriculture. And that I would rather get out there and do something about agriculture than to just talk about doing something about agriculture, but that I am more likely to do nothing wrt agriculture. File that one under … but nothing.

  108. izen says:

    Let them eat cake…

  109. Willard says:

    > I would rather get out there and do something about agriculture than to just talk about doing something about agriculture, but that I am more likely to do nothing wrt agriculture.

    That tu quoque can be turned on its head: to ironize about commenters is still doing something, for it’s one thing one might do with words. It can also defused by making its false dilemma explicit. Walking and talking are far from being incompatible. Same as walking and chewing plastic bits.

    As KenF underlines, we need to distinguish the types of actors involved. Hippies (be they organic freaks or hipsters) should not be conflated with big AG. Responsibilities ain’t the same. And for what it’s worth the hippies’ track record is far from being bad: the beer market changed, we have cheese that taste something in America, Fair-Trade is making a difference, plant-based diets are now mainstream, etc.

    Speaking of talking the walk, Sarah told me in December that she wrote a first draft for her book. She won’t be portraying the American Big AG as some kind of well-optimized machine. So even in industrialist terms there is room for improvement.

  110. Ben McMillan says:

    Ethanol production now uses about 30% of US corn output. Certainly wouldn’t want to give emissions from that a free pass. For one thing, they are mostly not methane; also, if it actually increases emissions, the exercise is a bit pointless (except for transferring some cash around).

  111. Joshua says:

    Off topic –

    Hey Willard –

    I wanted to send you a link but I couldn’t find any past Twitter correspondence. Then when I clicked on you here I saw you got the boot? Huh? And it’s weird how all past correspondence is just completely disappeared? I didn’t realize that’s what happens. What a bizarre phenomenon Twitter is. Space/time distorting. Personas are created and destroyed. Thi fs that once existed do no longer. It’s like another dimension in the multiverse.

    Anyway, here’s the link. I thought you might be interested.

  112. Willard says:


    All it takes is a clownish tweet that looks remotely like a threat. I appealed, but got rejected with a canned response. It’s standard policy. Now the matter is into the hands of the Better Business Bureau. A similar incident happened to Cathryn Townsend last summer. It took a month to get sorted out. My case might be different from hers. For starters Willard is a ninja.

    Even if I eventually get my account back, I won’t tweet as much. In fact, I’ll make sure anything I do is independent from any platform I do not control. Most of my interventions were made in the spirit of helping the Climateball community. What sucks above all is missing the friends I made along the way.

    All of my chats for my **We Are Science** series were made via DMs. Many of my tweets contain research. Many comments I made here link to my tweets. Twitter is causing me harm, but less than I thought at first. There are so many other ways to fight contrarian crap than teh Twitter, and other ways to reach people, the first of them being my longtime friends.

    So I can’t say my life has suffered much from losing the right to tweet. (They also banned the Climateball account, and in fact conflate the concept of user and the concept of account.) I don’t lack projects, I sleep more, and I gained in focus. In retrospect, the “do I have any notification” signal creates an addictive cycle that isn’t good for attention.

    I heard recently this Radiolab episode on how and why Facebook has now a board that looks like an independent Supreme Court:

    Since its inception, the perennial thorn in Facebook’s side has been content moderation. That is, deciding what you and I are allowed to post on the site and what we’re not. Missteps by Facebook in this area have fueled everything from a genocide in Myanmar to viral disinformation surrounding politics and the coronavirus. However, just this past year, conceding their failings, Facebook shifted its approach. They erected an independent body of twenty jurors that will make the final call on many of Facebook’s thorniest decisions. This body has been called: Facebook’s Supreme Court.

    In any event, social platforms are light-years away from the policies AT designed for this website. He’s a good host.

  113. It’s too bad that it is easy to be banned or censored when you are misunderstood by the folks who have power over posts within any given platform, but it happens. There is seldom any meaningful recourse. Best to simply shrug it off and get on with your life.

  114. Willard says:

    Dear Mike,

    Passive aggression is boring after a few years, don’t you think?

    You’re not banned. Get over yourself.

