Mythbusting: we can’t cut emissions from agriculture

Written By: - Date published: 12:15 pm, December 2nd, 2008 - 27 comments
Categories: climate change, national/act government - Tags:

This classic myth is used by National/ACT as an excuse to not do anything about climate change and, now, to attempt to undermine emissions reduction targets in the international climate change agreement to succeed Kyoto. And it is nothing more than a myth.

Between 1990 and 2005, agriculture became 30% more efficient in terms of greenhouse gas emissions. Agriculture produced $115 (in 1995 dollars) worth of goods and services for every Kg of carbon (or carbon equivalent) emissions in 1990. By 2005 that had risen to $150 per kg of emissions. That 30% improvement in carbon intensity is actually better than the economy as a whole, which had a 24% improvement.

(sources: mfe, stats)

As, you can see the improvement in carbon intensity for agriculture went flat in the last few years, probably because the switch from lower-carbon crops to dairy has counteracted general improvements in carbon efficiency. But the fact remains, we can and we have cut the amount of greenhouse gas we emit for each dollar of agricultural production.

Of course, because production is growing the actual emissions from agriculture have grown even as carbon intensity has improved. To actually reduce emissions we need to improve carbon intensity faster (or stop growing production). That’s not impossible, carbon intensity is improving anyway, we just need to invest in research. Unfortunately, our new government is set to destroy the multi-billion dollar Fast Forward Fund that was established to do just that.

Remember, when National/ACT says that we can’t reduce emissions from agriculture they are wrong, and they are the ones who are preventing further progress. They simply have no commitment to fighting climate change.

27 comments on “Mythbusting: we can’t cut emissions from agriculture”

  1. Phil 1

    the improvement in carbon intensity for agriculture went flat in the last few years, probably because the switch from lower-carbon crops to dairy has counteracted general improvements in carbon efficiency

    Wrong. There have been a farm conversions in NZ over the last couple of years, mainly due to the attraction of high milk-solid prices. However, those conversions have been from sheep and beef farms to dairy, not horticultural growers. It’s a falacy to claim earlier than ’05 is impacted by conversions.

    Looking at 1990 (and 1993 as well) you are using a poor choice of base year, so any productivity improvement is impacted by a significant ‘base effect’.
    IIRC, those two years had severe weather (snow storms down south too?) that did a lot of damage to stock and crops and would therefore depress the production/CO2 ratio.

  2. Phil. I’m using the year that the stats go back to.

    Are you denying that agriculture has become less carbon instense?

  3. Hi Steve, I am trying to replicate your graph but I’m not sure how you got those numbers from the sources you cite. How did you manage to extract agricultural emissions from the list of NZ’s total emissions? If you could give some more details I’d much appreciate it.


  4. Lanthanide 4

    I think it is pretty clear that 1990 and 1993 look like outliers in the given data. The years of 1991, 1992, 1994 and 1995 were all up around 140. Say that you use 1991 as your base year, instead of 1990 – then the improvement is only 7%, which is much less than the 30% you like to point out, and much less than the 24% that the rest of the economy showed. Before you go spouting off about a 30% improvement based on this set of data, you should investigate these outliers and see if there is any obvious reason for them – weather being a likely bet – and then see if this has any affect on your position.

    I really do like this blog, but sometimes I think you do yourself a great disservice by posting things that have glaringly obvious flaws.

    [lprent: No-one is perfect, and we’re writing opinion pieces in our spare time. Sometimes facts or assumptions may be wrong. That is why we have a comments section. BTW: Haven’t looked at the posts yet, so this is a GENERAL observation]

  5. rauparaha. sorry, I’ve linked to the overall emissions page. in the left column there is a ’emissions by sector’ page, click there.

  6. Tim Ellis 6

    SP, John Key’s point is that New Zealand already has the most carbon-efficient agriculture in the world. Unlike power generation and transport, there are few further options available to use technology to significantly reduce carbon emissions from agriculture in New Zealand. So what happens if you include agriculture in the ETS? New Zealand farming becomes less competitive than overseas. New Zealand food production drops (just as the world has been facing food riots in several cities this year). Food production is transferred elsewhere, where their agriculture isn’t negatively impacted by the ETS.

