As the methane heat is turned up, is it time for measurement rethink?

Eric Barker, 20/10/2022

AS THE environmental impact of livestock-related methane emissions becomes a hot topic in the global climate change debate, calls are growing for wider recognition of more relevant ways of representing the industry’s footprint.

Livestock have been front and centre of climate politics in recent weeks, as the Federal Government signs onto the Global Methane Pledge and other countries, including New Zealand, put restrictive legislation on livestock producers.

While many countries are moving on livestock emissions and the industry is putting in its own measures, like the carbon neutral by 2030 target, the way livestock emissions are accounted for is still creating some concern among the science community.

The current metric used to represent emissions across most industries is called GWP 100 (Global Warming Potential), which aims to put all gases on a common scale of “CO2 equivalence” over a 100-year time horizon.

But CSIRO principal research scientist, Agriculture and Food, Dr Brad Ridoutt said GWP 100 was not the only way of aggregating emissions and may not necessarily be the most relevant way for the livestock industry to report emissions and direct climate action.

“Methane emissions have a relatively short-term impact on the climate, unlike CO2 and other longer-lived greenhouse gases (GHG),” he said.

Dr Ridoutt said the main scientific body, the Intergovernmental Panel on Climate Change (IPCC), had made the distinction between the different gases.

He pointed to this quote “Stabilizing the climate will require strong, rapid, and sustained reductions in greenhouse gas emissions, and reaching net zero CO2 emissions. Limiting other greenhouse gases and air pollutants, especially methane, could have benefits both for health and the climate.”

Dr Brad Ridoutt

Several other metrics have been developed to better represent livestock emissions – the most well-known one is an Oxford University method called GWP star. Dr Ridoutt has also been part of the development of a methodology called the radiative forcing footprint (RF).

“With GWP star, it looks at whether methane emissions are increasing or decreasing over time. However, livestock emissions can jump up and down like a yoyo, with seasonal conditions and herds expanding and contracting. This creates some issues with GWP star because it can be hard to discern a steady rate of change,” he said.

“The radiative forcing footprint has some similarities with GWP star but is simpler.

“GHG emissions contribute to global warming by increasing radiative forcing. The RF footprint aggregates RF from current emissions with the residual RF from historical emissions. This way, we see whether the industry is increasing its overall footprint or decreasing it. When RF is stabilized, the industry might be considered ‘climate neutral’, i.e., no longer adding to further climate change. This is what the Paris Agreement is all about, stabilizing the climate.

“This is what I have shown with the sheep meat industry, this industry is no longer adding to additional climate change.”

How the livestock industry’s emissions are reported

All sectors, including livestock, have their emissions reported annually in a Federal Government document called the National Greenhouse Gas Inventory. MLA releases its own GHG footprint, which includes similar information to the NGGI.

Dr Ridoutt suggests the red meat industry take on the use of a metric like the RF footprint.

“They should be using the metric that is relevant to them and taking a proactive approach, because it gives better information in regard to the goal of climate stabilisation. The industry can voluntarily report whatever it wants, provided it is science based and factual.”

In response, MLA CN30 manager Dr Margaret Jewell said investment was currently underway, via Dr Ridoutt, to enable the use of such metrics, with results are expected towards the end of this year.

“In Australia we’re aiming to use all of the metrics we can, because we think it is important to report really transparently about the impact of livestock on the climate. It is also important so we can set appropriate policy and mitigations,” Dr Jewell said.

Shift away from GWP 100

Dr Ridoutt said the universal use of GWP 100 was not warranted. The results can be difficult to interpret when there are substantial short-term emissions like methane.

“We need to look at what we are trying to achieve and under the Paris Agreement, it is about keeping the global average temperature below a 2-degree increase – ambitiously 1.5 degrees,” he said.

“All through the IPCC reports they don’t prescribe any metric and they caution against the use of any particular metric, because it might not answer the question at hand.”

Dr Ridoutt said reducing methane was important because it can create scope for the industry to grow without increasing its RF footprint.