  115. It’s not a great idea to always think the worst of people, Willard.

  116. Joshua says:

    Willard –

    > Twitter is causing me harm, but less than I thought at first.

    If I might overstep what’s proper, and while I can emphasize that it sucks, as someone who’s on record as laughing at right-wingers’ complaint about “censorship” (I’m not suggesting that’s what you’re doing) I’d suggest it’s good fodder (and more time) for meditation – as you alluded to.

    Have you seen this stuff?

  117. Joshua says:

    As if on cue….

  118. David B Benson says:

    Can we now return to the topic?

  119. Willard says:

    You don’t know what I think of people, Mike, but if that may console you I did consider removing Joshua’s comment and responding directly to him.

    You know why? Because every single time a topic however remotely related to moderation is mentioned someone will take the opportunity to play the ref. That’s gonna happen whether that commenter shrugged off moderation or not.

    Being banned from Twitter without justification is not moderation, but a Kafka trap. If you want to know why I moderate your comments, you can contact me by email.

  120. Brandon Gates says:


    I am saddened to hear you were b& from teh Tweeter; it angers me afresh that it is almost certainly tattle-tales by bad actors more deserving the hammer which got you tossed. Like you I was most hurt by losing contact with good friends and the destruction of DMs and Tweets containing unique content I valued. Fortunately I was able to maintain contact with some friends via other means.

    These days my main hobby is keeping ducks and chickens for eggs and meat. They are terrible ClimateBall players, which suits me just fine.

  121. izen says:

    “luvme some cancel culture”

    This the last gasp of an old-fashioned authoritarian government against the new techno-feudalism of the big social media companies.

    When private companies establish virtual monopolies over a social network it is inevitable that government will try and control what they publish. In the short term this can lead to the break-up of the monopoly with other players stepping in. But ultimately the efficiency and advantages of a single social network usually prevail.

    Of more interest is the situation in Australia where the government has been co-opted into the battle between the new social media and the old.

    Meanwhile the individual is of interest to these companies only as a source of money. There is no protection for personal expression beyond its financial advantage for the business. Government regulations on ‘free speech’ do not apply. Even if they did, they are superseded by ‘threats’ to national security.

    The original vision of the internet as a free marketplace (!) of ideas is succumbing to the dominance of big business and authoritarian governance.

    It is best to regard any electronic media as a temporary niche which you occupy at the discretion of the business and political will of much larger forces which can remove it at any time. The political and business ideal is of mass consumption of a small elite of ‘content providers’. Anything other than this is likely to be subject to arbitrary control either by big business and/or governance.

  122. Ben McMillan says:

    How do we feed everyone and replant forests?

  123. Steven Mosher says:

    temporary niche which you occupy at the discretion of the business and political will of much larger forces which can remove it at any time.

    thats why any digital asset of value belongs on a blockchain

  124. Steven Mosher says:

    How do we feed everyone and replant forests?
    and keep grids from failing


  125. Willard says:

    If only blockchains could feed everyone and replant forests.

  126. David B Benson says:

    Planners ought count on methane from dairy cattle and also from rice production as remaining steady into the indefinite future.

  127. Andrew J Van Wagner says:

    ATTP, I unfortunately didn’t get a reply from Stuart Ritchie or from Anti-Virus. I have officially terminated my effort to get answers from the questions from anti-lockdowners that I wanted to get answered by the Anti-Virus website. Why? Because at the point, there are diminishing returns to it as vaccination increases more and more and we approach the time when lockdown-measures will be terminated anyway. I don’t blame specialists for being busy during this crisis, and I can’t say for sure that answering my questions on a public website would’ve actually moved the needle with anti-lockdowners, but it is what it is.

    I saw this comment on Reddit:

    [But PSYOP. – W]

    I know a person who has sentiments like this, and I wonder if you could make an “Anti-Virus Discussion Thread” on ATTP that my friend could jump into and engage with you guys in. I think that he could be easily deconverted by reason/facts/evidence, though I don’t know if you guys on here are specialized enough to answer all of his questions.

