As Irish farmers take to the streets to protest against the high greenhouse gas (GHG) emission reduction targets for agriculture to meet the Paris Agreement, it is an opportune time to talk to a farmer who claims to have reduced the emissions on his farm by a notable 40 per cent.
Billy O'Kane returned from his job as a vet in the Yorkshire dales to run the family farm in Co Antrim in 2002 and bought 200 cattle from the American Stabiliser breed.
"I bought them because they are more profitable. They are a scientifically developed hybrid animal that eats less, grows faster and is sent to the factory younger," says O'Kane who now runs the breeding group for Stabiliser cattle in Northern Ireland.
Changing to this breed of cattle for beef production has been the single biggest factor in cutting emissions on his farm. As well as opting for this particular breed of cattle, O'Kane has reduced GHGs by reducing fertiliser inputs by half by introducing nitrogen-fixing clover in his grasslands and using low-emissions slurry spreading. These measures are also endorsed in the new initiative, Signpost Programme – Farmers for Climate Action, introduced by the agricultural advisory body Teagasc.
However, O'Kane has gone one step further by carrying out a study of the carbon outputs and carbon inputs on his farm. He drew on the UK Stabiliser Cattle Company's figures for carbon or GHG outputs. These combine methane from animals themselves with GHG from animal feeds, fertilisers and transport emissions. They were calculated by the accredited environmental performance assessment wing, E-CO2 , of animal nutrition company Alltech, he explains.
To calculate the carbon inputs, O'Kane employed PhD student, Josh Thompson to calculate the carbon sequestration on his farm. This involved calculating the carbon captured each year in soils and grassland, woodland and hedges on his 500-acre farm.
“There is more carbon dioxide stored in soil than all the trees on the planet and the key is that soil can sequester carbon while still producing food if treated in the right way, “ says O’Kane, who is a firm advocate of the no-till or minimum-till approach to reseeding grasslands and growing crops.
“There is more carbon loss from ploughing than any other type of farming. The key is not to expose the carbon in the organic matter of the soil to oxygen by direct drilling. That way, the soil will regain its embedded carbon through photosynthesis into the leaves and roots of plants,” he says.
Hedgerows, as carbon sinks, need to be classified according to their height, width and age. “There are rules about when to cut hedgerows but there needs to be rules about how much you can cut them back too.”
But here’s where the calculations get complex. O’Kane says that by using the current global warming potential (GWP) 100 accounting system, his farm is “only half way there to becoming carbon neutral”. However, if instead the newer GWP * accounting system, which calculates methane emissions differently, is applied, his farm would be carbon neutral now.
The crux of this issue is how methane emissions are calculated, which is obviously very significant when it comes to targets for agricultural emissions in national and global carbon emissions reductions.
Governments around the world currently use the GWP 100 accounting system but some climate scientists and the farming press argue that the GWP * accounting system is a more accurate and useful tool. The latter, which was developed by Myles Allen, professor of geosystem science at Oxford University with Frank Mitloehner, University of California at Davis, found that unlike carbon dioxide, methane increases global warming only if its emissions increase. If they remain stable, there are no further global warming effects and if methane emissions reduce, this has a cooling effect on the planet. However, if carbon dioxide emissions remain stable each year, they are still adding to global warming because of the cumulative effect of the GHG gathering in the atmosphere.
O’Kane, who will present a paper based on the results of his farm study at the British Cattle Breeders Club conference in January, agrees that reducing methane can be part of the solution to solving climate change. However, he argues that methane emissions from agriculture are not a cause of the problem.
"A 2015 study by the Smithsonian Institute in Washington DC, and the University of New Mexico explored the influence of ancient and historic megaherbivore expirations on the global methane budget found that 120,000 years ago the animals on the planet emitted 138.5 million tonnes of methane annually compared to 147.5 million tonnes annually today, which is a rise of 6 per cent," notes O'Kane, who contends that ruminant enteric methane production is really a very small contributor to global warming.
However, the American National Oceanic and Atmospheric Administration has stated atmospheric methane concentrations continue to rise from various sources including livestock. And Prof John Sweeney, emeritus professor of meteorology from Maynooth University, adds: "GWP* has advantages over GWP 100 in assessing compliance with temperature goals of the Paris Agreement but the Paris Agreement and the EU Green Deal and the UNFCCC reporting is defined only in terms of GWP 100. Any alternative would require 195 countries to agree."
O'Kane says he understands the argument that reducing methane levels can be an easier gain than reducing other gases because methane stays in the atmosphere for only about 12 years compared with thousands of years for carbon dioxide. Yet, like many farmers, he believes Ireland's grass-fed livestock is recognised as having a lower carbon footprint than farming in places such as Brazil. Ultimately, he says, a vaccine to reduce methane emitted from cattle may be a longer-term solution but, like methane-reducing supplements, this is still at the research stage.
O’Kane also insists producing beef is necessary to feed an increasing world population. “Only one third of the agricultural land on the earth can grow human-edible crops, so ruminants will always to be the only way to convert the herbaceous growth of the other two-thirds into human-digestible food,” he says. He does agree that if world population grows, then food animal numbers should not grow further and the increased food requirement should come predominantly from plants grown in a carbon-efficient manner.
“As a beef farmer working with the Stabiliser system, my part of the jigsaw is to demonstrate that the proven 40 per cent carbon saving per kilogram of meat in our system would allow our sector of farming to produce the same amount of human food with a 40 per cent reduction in carbon with no added costs.”
Ireland’s agricultural emissions
Unfortunately for Irish farmers, agriculture accounts for about 35 per cent of our national GHG emissions which represents the highest share of emissions from agriculture in Europe (the GHG emissions from agriculture in the UK are about 10 per cent). Of these agricultural GHG, methane emitted directly from the animals represents about 65 per cent, nitrous oxide from spreading fertilisers and slurry accounts for about 30 per cent and carbon dioxide accounts for about 5 per cent.
The fact that methane is deemed to be the second most potent GHG makes the situation for farmers even more demanding. The contribution of methane to global warming is estimated to be at least 25 times that of carbon dioxide over a 100-year period. And while methane only persists in the atmosphere for between eight and 12 years (after which it is broken down into carbon dioxide and water), it traps radiation more efficiently than carbon dioxide making it more potent over a shorter period.
And because methane has such as short half-life in the atmosphere, it is one of the gases which could be reduced more quickly. In Ireland, this means reducing methane emissions from agriculture.
Methane is also emitted from fossil fuel development and use, decay of organic matter in wetlands and forest fires. In June, US president Joe Biden signed a Bill to reinstate Obama-era rules to reduce methane pollution from the oil and gas industry.
The global methane budget combines national and international data on all possible sources of methane (numbers and sizes of cattle herds, sizes and locations of paddy fields, inventories of fossil flue operations, etc) and combines them to estimate how much methane each type of source emits. It found roughly speaking, fossil fuels and agriculture account for a third, with the remainder coming from emissions from cars, fires, landfills and wastewater processing. The US and the EU have recently pledged to cut methane emissions by 30 per cent by 2030.
