Methane technology breakthroughs cannot stop cannot ruminants from doing what comes naturally
Reducing methane production from pastoral agriculture lies at the heart of efforts to make pastoral agriculture more climate friendly. If only sheep and cattle could be made to stop producing methane!
Here I look at the challenges of making this happen. Unfortunately, those challenges are not easily solved. It is a lot harder than the uninitiated might think.
This is not just an issue for farmers. It is also an issue for all New Zealanders, given that almost half our exports come from pastoral agriculture – currently more than $32 billion per annum. According to MPI, approximately 82 percent of all exports come from primary industries once timber, fish, horticulture and wine are included.
Without primary industries in general, but particularly pastoral agriculture, we are in very big trouble as to how to pay for all the imports of goods that we cannot produce here in Aotearoa New Zealand. Solving the methane issue would be a real big deal.
The starting point to understanding something about methane is to appreciate why ruminants produce methane. The quick answer is that it is a fundamental component of how ruminant animals, with their distinctive four-stomach system, have been designed by nature to digest grasses.
For humans, pigs, chickens and other species with single stomachs, known in biology as ‘monogastrics’, it is not possible to digest grass efficiently. Accordingly, if humans try and eat a meal of grass, they will get a sore stomach and very little sustenance. Indeed, it is simply not possible for humans to survive on a grass diet.
In contrast, ruminant animals such as sheep, cattle, goats and deer have a four-stomach system, designed by nature through evolutionary processes so as to be able to digest grasses and other high-fibre forage crops that contain cellulose. The ruminants do this with the help of trillions of bacteria that live within the rumen system. These bacteria ferment the cellulose in the grass to form volatile fatty acids which can pass though into the bloodstream of the ruminant.
This process of ruminant nutrition leads to carbon dioxide and hydrogen as waste products. At this stage another group of micro-organisms called ‘methanogens’ come into the picture. They turn the waste products into methane, with four hydrogen atoms attached to each carbon atom. The ruminant then burps up the colourless odourless methane.
When nature first designed ruminants through evolutionary processes, there was no need to minimise greenhouse gases. These gases only became an issue once humans interfered with natural processes by digging up huge quantities of fossil fuels that had been buried for millions of years.
Modern science tells us that it is water vapour first and then carbon dioxide that are the main greenhouse gases. But methane also happens to be a greenhouse gas that absorbs infrared rays at specific wavelengths as they travel back from earth into space. So methane, which ruminants have been happily burping for millions of years without a problem, are now considered to be part of the modern greenhouse gas issue.
The problem is that nature’s ruminant nutritional system was designed for a purpose over millions of years by trial and error. That is how evolution works. And nature does not necessarily take kindly when humans want to interfere with the basics of that ruminant system. Change part of the system and there is always a good chance that the overall system will fall apart.
One way or another, the excess hydrogen has to be removed from the rumen. Otherwise, the rumen will turn from a fermentation vat to an acid vat. The animal will not be impressed and will get very sick.
Accordingly, it is not just a case of killing the methanogens. Something else has to take over the job that the methanogens do naturally. If there was an easy solution that was energetically better than producing methane, then nature would in all likelihood have figured that out itself.
So, what are the technologies that humans have been exploring?
One of the most fascinating technologies is to feed some bromoform-releasing seaweed to ruminants. These trials have been going on both in New Zealand and overseas. The bromoforms are particularly good at killing off the methanogens, but unfortunately, they tend to also mess up other parts of the rumen system. Particularly important is the finding in a recent scientific paper that bromoforms pass from the rumen into milk.
Alas, bromoforms are a suspected carcinogen and certainly have the ability to interfere with many human processes. My own assessment is that, despite some ongoing hype, there is close to zero chance of this technology being acceptable to food-safety authorities. Indeed bromoforms, which are similar in their action to chloroform, are already widely banned in foodstuffs.
The second feed additive that has generated considerable hype is a chemical called 3-NOP. This has been developed through to early-stage commerciality by Dutch firm DSM with the trade name Bovaer.