    It would mean a lot to me if you guys could help me out with this.

  128. Andrew J Van Wagner says:

    *to get answers FOR the questions from anti-lockdowners that I wanted to get answered by the Anti-Virus website

  129. Andrew J Van Wagner says:

    ATTP, I realize that there was a discussion on “Anti-Virus” already, but that thread is closed now and I can’t post on it anymore.

  130. Steven Mosher says:

    Planners ought count on methane from dairy cattle and also from rice production as remaining steady into the indefinite future.

    but then politicians dont get to make decisions about who eats what when and where. and just when they got a years taste of micro managing the masses

  131. Ben McMillan says:

    If you include the opportunity costs of use of land for agriculture, and not just ‘land use change’ in expanding sectors, land-use-related CO2 emissions from agriculture are very large:

    e.g., if the land wasn’t being used for grazing, it might have a forest on it.

    Another thing they look at is biofuels:

  132. Andrew,
    I’ll see, but I have enough trouble moderating this site without threads that are likely to be contentious.

    Yes, that is a valid argument. Reducing lsnd use for agriculture could allow for changes that would act to sequester carbon.

  133. Andrew J Van Wagner says:

    ATTP, I would be extraordinarily grateful if you could at least give it a chance. My friend will be excruciatingly polite, courteous, respectful. I promise that I will tell him the rules regarding politeness, courteousness, and respect. In fact, my friend is extremely polite (I’m the one who has trouble being polite sometimes, but my friend stays polite at all times).

    If anything starts to go downhill then I 100% promise that my friend will 100% understand that you reserve the right to shut down the thread at the slightest hint of incivility or disrespect or heatedness.

  134. Ben McMillan says:

    I guess I would be happy enough if agriculture was exempt from carbon emissions requirements, but regulation emphasised things like local pollution, ecosystem services and biodiversity. You would lose an opportunity on the climate front, but arguably that might not be the priority.

    But at the moment there are huge incentives for things like biofuels, so the sector is up to their wellies in carbon-related regulation. i.e. the currently-existing problem is not excessive regulation on methane, but that agricultural emissions are unregulated, while their products are subsidised on the basis of being carbon-neutral.

    i.e. there is a lot of stuff going on like in the discussion with Sarah, where the system is set up for the benefit of land-owners, and little to do with jobs/making food ‘affordable’ etc. Especially in the UK, you get the feeling that countryside land-ownership and use is only incidentally related to food production. e.g., the vast hunting estates, which seem to be optimised for a certain type of costume play.

    This makes a lot of the chin-scratching about how agriculture needs special treatment and kid gloves on emissions seem a bit disingenuous.

  135. Chubbs says:

    It took decades of support to make solar and wind viable at scale. Agriculture is complex, with many strong vested interests, and as Ben points out very good at directing government policy to its own benefit. Sustainable commercial solutions in agriculture will probably take longer to develop and deploy than fossil fuels.

    Instead of methane emission reductions, I would focus on policy frameworks that encourage the deployment of better practices. Research by itself is a slow process; but as solar and wind show, commercial deployment at scale can be effective at driving down costs.

  136. Andrew,
    I don’t think the anti-virus comments have been closed. Your friend is welcome to comment. Just maybe suggest that they check the moderation and comment policies. These are never intended to be personal, they’re just intended to set down some groundrules.

  137. Ben,
    Yes, the whole issue of agriculture is pretty complicated and I am aware that it can be quite contentious. I saw a heated discussion on Twitter yesterday because someone had been highlighting how stable methane emissions wouldn’t lead to warming but that this had apparently been interpreted by farmers as meaning that stable herd sizes meant no future warming. However, there had apparently been changes to the make up of the livestock (dairy versus meat) which meant that even though the herd sizes had been constant, methane emissions had not. So, it is tricky to make sure that the message is clear and consistent and not then used in ways that can misrepresent what is happening.