    By all means tax carbon emissions in industries that are being treated fairly across the world, where there are significant technology gains to be made in those industries, and where there aren’t major potential humanitarian effects on that activity.

  7. Rex Widerstrom 7

    So hang on… are we debating the virtue of excluding agriculture from any ETS (as Tim Ellis suggests) or of kneecapping the Fast Forward Fund and thus any further research into reducing carbon emissions by agriculture, as Steve mentions in the original post?

    Because the former would appear to be an arguable proposition given the potential impact on the economy, whereas the latter just seems incredibly short sighted penny pinching, given the advances that have clearly been made, and the relatively paltry saving.

  8. Interesting analysis. The problem is however that Kyoto does not deal with “carbon intensity” – if it did we’d be away laughing as our carbon emissions per kg product are far lower than those of our competitors in Europe. If the global system were changed to be based on carbon intensity rather than absolute emissions we could actually use these figures. But until then it is fun speculation that does absolutely nothing to change our massive Kyoto bill.

    Part of that increase in $ per kg C will be pure inflation. The milk price increased substantially over that period. Any efforts to produce “value-added products” such as chilled meat rather than frozen will also affect the figures. So it is difficult to actually tell what your figures mean – have carbon emissions actually reduced or are farmers just getting more money for their products?

    A far more useful analysis would be carbon emissions per unit output.

    In order to satisfy Kyoto, we aren’t able to say “look, our carbon intensity is improving, aren’t we great”. We are expected to actually reduce total emissions. We can partially reduce emissions in some situations using nitrification inhibitors, changing farm management, and doing various things like that. But we have no practical way of seriously reducing methane emissions, our largest source of emissions, unless we kill all our sheep – and that won’t be happening any time soon.

  9. Phil 9

    Are you denying that agriculture has become less carbon instense?

    I’m going to have to be careful here – I supect that was the first step in a cunning plan to back me into a corner, where I end up arguing a point ‘further left’ that where you started from…

    Farm conversions (from sheep/beef to dairy, not horticulture) have increased quite a bit over the most recent seasons, after milk prices really went crazy. But, conversions take time, and have to be done in the right season, so I think ’05 is too early for that to have an impact on your data.

    As a result, there is going to be very little compositional effect between, say, 1999 and 2005. Over that period (assuming your maths is right!) real output per Kg CO2 are essentially flat. So in that respect; Yes, I am denying Agriculture has become more efficient.

    However, as pointed out by Tim, we already have some of the most efficient Ag production in the world.

  10. Robin Grieve 10

    A cow recycles carbon she does not produce it. The carbon becomes grass which becomes milk etc which grows bones in children etc. Some carbon returns to the atmosphere from where it came as methane which then breaks down into carbon which becomes grass and so on.
    A cow does not create one single molecule extra of carbon so can not have any effect on global warming which is supposed to be caused by increasing carbon in the atmosphere.
    In fact carbon from some of the milk we drank as children is stored in our bones and bodies until we die but the farmer gets no credit for that even though they should.
    Anyone who thinks livestock methane emissions could cause global waming did not stay at school long enough to learn the carbon cycle. It just goes around and around and to want to clip the ticket each time is immoral.
    The only carbon emissions that can cause global warming are produced from burning fossil fuels.
    That is your lesson for the day, next week we will do more 4th form stuff.

  11. George Darroch 11

    Thanks for that helpful and informative lesson Robin Grieve. Perhaps later in the week you can teach that very simple 4th form science to scientists who spend their time dealing with agricultural emissions, and tell them where they’re going wrong. I’m sure they’d appreciate it.

  12. George Darroch 12

    I tend to agree with Lathanide. What I see is a significant improvement in the early 1990s and then production per unit of emissions holding essentially flat since 1996.

    “However, as pointed out by Tim, we already have some of the most efficient Ag production in the world.”

    Tim, John Key, Phil and quite a few other people have made this claim. It appears that the meme can be traced back to a survey conducted by Massey, which compared total emissions for UK products and NZ products flown to the UK. The NZ products came out ahead in most categories, but this is in no way a claim about “best in the world” rather simply a claim that food miles are simplistic.