This technology appears to be much safer than bromoforms and does reduce methane production in feedlot situations for dairy and beef cattle. However, the evidence to date is that it does not work under pastoral conditions because it needs to be evenly distributed throughout the feed.
Fonterra has been working with DSM to try and develop the technology for pastoral situations. The barriers are formidable. Whispers on the breeze are that Fonterra’s research has not gone well and that there are some very glum faces. At the very least it is a long way from commercialisation for pastoral conditions. Also, there are good scientific reasons as to why it is highly unlikely to ever work anywhere near as well in pastoral situations as it might do in a feedlot.
The other area of hype which has been around for the best part of two decades is a vaccine that leads to methanogen destruction. Research has shown that it is possible to get the animals to produce antibodies that travel via the saliva to the rumen, but getting the antibodies to actually work in the rumen is another matter. This technology has remained somewhere out beyond the ten-year horizon for more than a decade and commercialisation has not been getting any closer. Once again there are some glum faces.
Another technology has been genetic selection for low-methane-emitting sheep and cattle. This is definitely feasible and may be a modest success. In sheep, where the research is most advanced, the lower-emitting animals have smaller rumens and produce more propionic acid than what occurs in the higher-emitting animals. Also, it seems these characteristics are inheritable.
However, there will be limitations to how far that technology can be taken. There are good reasons why fatty acids other than propionic acid, and which produce more methane, also have to be produced. It could be a useful tool in the toolbox but once again there is some risk that it is being over-hyped. Caution is appropriate until there is more evidence as to how these animals perform under rugged pastoral conditions.
Pulling all of this evidence together, the big picture is that there are no magic technology bullets that can drastically alter the reality that ruminants emit methane for a good reason. This methane is the outcome of evolutionary processes that produce animals that are fit for the grassland environment in which they live naturally.
However, that does not mean that no progress can be made in terms of emitting less methane per unit of meat and milk output. Indeed, the last 30 years have produced an amazing but seldom told New Zealand story as to how methane emissions per kg of sheep meat have reduced by about 30%. Dairy emissions per kg of Milksolids (fat plus protein) have reduced by about 20%.
The way these spectacular efficiency improvements have been achieved is by the breeding of more productive animals and incorporating these animals within improved farming systems. Fortunately, improved biological efficiency has also led to efficiency improvements relating to methane emissions.
In the coming years there will be further improvements to be gained in relation to reduced emissions per unit of output, but it will be hard work. Each percent of gain is more challenging than the previous one.
One particularly promising field of endeavour is the methane produced in effluent ponds rather than inside the rumen. But across the all-species ruminant system, methane from effluent ponds comprises only about 4% of the total methane emissions.
None of these advances will change the bottom line that there will be no magic methane bullets. As long as ruminants live on the grasslands, they will continue to do what nature designed them to do, and that includes emitting lots of methane.
Given that reality, together with the fundamental importance of pastoral agriculture to the export-led economy, there is lots to ponder.
Thanks Keith, a great summary.
I work in the nutrition field and that is a question I’ve been asking those promoting the doing-in of methanogens for as long as it has been a question, i.e. how will the ruminant get rid of those pesky protons? I’ve usually been told one of two things:
1. The protons are not a problem. Clearly not or the animal wouldn’t expend so much energy getting rid of them, or
2. Ever more rumen buffer. With half of grass fed dairy cows suffering from SARA and most confined cows suffering at least SARA and sometimes clinical acidosis sometime in their lactation, this isn’t really a great situation. I know nutritionists already feeding twice the recommended limit of buffers and cows are still showing symptoms of low rumen pH. If you take away part of the cows natural pH buffering mechanism it will become more of a problem.
It would be a great situation for agriculture to be able to say enteric methane is no longer part of the problem but there is some way to go yet. Also, you have said it before but it must be repeated at every turn, if we reduced enteric methane to zero today, it would only give the long lived greenhouse gas emitters, e.g. CO2 an excuse not to do anyhting for a while yet. In 20 years time when the effect of reduced CH4 has gone, we would again wonder why we hadn’t dine something about it earlier.