    Your comment reminded me that I listened to this webinar with Rachel Mason who was an astronomer in a tenured position (who, I discovered, had done their PhD where I now work) but has now shifted into sustainability work after doing a Masters. I found it very interesting and I think it did highlight some of what was being discussed in that discussion with Sarah

  138. Willard says:

    Beautiful page, depressing reality:

    Water is declining around the world. Today, fresh water reserves are shared among more people than ever before, each consuming an increasing amount of water in their daily lives. Climate change is melting glaciers and intensive farming is depleting underground resources in some of the most populated areas of the world.

  139. Steven Mosher says:

    [Funny, still playing the ref. – W]

  140. Ben McMillan says:

    ATTP: it is indeed a pretty tangled and emotive issue. For example, the pushback along the lines of, X is just as bad as beef/dairy, so why should I give it up when some other person is doing X.

    I’m just going to note again that agriculture, and grazing animals in particular, also involves quite a lot of N2O, so it is not just methane (and considerable amounts of CO2, depending on how you do the accounting).

  141. D’oh! …

    Global human-induced emissions, which are dominated by nitrogen additions to croplands, increased by 30% over the past four decades to 7.3 (4.2–11.4) teragrams of nitrogen per year. This
    increase was mainly responsible for the growth in the atmospheric burden. Our fndings point to growing N2O emissions in emerging economies—particularly Brazil, China and India.

    A comprehensive quantification of global nitrous oxide sources and sinks
    (oaywalled but you know where to find a digital copy. at your local technical library or some such)

    It is not like I done did learned non-point source pollutants (urban through to rural) like 45 years ago, oh wait, I did.

    Croplands! :/

  142. Ben McMillan says:

    EFS: their table seems to give 2.3 teragrams of nitrogen per year from ‘direct soil emissions’ and 1.5 teragrams from ‘manure’. Any manure used to fertilise crops is counted in the former.

    I’m trying to figure out what your point is… obviously the ag N2O emissions are almost entirely manure+synthetic fertiliser, which is mostly on crops (but non-crop emissions is a significant minority). Some fraction of those crops feed humans, some feeds other animals and some is used for biofuel.

    I guess the ‘which places are most to blame’ think is a bit problematic in that it doesn’t usually go towards solutions. ‘What diet should I choose’ or ‘how does one grow these crops with lower emissions’ seems like more productive questions…

  143. Ben McMillan.

    “Nitrogen fertilizers
    Nitrogen fertilizers are made from ammonia (NH3) produced by the Haber-Bosch process.[16] In this energy-intensive process, natural gas (CH4) usually supplies the hydrogen, and the nitrogen (N2) is derived from the air. This ammonia is used as a feedstock for all other nitrogen fertilizers, such as anhydrous ammonium nitrate (NH4NO3) and urea (CO(NH2)2).

    Deposits of sodium nitrate (NaNO3) (Chilean saltpeter) are also found in the Atacama desert in Chile and was one of the original (1830) nitrogen-rich fertilizers used.[25] It is still mined for fertilizer.[26] Nitrates are also produced from ammonia by the Ostwald process.”

    But maybe you are thinking about manure spreaders (say those two words with a Vermont country accent like Ronald Kennerson (sp?) at VTC back in 1972 which had two tech tracks devoted to agriculture) …

    Not used except if you have a lot of cows in the exact same place as your crops. I am trying very hard to think of 18-wheelers carrying 80,000 lbs of manure from places where there are cows to places where there aint cows. Can’t think of any at the moment afaik.

    If you want better agricultural practices then you might want to better understand agricultural practices first. Just saying, if you really want no meat, no milk, no cheese, no wine, no beer, no alcohol, no … you name it. My solution involves a liquid diet such that nothing ever has to do a number two so to speak. Emm, yummy.

    Now, I am not a farmer, but if I were a farmer, then I might try to educate those here who don’t have an effin’ clue about farming. :/

  144. Willard says:

    > I might try to educate those here who don’t have an effin’ clue about farming.

    For that you’d need to make a point, Everett.

    Sarcasm and emoticons have their limits.