    If there is research that compares different countries and establishes which come out on top I’d be interested to read it.

  13. gomango 13

    George – I’m looking for the logic fault in Robins comment which you can identify, but I cant. Can you please explain?

    Could it be that ETS is a flawed system which has anomalies due to the baseline chosen (amongst other things – don’t get me started on Russia, China, India, EU, US)? There are lots of anomalies possible. Cutting down a tree is actually good for the environment (if you carefully store the wood as framing in a building) yet under ETS you are no worse off if you use it as firewood. And, the reason I never mow my paddock is because I am committed to creating a carbon sink in my neighborhood. Bring in a carbon tax – that will change behaviour. Nothing else will.

  14. Robin Grieve 14

    Yes the Kyoto and the minority of scientists that support it are wrong.

    For example under Kyoto rules the carbon emission of mowing a lawn of 1000 square meters is about 3.0kgs of CO2 emitted to the atmosphere.
    To graze that same lawn with a sheep will emit as measured under Kyoto rules the equivalent of 19kgs CO2 to the atmosphere
    According then to Kyoto it is better for the environment to use a petrol gussling lawnmower than a sheep. This is clearly absurd and wrong.
    The problem is they do not differentiate between the two emissions as they should. A lawnmowers 3.0kgs CO2 is new to the atmosphere and therefore could cause global warming. (it has increased the net CO2 in the atmosphere) The sheep emission however is not new, the CO2 came from the atmosphere and the sheep just returns it.(no increase)
    So you see they are wrong and anyone who subscribes to the theory that livestock can cause global warming supports the absurd notion that it is better for the environment to mow our 10 million hectare of pasture with lawnmowers than graze them with livestock.

  15. Stephen 15

    Well they wouldn’t count the sheep at all, because no one gives a toss about anyone keeping a sheep in their yard except perhaps public health officials or some such thing.

    Yes the Kyoto and the minority of scientists that support it are wrong.

    Kyoto is a policy instrument informed by the science of climate change, so it’s more a negotiated political agreement than anything – it doesn’t really need scientists to support it, therefore once they’ve provided the scientific information, they are not really relevant are they? It’s all ‘risk management’ from there.

  16. Stephen 16

    Some carbon returns to the atmosphere from where it came as methane which then breaks down into carbon which becomes grass and so on.

    Any idea how long it takes to break down into carbon dioxide? Do you think it’s facilitating any warming while it’s waiting to break down? Even when it becomes CO2 it’s still causing warming, innit?!

  17. Stephen 17


    Remember, when National/ACT says that we can’t reduce emissions from agriculture they are wrong

    This post isn’t really all that specific though is it? Like Mr Dennis says, there are methods like “nitrification inhibitors, changing farm management, and doing various things like that” but they aren’t close to widely applicable right now – what’s your idea?

  18. Tim Ellis 18

    Robin said:

    A cow recycles carbon she does not produce it. The carbon becomes grass which becomes milk etc which grows bones in children etc. Some carbon returns to the atmosphere from where it came as methane which then breaks down into carbon which becomes grass and so on.
    A cow does not create one single molecule extra of carbon so can not have any effect on global warming which is supposed to be caused by increasing carbon in the atmosphere.

    I think your science is wrong Robin. You are quite right that cows do not produce any carbon “molecules”, although carbon is an atom. CO2 and Methane are molecules, however, which cows do produce.

    Carbon is not just recycled from grass to milk, I’m afraid. Carbon is consumed from the grass (a carbon sink, in grass form it is not in the atmosphere), and then some of it is transferred to milk. But much more of the carbon is used to produce methane, particularly in the bovine gut, which is emitted to the atmosphere through belching. As cow manure decays, it also emits large amounts of methane.

    If the cow did not exist, then the grass would have continued to grow, creating a larger carbon sink (removing the carbon from the atmosphere).

  19. Ron Shaw 19

    Regardless of your position on the science or the politics of ‘global warming’, ‘climate change’ or whatever you want to call it, the policy makers in the EU are drafting regulations based on an acceptance of climate change. These regulations will be used as non tariff barriers against New Zealand. The EU have even suggested ignoring their WTO obligations and placing countervailing tariffs on “high carbon footprint” imports.
    To counter the hypocritical nonsense that passes for policy in Europe, NZ has to be seen to act on greenhouse gas reductions even though we are small polluters in any absolute sense and greenhouse gas reductions are a very inefficient way of addressing the impacts of climate change.
    Parking the ETS, flawed and rushed as it was, plays to domestic concerns without taking account of NZ’s wider interests.