1) higher energy higher lipid content grass reduces methane emissions per kg DM but some of these are GMO. Why was that option not mentioned? Aggressive development and implementation of gene-edited technology in plants should surely be towards the front, not omitted from the list.
2) As you note have made great progress increasing productivity of NZ sheep since 1990 and also indirectly reducing methane intensity as well. Slow but steady gains. https://beeflambnz.com/sites/default/files/data/files/Compendium-22.pdf Lamb meat production in 2020 expressed as kg/ewe was +118% in 2020 compared to 1990 and methane emissions per tonne of carcass weight was 35% less. This change was made against a backdrop of “sheep are a sunset industry” and “if you select on BLUP selection indexes they will become mongrels”. As a person involved in those genetic changes I see no reason why similar progress cannot be made to increase sheep productivity while also reducing the methane emissions per animal.
If we combine say a 15% change in methane emissions (~0.5%/year) from animal genetics by 2050 while also improving productivity and obtain another 15% from improved forage we could achieve the targeted change required in methane and increase animal productivity as well.
Is much more work required? Of course. Similarly, multiple approaches should be investigated to reduce risk.
It is tragic to see where NZ is heading. A beautiful country with a strong economy being destroyed from within by reductionist policies. The speed and direction of travel suggests that soon the peoples will be unable to feed themselves or heat their homes, and all for a tiny, invisible molecule, the latest ‘enemy’ that must be defeated. Oh how the greed and hubris of man has lead to the destruction of civilisations in the past and how we have come, yet again, full circle to repeat the cycle. But I could be talking about the UK, where I am, too, or most western societies. All intent of dragging their populations back to the Middle Ages in the name of defeating the ‘enemy’. It is not the ‘enemy’ that is causing our woes, but the policies enacted to try to defeat it. Now we see the destruction those policies are causing, surely it is time to consider: is the cure going to be worse than the cold?
Hi Christine. I agree with a large part of what you’re saying, ie that governments seem to take the ‘bash the farmer’ approach all too often. Agriculture has been too good at increasing efficiency of production and therefore there are too few votes to care about.
I think that, as we have seen in Germany with coal derived electricity, as soon as the pressure comes on, the government will find what was unacceptable, acceptable again.
Every government knows that the best way to get people on to the streets is to have empty supermarket shelves. We’ve had it so good for so long because of increased efficiency in agriculture. This has led the government to believe that whatever they do to farmers, the shelves will always be full. It has worked so far but looking at the food supply/consumption balance, it might have to ease up soon.
Agriculture has its part to play in turning around climate change but everyone needs to play their part and governments shouldn’t just pick the low hanging fruit, they need to get up the ladder as well.
If you examine the FAOs inflation adjusted cost of food over time you will note that it declines about 30% from the 1960s until about 2008. Many reasons but include the green revolution (fertilizer, pesticides, improved animals and plants, more international trade). In summary these improvements outpaced quite rapid population growth over the same period. This has snapped back into balance over the past decade and the current trends are not looking favorable for consumers. Aggressively mitigating green house gas emissions while also trying to improve food production will likely raise the real price of food further until the world population stabilises. As you allude to this quickly results in political instability. These energy, protein and nutrient constraints, plus linked financial supply and demand curves are often glossed over. We live in interesting times.
Keith, is there any hope for NZ to rethink our methane targets?
If we used GWP* as recommended by the Intergovernmental Panel of Climate Change (the worlds leading authority on climate change), we wouldn’t have such a high reductions target for methane and there would be no need to interfere with the natural processes of ruminants. Beef and Lamb NZ have repeatedly advocated for GWP*, and if used, a 0.3% reduction in methane yearly would be the equivalent of being net zero.
As a first time commenter, your comment got caught waiting to be approved . My apologies.
These are actually two different questions you ask.