  145. Global warming is a wicked problem and an analysis of one part – agriculture – is no less wicked. We can predict issues of water shortage, torrential rains and inadequate rainfall that will challenge crop output. We can work on fundamental changes to the way we approach global agriculture by testing the capacity of no till agriculture that uses less petrochemical fertilizers and produces less greenhouse gas by avoiding tilling. We can look at ways to rebuild soil to maintain or increase productivity and sequester carbon. We should certainly look at the kinds of crops that we cultivate to feed billions of people. I think any reasonable review of the kinds of crops that help us build a global agricultural system for the 21st century would conclude that raising large ruminants for meat production doesn’t make much sense.

    It’s been a long time, but I think maybe Francis Moore Lappe hit the nail on the head in 1971 with her book Diet for a Small Planet. Aside from designing a diet and agricultural system for a small planet, we would need to figure out to make a guy like Ted Cruz decide that Lappe’s is his cookbook for the future. I don’t know how we would do that.

    I reviewed the comments policy for this site. The policy seems very sound and reasonable to me.


    “The Netherlands has some of the largest greenhouses in the world. Such is the scale of food production in the country that in 2000, greenhouses occupied 10,526 hectares, or 0.25% of the total land area. … Since 2000, technical innovations include the “closed greenhouse”, a completely closed system allowing the grower complete control over the growing process while using less energy. Floating greenhouses[clarification needed] are used in watery areas of the country.

    The Netherlands has around 4,000 greenhouse enterprises that operate over 9,000 hectares[48] of greenhouses and employ some 150,000 workers, producing €7.2 billion[49] worth of vegetables, fruit, plants, and flowers, some 80% of which is exported.”

  147. This Tiny Country Feeds The World

    Nice 12-page article, although don’t let the National Geographic headline fool you, as the Dutch are not literally feeding the entire world.

    EcoWatch has a sort of commentary, essentially expensive tasteless food or some such …
    The Netherlands Can Feed the World. Here’s Why It Shouldn’t

  148. Ben McMillan,

    Data-driven estimates of global nitrous oxide emissions from croplands
    (open access)

    See Supplementary data …
    Table S1 (keyword manure)
    Figure S11. Comparison of global N inputs applied to croplands between our estimates and FAO. Total N inputs are the sum of synthetic fertilizers, livestock manure, and crop residues applied to croplands. Total N inputs of this study is aggregated from the sub-national statistics, while that of FAO is obtained from national data at, where the pasture synthetic fertilizers application is removed.

    AFAIK, manure is a flatline (versus time) relative to all other known fertilizers (Nitrogen based, etceteras).

    I really do not know how to explain the obviousness of these basic facts in simpler terms. This applies to cropland N2O only.

  149. mrkenfabian says:

    Back to the original post –
    We are lagging on doing enough but there is a lot of potential for reducing agricultural emissions.

    Like everything else, a shift to low emissions electricity will have flow on emissions reductions for agriculture. Farm trucks and tractors going electric is kinda obvious – and we are already seeing some that run via retractable power cables, probably good for intensive small farms as well as battery electric. I’ve seen demos of solar powered autonomous weed spraying ‘robots’, that can also use video colour comparisons to target specific weed species and individual plants and avoid spraying other plants – saving on unnecessary “dear as poison” poison use as well as labor and emissions. Drones can also reduce vehicle use and emissions.

    Nitrogen fertiliser production seems likely to be one of the emissions lowering benefits of success with renewable Hydrogen – with “Blue Urea” – .

    Cattle methane does appear to be something that can be reduced as well. Pro-biotics to alter gut micro-biome seems to offer some benefits as, apparently, does a seaweed food supplement –

    I expect that where it comes down to it, agricultural emissions probably won’t need it but will get more time and exemptions, because farmers have political pull and will use it in an extended exercise in responsibility avoidance. (Interesting that more people in Australia vote for The Greens than the rural based Nationals, but get about 1/10th of the parliamentary representation and remain forever deemed as “fringe”. Rural electorates tend to have much less population per MP than city ones and those MPs are more likely to be conservative as well as fierce opponents of strong climate action. Interesting also that specific farming association and lobby groups like The Australian Farmers Federation support climate action and emissions targets and the main farmer oriented political party does not.

