The way in which methane emissions are calculated needs to change after 2030, according to Dr. Laurence Shalloo of Teagasc.
The head of the Animal and Grassland Research and Innovation programme made the comments at a meeting of the Carbon Removals Action Group (CRAG) in Co. Kerry last night (Thursday, November 17).
Ireland is on a legally-binding path to net-zero emissions by no later than 2050, and to a 51% reduction in emissions by the end of this decade.
The government has said that by 2030 the Irish agriculture sector must slash emissions by 25%.
“Can we get to 25%? Who knows. But we need to start on that journey now to start reducing our emissions,” Dr. Shalloo said.
He said that measures such as lower chemical nitrogen (N), increased use of protected urea and the reduced slaughter age of cattle must be implemented at farm level.
“The roadmap is set between now and 2030; that 25% [emissions reduction] target is set into legislation, set into Irish law.
“Post-2030, we talk about climate neutrality. How we get there isn’t set, so that’s really strongly up for debate and that’s important.
“When we talk about how we count methane between now and 2030 at a national level that’s set in legislation, but after 2030 it’s not set so we really need to start thinking about how we should count this post-2030.
“Climate neutrality is where we have to be by 2050, but we think that when we look at these numbers that maybe its possible to get there a lot earlier than 2050.
“Maybe it’s possible to get there by 2035, once we do the calculations right,” he told the meeting.
Methane
“The first and most important thing is to define what climate neutrality is. For me, it’s temperature stablisation. So that agriculture would not be contributing to increased warming in the atmosphere,” Dr. Shalloo said.
“We have to also accept that there is a certain amount of warming in the atmosphere from agriculture and by achieving stablisation or not contributing to additional warming, if we get to that point, we’re not taking out that historic warming.
“As long as we are not increasing the concentration of methane in the atmosphere, using a certain metric, we’re not contributing to increased warming,” he said.
Currently, scientists commonly measure greenhouse gases (GHG) in terms of their carbon dioxide (CO2) equivalence (CO2e). Although methane is a more damaging gas, with around 28 times the warming effect of CO2, its lifespan is only a fraction of that of CO2.
When CO2 accumulates in the atmosphere, it takes more than 1,000 years to dissipate, methane takes just 12 years, making it essentially a cyclical gas.
Shalloo explained that the global warming potential of methane is currently counted using a model called GWP100, established by scientists in 1990, which does not reflect that the gas is gone after 12 years.
Shalloo and members of CRAG favour the adoption of the GWP* metric developed by climate change researcher at University of Oxford, Prof. Myles Allen.
He said that this will better account for the different physical behaviours of short and long-lived gases.
The United Nations’ Intergovernmental Panel on Climate Change (IPCC) has previously stated that the global warming effect of methane could be overestimated by as much as three or four times.
Ireland’s National Climate Change Council also accepts the GWP* calculation, according to Shalloo.
He said that agriculture could potentially be the first sector in the whole economy to be climate neutral from a temperature stablisation point of view by as soon as 2035 or 2040.
However, this depends on methane being counted “right”, he said.
Research
Shalloo told the meeting that the current carbon footprint of Irish milk is “very competitive”.
He said that feed additives are now available which reduce the methane emissions produced by grazing dairy cows by between 7-8%, but the impact is short-lived.
“What we need to do now is to get it working longer and maybe get a slow-released version that will have an effect over a longer period of time,” he said.
Shalloo added that “a huge amount of work is going on” by Teagasc researchers to determine the carbon sequestration potential in Irish soils.
This includes 30 research towers being placed on different soil types at various locations nationwide.
Information gathered from these towers will be used to develop a robust scientific model for Irish soils, potentially within the next three-and-a-half years.
“Why have we not put more of this in before now? I suppose the big thing was cost.
“That infrastructure investment is probably €4.5 million across the country. Until we had significant funding from the department [of agriculture] we couldn’t do it.
“If you look at the rest of Europe, if you look at the rest of the world, we probably have the densest network in the world now of towers. We’re going to catch up really quickly,” Shalloo said.