The answer to the first one about the targets is ‘yes’. Those targets are due for consideration by GOVT in 2024 but whether or not any change might occur I cannot judge. It might depend on who is the Government at that time.
The issue of GWP* is a lot more complex. The IPCC report includes discussion of GWP* and its characteristics as a metric of measurement, but it is not correct to say that they advocated its use. Their job is to report on the science, not to advocate for specific metrics, all of which have value judgements associated with them.
Whether or not it should be used internationally would be a decision of the UNFCCC and to the best of my knowledge they have never given that consideration. But I can assure you that there would also be lots of opposition within UNFCCC to its use, related to the way it grandfathers historical emission patterns. This goes very much against the Paris Accord commitment towards developing countries who have historically had lower emissions than developed countries.
There are at least 12 different measures of CO2 equivalence, with GWP* being just one of them and all of them suffer from the challenges of trying to compare ‘apples to oranges’.
Most people only read the short Summary for Policymakers, which is just 32 pages and not allowed to be written purely by the scientists but including Government reps, so is really a politicised version of the full report which stretches to a whopping 2409 pages, and is thus rarely read in full by anyone outside the original authors and the Government reps.
In the full report Climate Change 2021: The Physical Science Basis page 1016 it says “methane emissions as CO2 equivalent emissions using
GWP-100 overstates the effect of constant methane emissions on
global surface temperature by a factor of 3–4” quoting as their source Lynch et al 2020. This fact is not in question. The problem is that it is ignored and in the Summary for Policymakers the word ‘methane’ is only mentioned five times and none references the flaws of using GWP-100 and how this mis-represents and far overstates the impact of cows on the environment.
Given that it would appear removing domesticated bovines as a key source of nutrient dense food from the animal-sourced food options in future, I can’t help but to agree with Peter S and that ignoring this issue plays very nicely into the hands of those who demonise cows.
The IPCC should not be ‘advocating’ anything, they should just be stating the facts as best and as broadly and non-selectively as ‘the science’ allows. It does unfortunately appear that the IPCC has become politicised and this is going to be catastrophic not just for this sector of the farming industry but for those who choose to consume these nutritious ASFs.
I have page 1016 of the AR6 report in front of me and I know that and surrounding pages well. It is important that the sentence you quote (actually part of a sentence) is understood in context. It is also important to understand that the statement relies on grandfathering of historical emissions. For example, in NZ’s case, it is based on, as NZ’s historical ruminant methane emissions decay to CO2 and water, and hence the temperature effects of those emissions decline, that NZ can replace those historical emissions with new emissions that will thereby stop the cooling that would otherwise occur as those historical emissions decline. In effect, GWP* would allow developed countries like NZ to continue emitting ruminant methane but would penalise developing countries from expanding their ruminant industries. That is very much against the principles of the Paris Agreement and indeed all international climate agreements
Is there a comparison between natural degradation of a kg of grass dry matter – that is, rotting on the ground or burning, vs consumption by a ruminant.
The analysis often seems to start part way through the cycle.
If grass decomposes in the presence of oxygen (aerobic) then I would expect the products to be carbon dioxide and water. But if it is anaerobic then I would expect the main product to be methane.
That is right but it doesn’t matter what it breaks down to as it was recently removed from the atmosphere through photosynthesis. Even if it does end up as methane, that will break down to CO2 within 10-15 years.
The main point though is that it adds no new C to the atmosphere. This is because the C atom was removed from the atmosphere recently whereas fossil fuel derived C was removed from the atmosphere many millions of years ago.
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Why is it that we seldom (never?) see commentary on the Biogenic Carbon Cycle in the ruminant methane arguments?
If ruminant methane is simply a combination of naturally occurring elements and a result of sequestration of atmospheric carbon by (mostly) pasture, then where’s the argument?
The only way NZ is going to reduce methane production to the levels this government demands is to reduce ruminant numbers.
This makes no economic sense, but is makes NZ look great on the world stage!
Really enjoy your Posts.
Cheers, Trev Green