  150. Willard says:

    While weeding through my “But Greening” notes, I found back this paper:

    Agricultural research has fostered productivity growth, but the historical influence of anthropogenic climate change on that growth has not been quantified. We develop a robust econometric model of weather effects on global agricultural total factor productivity (TFP) and combine this model with counterfactual climate scenarios to evaluate impacts of past climate trends on TFP. Our baseline model indicates that anthropogenic climate change has reduced global agricultural TFP by about 21% since 1961, a slowdown that is equivalent to losing the last 9 years of productivity growth. The effect is substantially more severe (a reduction of ~30-33%) in warmer regions such as Africa and Latin America and the Caribbean. We also find that global agriculture has grown more vulnerable to ongoing climate change.

    Productivity decline and production vulnerability tend to get farmers’ attention.

    In the text the authors are underlining the importance of thinking clearly:

    Our estimates should not be interpreted as the effect of a world without fossil fuels on global agricultural production. Agriculture has benefitted [sic] tremendously from agricultural research and carbon-intensive inputs that would not have been as available without fossil fuels. The counterfactual in our study only removes the effect that fossil fuels and other anthropogenic influences have on the climate system. For instance, our estimates do not remove the direct effect that rising CO2 concentrations has on agricultural production or the presence of agricultural research or carbon-intensive inputs.

    That a source of energy leads to adverse effects does not imply that never having it would have been better. By today’s standards, life before 1900 was nasty, brutish, and short. And we know from the mass extinctions that Nature does not care much if carbon dioxide comes from humans or other species.

  151. Ben McMillan says:

    Although I think that some of the change in agriculture has to be in consumption patterns (a bit like air travel), there is a big role for tech, as Ken was pointing out .

    Greening the production of fertiliser is one thing; getting the good stuff into the crops, and not fertilising the air and the rivers is another thing. That’s something that farmers are already pretty keen on, because fertiliser is a big expense.

    (obviously, still no idea what point EFS was trying to make)

  152. “(obviously, still no idea what point EFS was trying to make)”

    You said …
    “I’m just going to note again that agriculture, and grazing animals in particular, also involves quite a lot of N2O”

    I said …
    “Not so fast, croplands and Nitrogen fertilizers provide almost all of the source materials for atmospheric N2O increases in the so-called modern era”

    Oh and that humans have known that basic fact for a very long time (fertilizers, not so much, or long in time, the atmospheric consequences of fertilizers (due mainly to our empirical atmospheric measurements starting in oh say the 1950’s, although biologists and chemists had a very good idea before those actual measurements were to begin)), that the human population has grown tremendously over the past 271 years and co-commitment with that population growth has been a similar growth in crops, croplands and plant foods for humans (and animals as a byproduct of vast excesses of plant foods)

    Which came first, the grazing animals (that humans domesticated long before agriculture (human domestication of plants) was our main food source) or the humans? Rhetorical question no answer necessary or required. Humans have been doing STEM for a very, very long time.

    We did start the fire … although Billy Joel does not think so …

  153. Grazing
    “In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed to consume wild vegetations outdoor in order to convert grass and other forages into meat, milk, wool and other animal products, often on land unsuitable for arable farming. … Grazing has existed since the birth of agriculture; sheep and goats were domesticated by nomads before the first permanent settlements were created around 7000 BC, enabling cattle and pigs to be kept.”

  154. Willard says:

    > croplands and Nitrogen fertilizers provide almost all of the source materials for atmospheric N2O increases in the so-called modern era

    I don’t think we can split grazing and croplands that easily:

    Twenty-six percent of the Planet’s ice-free land is used for livestock grazing and 33 percent of croplands are used for livestock feed production. Livestock contribute to seven percent of the total greenhouse gas emissions through enteric fermentation and manure. In developed countries, 90 percent of cattle belong to six breed and 20 percent of livestock breeds are at risk of extinction.


  155. Nice Billy Joel impersonation.

  156. Willard says:

    Aliens may not be fans of Billy Joel:

    Scientists traditionally search for aliens by listening for radio signals coming from distant planets, but NASA proposes a new method that looks for pollution.