  20. Phil 20

    If the cow did not exist, then the grass would have continued to grow, creating a larger carbon sink (removing the carbon from the atmosphere).

    That’s only partially accurate Tim – once any living plant (grass, tree or otherwise) grows to its natural maturity, its capacity to remove more carbon from the atmosphere diminishes significantly. From first hand experience, through personal laziness and not mowing my lawn, I can tell you that grass grows to maturity very quickly!

  21. PK 21

    Sorry giant post – feel free to fall asleep during reading of it – there will be a written test however …. 🙂

    There is a lot of muddied thinking around emissions in general confused I reckon by the artificial mechanisms used to determine contribution to emissions and how this then translates back to Kyoto or the ETS i.e. the implementation is wrong and unrealistic.

    Methinks .

    • The whole point around emissions is net contributions.
    • Some emissions decay, in particular methane which has a half life of 7 years
    • Where there is an emission that decays and the rate of production is constant then the net contribution will be steady after about 4 half lives actually about 95% of the final figure but increases to net contribution are slow after four half lives (I think I remembered my exponential decay equations correctly)..
    • So, if you have a cow (and its replacements) producing the same amount of methane then ones cow’s net contribution is, to all intents and purposes, steady after 30 years.
    • If a cow eats grass the net reduction in CO2 overall is the difference between the CO2 fixed in the grass when grazed and when allowed to grow to full height minus the carbon fixed in the cow this is not a lot and if in a steady state i.e. same number of cows and same size of field, has no further net contribution after the grass was initially grazed and the cow installed.
    • Plants make no significant net reduction in CO2 once the plant is established as plants grow, die, decay, grow again etc. So, once say you have, say, a lawn that’s it your sink is fixed in size but varies in how much it fixes within a fixed range periodically.
    • There is a very small amount of, effectively, permanent fixing of CO2 by plants but it’s tiny and slow and can be ignored in the sort of timescales we are discussing
    • The fixation of CO2 has a high correlation with weight i.e. lots of plant material has lots of carbon thus the reason forests are bigger sinks
    • Cows generally aren’t grazed on quality land that can reasonably grow crops is my understanding (not a farmer so I am not super confident saying this) so one needs to change grazing land to forests to get any significant increase in CO2 fixing.
    • There are net emission contributions with associated agricultural activities that require energy that come from fuel sources that are net emitters e.g. fuel to take the cow to the slaughterhouse.

    This implies

    • Changing from a forest to a field has a net contribution to emissions as fields fix less CO2
    • Increasing the number of cows (or their size) increases the net contribution if the methane production is proportional to size, which it currently roughly is
    • The argument over requiring x kilos of plant material to make beef versus y kilos if used to make vegetables, rice etc is a bit of a red herring in an emissions discussion (sometimes dropped in) the as the plant material fixes CO2, gets eaten decays etc independently of whether there was a cow in the middle. The issue is the cow itself and its contribution to net methane levels and any associated energy use specific to cow production greater than that associated with the plant production.
    • It’s changes of use that are net agricultural contributors vegetable to animal, forests to crop, bigger cows (same as having more cows). Once that change has occurred all other emission contributions are related to associated energy use in the longer term

    Also, remember energy use, overall, is a net contributor.

    We can only reduce our agricultural emissions (ignoring energy use for the moment) if:
    • We can design cows that emit less methane (actually achievable to some extent and a good thing as methane production comes from an anaerobic reaction that is less efficient i.e. it would make cows more efficient)
    • Design plants that fix more CO2 per square metre i.e. bigger plants or more dense growth
    • Change the agricultural use to one that fixes greater net CO2 e.g. switch from grass to trees
    • Reduce the number of methane emitters i.e. cows

    That’s it and some of the options require (roll of drums) GE to be effective though there have been effects by changing cow feed but these appear to require currently uneconomic feeding mechanisms.