Along Dr Ridoutt, several respected scientists, including University of California Davis professor Frank Mitloehner and Oxford University professor Myles Allen, have been pushing for more transparent measurement of livestock emissions for years.

Prof Allen told a recent inquiry, held by the Irish Government, that it could be leading the world by including metrics, like GWP star, in its greenhouse gas account, alongside GWP100 measurement.

“We can fix the problem of not reporting warming impact tomorrow and you can calculate it on a farm-by-farm level,” he said.

“If you were to do this, it would be interesting for Irish farmers because they would discover the things they can do to reduce global temperatures. This issue with reporting is not a problem we need to have.”

Industry aims for carbon neutral

While red meat industry is pushing ahead on its plans to become carbon neutral by 2030, MLA managing director Jason Strong said the development of metrics like RF and GWP star was important to the industry.

“Climate neutrality is one of those little bonuses on the way to carbon neutral – it is really important because so many of the global commitments, like the Paris agreement, are based on warming” Mr Strong said.

“Methodologies like RF and GWP star are very important, there is plenty of people focusing on them and we will certainly stay across them. But the CN30 target is one that we will keep putting our efforts into and making sure we have the tools and suite of solutions to allow people to do that.

“We want to be in a position where we can maintain a larger herd and flock in a sustainable way.”

Government not adopting other methodologies

Beef Central contacted minister for energy and climate change Chris Bowen and asked if the government was considering putting additional information on livestock emissions in the NGGI – using metrics like RF and GWP star. A spokesperson for the minister said it was not in the plans.

“Australia is required to use the GWP-100 metric for reporting under the Paris Agreement. The GWP star method is not currently recognised in international inventory reporting rules,” he said.

  • More on the Global Methane Pledge here


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  1. Sandy Walker, 31/10/2022

    Keep up the good work..

  2. John Wyld, 28/10/2022

    The missing fact is always the fuel that drives methane production. For runinants it is grass, for transport and power generation etc., it is fossil fuel.
    They cannot be compared. Grass absorbs CO2 from the air, which is then recycled by the cow, whereas fossil fuel ADDS to the atmosphere.
    Ruminants are part of a natural cycle, and not a problem.
    However, our reaction to the constant attacks, driven by a range of agendas, has fallen short. We need to lift our game before it is too late.

  3. David Stanley Lovelock, 24/10/2022

    Great to see recognition of cattle , grass , methane being part of the natural carbon cycle . Methane brakes down in the air and is nearly all gone in 12 years but of course starts to break down as soon as released and half of molecules released are gone in 2 or 3 years – referred to as its half-life . Example 8 molecules today ,only 4 left in 2 or 3 years , only 2 left after another 2 or 3 years etc

  4. mick alexander, 23/10/2022

    Please lets get some actual facts about methane and stop with the so called modelling of a theory. Now science facts are: Cattle expel methane (CH4) and other gases (yes); Photo-oxidation reaction produces the hydroxyl radical (-OH) in our healthy pastures (yes); the naturally produced hydroxyl radical degrades methane and other gases produced immediately (yes); The hydroxyl radical is created at ground level by a process that splits the transpiring water molecule into the hydroxyl radical (yes); Hydroxyl is produced at 100 times/ha more volume than the methane ever expelled by the cows in the paddock (yes); Farmers need to assess the volume of hydroxyl produced and invoice the government for the difference (yes); regenerative farmers with healthy growing pastures can never be charged for a methane tax; About time our universities, MLA and industry bodies got on board with the science or quit their jobs.

  5. John Schultz, 21/10/2022

    I read somewhere that methane, emitted by livestock, is acted on by something called the “diative?” effect, which reduces/negates the methane from entering the atmosphere. Also, this would not happen in feedlot conditions.

  6. Richard Rains, 21/10/2022

    Eric, I am sure this is interesting BUT I am afraid I don’t understand a word of it!
    This statement sounds good BUT, I have no idea what it means……..”sheep meat industry no longer adding to additional climate change.” Can you please explain ‘not adding to additional’????
    Also, can you earn carbon credits for growing grass?? or only trees etc.