    Scientists suggest that if an exoplanet is inhabited by a technological civilization, its atmosphere will be filled with nitrogen dioxide gas (NO2) because 76 percent of NO2 emission on Earth are due to industrial activities, such as burning fossil fuels.

    In the new study, the American space agency began by determining if NO2 pollution produces a signal that can be detected with current or future telescopes.

    From the press release:

    “On Earth, most of the nitrogen dioxide is emitted from human activity — combustion processes such as vehicle emissions and fossil-fueled power plants,” said Ravi Kopparapu of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “In the lower atmosphere (about 10 to 15 kilometers or around 6.2 to 9.3 miles), NO2 from human activities dominate compared to non-human sources. Therefore, observing NO2 on a habitable planet could potentially indicate the presence of an industrialized civilization.” Kopparapu is lead author of a paper on this research accepted by the Astrophysical Journal and published online Tuesday, February 9 in arXiv.

    From the abstract:

    Nitrogen dioxide (NO2) on Earth today has biogenic and anthropogenic sources. During the COVID-19 pandemic, observations of global NO2 emissions have shown significant decrease in urban areas. Drawing upon this example of NO2 as an industrial byproduct, we use a one-dimensional photochemical model and synthetic spectral generator to assess the detectability of NO2 as an atmospheric technosignature on exoplanets. […] Transit and direct imaging observations to detect infrared spectral signatures of NO2 on habitable planets around M-dwarfs would need several 100s of hours of observation time, both due to weaker NO2 absorption in this region, and also because of masking features by dominant H2O and CO2 bands in the infrared part of the spectrum. Non-detection at these levels could be used to place upper limits on the prevalence of NO2 as a technosignature.

  157. Ben McMillan says:

    EFS: well, it would have been a lot more useful to lead with that. Your proposition doesn’t seem to be in conflict with mine.

    The point is really that each incremental kg of e.g. beef produces a lot more N2O than many other animal products, or protein-rich crops. i.e. despite playing a minor role in world nutrition, beef production emits a sizeable minority of the N2O.

    It is a bit like the methane from beef vs. rice thing, or Australians claiming to only be responsible for a tiny proportion of world CO2 emissions.

    (Willard: we’re all going to get very rapidly confused if you start talking about NO2 instead of N2O without warning).

  158. Ben McMillan says:

    OK. The proverbial cows will never come home though.

  159. Willard says:

    > we’re all going to get very rapidly confused if you start talking about NO2 instead of N2O without warning

    Fair. I’d still prefer we talk about aliens than witness another round of halberd swings. And then there’s an astrophysicist in da house.

    The “2.5 to 5.8” range for agriculture in the Global Carbon Project graphic indicates big uncertainties. The 3.8 central number remains more than half the (central) 7.3 of the overall anthropogenic sources. Also, the proportion of N2O that goes into the atmosphere from fossil fuel emissions and the N2O that goes back in the soil from deforestation reduction may explain why Big Oil wants to plant trees.

  160. Ben McMillan says:

    Another thing that can reduce fertiliser-related emissions of N2O and CO2: growing legumes to fix nitrogen instead. Related practices can also help to build soil organic carbon.

    That depends a bit on consumption choices (people wanting to buy/eat the legume crop) and pressure on agricultural land (because grain yield might overall be lower).

    This is related to a well-known issue with ‘organic agriculture’: if you produce less output per hectare, land use increases, and this is problematic in climate terms. One obvious way to help is to reduce the land-use impact of diets, and thus reduce the need for extreme yields from crop-land.

  161. David B Benson says:

    Ben McMillan — Here in southeastern Washington state the producers rotate 2 crops of noodle wheat for the Asian market with a third year of a legume, either lentils for the local and Indian markets or chickpeas. Somebody in Asia buys chickpeas.

    The producers tell me that this 3 year rotation makes the most $ for them.