    I have deliberately ignored reduced emissions contributions that come from associated energy production reductions as the agricultural sector don’t have a lot of influence over this (the odd windmill perhaps) and this is really a discussion about the direct agricultural contribution.

    The fact that we have doubled our cow population in 40 years (from memory) and lets assume they are 30% heavier means that if we were looking at net contribution about 40% of the cows contribution should not be included in our emission figures as they did their net contribution it’s already there adding them in each year is invalid. They are not making any more emissions faster than they disappear. Of course, this does not happen we have our emission use measured based on yearly and not net contribution.

    The problem is, if I become a more efficient dairy farmer then I will have more cows per acre and will become an even greater net contributor. It’s probable that any reductions in methane production (remember CO2 is a red herring here for growing cows once the grass is grazed) through design or feed changes in cows will be more than made up for by an increased number of cows. So we can only really live up to our Kyoto obligations related to cows by reducing cows i.e. one of our few competitive edges and money spinners.

    In terms of other agricultural mechanisms to reduce our net contributions we could grow lots of forests actually change land use. But that requires large capital investment and 25 years without income. The returns have been pretty bad for a while and it’s only currently feasible in NZ because of the tax breaks. The ETS gives some funds as one can sell the credits but will they be enough. Not sure but it doesn’t look like it on current plans.

    We could try and change grazing use to crop use but based on my limited knowledge I don’t think that’s very achievable.

    In all of this we should remember NZ earns a lot of money from cows and agriculture. This in an environment where we have to compete against quotas, tariffs, subsidies etc and where the likely outcome of us living up to the $ of Kyoto or taxing our farmers with carbon emissions will just make us less competitive and I promise you the US, EU, China and India will not play fair. US and EU will continue with their posturing on free trade whilst implementing protectionism in agriculture and China and India (who will be huge emitters) will quite rightly tell the rest of the world to go s**w themselves as it’s a choice between starving locals or a ½ a degree difference in temperature ..

    And Steve you cannot necessarily equate increased profitability with increased emission efficiencies. There are too many other factors that could have led to increased profitability e.g. the exchange rate, increased demand pushing up the real price.

    However Steve, as you stated it’s obvious one can reduce overall agricultural emissions (not based on your logic though) I just don’t think we want to as it will quite likely beggar us with the current approach.

  22. Robin Grieve 22

    You are all getting carried away . Remember it was claimed by some that global warming would occur because carbon in the atmosphere was increasing as we burnt fossil fuels.
    Cows do not increase carbon so therefore no possibility of global warming. That some carbon becomes methane and then carbon is a red herring as there is no net increase which what global warming is all about supposedly.
    In fact a cow removes carbon from the atmosphere as she grows from a 40kg calf to a 500kg cow, that is all carbon locked away for 12to 14 years before she dies and is eaten by a growing child who locks the cows carbon up in it’s bones for 70 to 80 years. That is better than a tree.

  23. PK 23


    a much shorter version of what I said except that methane emissions are also contributors (assuming you agree with the global warming premise) and do increase the net greenhouse gases when you add an extra cow to the world.

  24. lprent 24

    RG: Wrong – it is from all of the impacts of humans on the carbon cycle and its impact on greenhouse generating gases.

    Sure burning fossil fuels is a major part of that. However so is chopping down carbon sinks like forests and releasing the stored carbon as CO2. For instance there was the 1997-8 burnoffs in indonesia. Estimates of the effect of those that they were at least 13% of the CO2 released that year. Those burnoffs continue. They do in all sorts of areas.

    Draining peat bogs also releases a bloody great big pile of atmosperic carbon. Probably more than deforestation. It is just harder to measure because it doesn’t have the isotopic signature of fossil carbon.

    What has been surprising with the CO2/CH4 levels is that they haven’t risen as fast as you’d expect over the last century as the human population has grown from slightly more than 1 billion to 6.5 billion. However the early releases appear to have been filling up the buffers in the carbon cycle, like cold ocean currents sedimentation etc.