    Hi Richard, it basically means not adding any more to global warming, or climate change, than what has happened historically or naturally. Methane emissions from ruminant animals, like cattle and sheep, have been cycling through the atmosphere for centuries – they are belched out and they break down after about 12 years. Those emissions are believed to contribute to global warming while they are in the atmosphere. So, if the sheepmeat industry was to push out more emissions today than it was 12 years ago it would be “adding to additional climate change”, because it would be putting more emissions into the atmosphere than what is breaking down. However, it is not adding more to the cycle so it is not contributing more to climate change than what is naturally happening.

    With the grass and carbon credits, soil carbon is the most common way of earning carbon credits for growing grass. We had this interesting column from Precision Pastures recently

    Hope this helps Richard. Eric

    • Richard Rains, 21/10/2022

      Eric, sorry if my initial comments were a little harsh. By no means was it meant as a shot at you personally….it was my frustration for how complex and difficult to understand, this whole climate measurement business is. We need people like you to keep us across the issues and I appreciate your efforts to keep us across the issues. Thanks for your further explanation.

      All good Richard, happy to give further explanation where I can and I certainly understand your frustration with the complexity of the subject. Did not see this as a harsh comment and keen to have more dialogue like this in the future. Eric

      • mick alexander, 19/12/2022

        Hi Richard and Eric, The confusion comes from the fact that these models are all only discussing bits of the whole in isolation. One of the bits missing is that the Hydroxyl Ion is produced at ground level from transpiring pastures during daylight hours. this hydroxyl ion immediately degrades the methane (not in 7-12 years) but immediately as Hydroxyl is very volatile attaching to the nearest gas and thereby degrading it. Cow methane never makes it to the troposphere except maybe from feedlots. Cows, healthy regenerative pastures and even actively growing crops would all be methane neutral as they are aiding in the production of hydroxyl.

  7. David Tannock, 20/10/2022

    So there we have it, Minister Bowen and his Clmate Change minions are to unswervingly follow the parameters of the Parish Accord, refusing to look at progress in science which may disprove the theoretical rhetoric or provide a more accurate path of measuring Methane omissions. So much for “the science” driving Climate Change which the world’s populations have had rammed down their throats. This is just another case of cherry picking the science to suit the argument or not wanting to hear the truth.

  8. Peter Dunn, 20/10/2022

    One has to agree with part of the title, ‘it is time for a rethink’. A rethink is well overdue actually, but not for measurement.
    Today, the media reported that China announced a 10% increase in the use of coal for energy, confirming that the biggest emitter in the world is going to get even bigger, sweeping aside Xi’s pretence about concern for climate change.
    Consequently, nothing that Australia, or any similarly lower end emitting nation does, to attempt lessen the man-made impact on the climate, will be barely measurable, and indeed will be of absolutely no significant value.
    So why then do we ignore reality and keep trying? Why are we focussing our efforts on struggling industries in Australia, and by our silence and inaction allow the major emitters, of which China is ahead by a mile, to go unchallenged.
    Why are we funding research which can only produce meaningless results in a global context, even though it may cause some to feel virtuous, and possibly also keep them in a job? Meanwhile, meaningful research is going begging.
    When will any of our leaders, be they in Government, industry, research or elsewhere, call a stop to this foolishness and encourage all industry efforts, all funding, all political strategies and all national influence be directed outside of Australia and towards reining in the major emitters. When will this responsibility be accepted and such leadership be demonstrated? When?

  9. John Bavea, 20/10/2022

    I have noted that the Carbon discussion revolves around the question of what Carbon equivalents cattle emit.

    Little, if any credit or recognition has been given to what Carbon they consume. I would have thought that the laws of physics would suggest that what they emit, could not exceed what was consumed.

    If this is the case cattle should be recognised as being Carbon neutral.

    One can only hope that new metrics, that consider both sides of the ledger gain the consideration they deserve.

    Hi John, this is where the whole climate neutral idea comes in. Has been a discussion for a while Editor

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