  162. jacksmith4tx says:

    Related story focused on the US Midwest farmland.
    “One third of the cropland in the upper Midwest has entirely lost its fertile topsoil, according to a new study. Other scientists doubt that figure, but agree that soil loss is a big problem.”
    “The association between soil loss and convex topography indicates that tillage-induced erosion is an important driver of soil loss, yet tillage erosion is not simulated in models used to assess nationwide soil loss trends in the United States. We estimate that A-horizon loss decreases crop yields by 6 ± 2%, causing $2.8 ± $0.9 billion in annual economic losses. Regionally, we estimate 1.4 ± 0.5 Pg of carbon have been removed from hillslopes by erosion of the A-horizon, much of which likely remains buried in depositional areas within the fields.”

    Looks like monoculture farming with gigatons of fertilizer is our future.

  163. Off topic, but seems worth noting:

    Underestimating the Challenges of Avoiding a Ghastly Future

    “We report three major and confronting environmental issues that have received little attention and require urgent action. First, we review the evidence that future environmental conditions will be far more dangerous than currently believed. The scale of the threats to the biosphere and all its lifeforms—including humanity—is in fact so great that it is difficult to grasp for even well-informed experts. Second, we ask what political or economic system, or leadership, is prepared to handle the predicted disasters, or even capable of such action. Third, this dire situation places an extraordinary responsibility on scientists to speak out candidly and accurately when engaging with government, business, and the public. We especially draw attention to the lack of appreciation of the enormous challenges to creating a sustainable future.”


  164. With gems like this …
    “While it is neither our intention nor capacity in this short Perspective to delve into the complexities and details of possible solutions to the human predicament, there is no shortage of evidence-based literature proposing ways to change human behavior for the benefit of all extant life.”
    … and this …
    “Yet, our goal is not to present a fatalist perspective, because there are many examples of successful interventions to prevent extinctions, restore ecosystems, and encourage more sustainable economic activity at both local and regional scales.”
    … you just might get this …

    … instead.

  165. Sir James Bevan, Chief Exec of UK Environmental Agency is starting to sound like a prepper also.

    “Much higher sea levels will take out most of the world’s cities, displace millions, and make much of the rest of our land surface uninhabitable or unusable,” Bevan told the annual conference of the Association of British Insurers. “Much more extreme weather will kill more people through drought, flooding, wildfires and heatwaves than most wars have.

    “The net effects will collapse ecosystems, slash crop yields, take out the infrastructure that our civilisation depends on, and destroy the basis of the modern economy and modern society.

    “If [this] sounds like science fiction let me tell you something you need to know. This is that over the last few years the reasonable worst case for several of the flood incidents the EA has responded to has actually happened, and it’s getting larger.

    Mike says: Sir James is not tracking the subtleties of flow versus stock emissions, just looking at the output and starting to sound slightly alarmed about our trajectory.



  166. David B Benson says:

    smallbluemike, “Ghastly Future” is an important read. Thank you for posting the link.

  167. Chubbs says:

    Our methane hole card is getting less valuable. Methane is currently 16% of manmade GHG, down from 24% in 1980. In the past 10 years methane has only contributed 7% to increased manmade GHG forcing, compared to 82% from CO2 and 8% from N20. All # from NOAA AGGI site.

  168. Ben McMillan says:

    I guess the question is, even if gases like N2O and methane aren’t that big a part of the climate problem, would they nevertheless be easy to reduce emissions of? Or is it not worth bothering at all?

    I think with methane and N2O there are some low-hanging fruit. And big co-benefits in environmental terms to improving certain features of agriculture and food consumption. So many bad environmental impacts of emissions associated with fertiliser use (N2O, ammonia, CO2). human health, eutrophication, climate impact. And also certain luxury food products that (unlike rice), only a small fraction of humans consume, but have a disproportionately large climate impact.

    If you split up the problem enough, all the pieces look small, and you could argue that you each of them is relatively unimportant. Like people arguing that their country/region is a small part of the problem so not worth worrying about. But clearly, that is a dead end in terms of solving the problem.

  169. David B Benson says:

    Another methane source:
    although not agricultural.

  170. Pingback: 2021: A year in review | …and Then There's Physics

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