    If there isn’t a corresponding re-sequestration of that carbon into other carbon stores, then the level of atmospheric carbon goes up. That is what the increase in atmospheric carbon prior to the 1950’s with increased fuel consumption and land-clearing did. However that rate of release since then has shown a steady reduction in the adsorption rates, so more the the released carbon is staying in the atmosphere, trapping heat, and modifying the climate.

    The problem is that we have no idea when we’re going to hit a tipping point. That is when the rate of climatic change is such that it starts releasing other climatic change agents. For instance ocean current changes starting to release solid methane on the arctic ocean bed, or desertification in the tropics releasing more carbon, or changes in the cold/warm currents in the oceans.

    However we do know that it will eventually happen because it has in the past. Anyone who has studied paleo- climatology is aware of this.

    Anyone who has studied the relative climate stability that our culture has relied on for the last 10k years is also aware of how closely our socities rely on that stability. I don’t think that they’d survive a big climate shift, and I think that without change we’ll get one in either my lifetime or my childrens.

    With the exception of the climate change deniers*, the acceptance of the problem has been become widespread since I studied it in the 1970’s in a earth science degree. The argument is about the best way to handle it.

    * In my view most CCD’s are generally total dorks about how they argue this topic (and usually don’t seem to know much about the topic either). They scream headlines like “31k scientists” without bothering to find out how many of them have any expertise in the area (or in a lot of cases if they even know that they’re on this list). Whale is a prime example – saw the moron exposing the blubber level between his ears today.

  25. PK 25

    Hi lprent

    bit of a rant there – perhaps a coffee overload? Not defending RG as I don’t know the guy but looking at his arguments…

    – he’s right in saying that cows are not a CO2 issue
    – he missed the emission contribution from methane
    – you had lots to say about elements he did not bring in to the discusion but you listed them as if he was arguing against them

    anyway – I’m sure you feel better now 🙂

    The one comment I would make is about the almost religious aspect of the whole climate change discussion and the entrenched views – we have terms like deniers (I forget the equivalent pejorative term for the opposite view). Keeping with the religious theme I would say that an awful lot of people are agnostic – and considering the poor record of science in the public domain over the last 40 years they are right to be so. Acid rain turned out to be an non event, the next ice age of the 70s is now global warming etc. Would you have any faith in this based on past experience and why would you?

  26. lprent 26

    PK: I was actually arguing against the statement (and yeah I should have quoted it)

    Remember it was claimed by some that global warming would occur because carbon in the atmosphere was increasing as we burnt fossil fuels.

    Obviously that isn’t the whole case. Even if there weren’t any fossil fuels being burnt, then there would still be an issue. Current land use would probably lead to similar effects. It’d just take longer. There is a  problem with sustaining the current levels of population with current farming and other land use.

    The probably part is to do with the buffering systems. No-one is too sure about exactly what the sequestration levels are. The only thing we’re sure of, is that with the levels of fossil fuel usage on top of land-use, is that we’re currently exceeding them by a significant amount. Otherwise we wouldn’t get the CO2/CH4 rises in the atmosphere we’re seeing at present.

    However in my lifetime human population has more than doubled from less than 3B to more than 6.5B. That has had consequent changes in landuse from high carbon sequestration to high release. I suspect that we’d probably be increasing CO2/CH4 levels in the atmosphere even without the fossil fuels.

    To control or even reverse the atmospheric changes, then land-use has to be part of the changes that get made (along with cement production and a number of other things)

  27. Robin Grieve 27


    You raise a lot of things oceans releasing methane etc. There is a lot of natural cycle stuff and one problem is when you link lots of things back to one argument it tends to get blown out of all proportion.

    The points raised about agriculture and livestock emissions contributing to global warming are all speculation. There is not one study anywhere in the world that links such emissions to global warming. The point an extra cow increases emissions fails to factor in that that cow is going to eat grass before any emissions occur putting it in credit. And remember any extra cow is going to lock carbon away for a long time in her bones. The point that there were 3b people and now there are 6b raises the point, what are they made of? Carbon is the building block of life it is not a polllutant. As the population grows we are going to lock up even more carbon.

    So there are in my view more questions than answers but the main point it is all just speculation. No one knows least of all those who designed Kyoto. (check out my previous post about the lawnmower and the shep to see how wrong they have got it)

Recent Comments

Recent Posts