Technology that cuts methane output from cattle should be prioritised over “draconian” cuts in herd sizes or dietary changes, a US-based agriculture expert has told an Oireachtas committee.
As tensions mount over the sector’s ultimate contribution to greenhouse gas cuts, Frank Mitloehner at the University of California said efficiencies introduced in the US state, in collaboration with farmers, had cut 30 per cent of methane emissions over five years.
“We are formulating real workable solutions to a problem many believe can only be tackled through draconian herd size reductions and dietary changes,” Dr Mitloehner told an Agriculture committee hearing on Wednesday, saying such solutions could be tailored to Ireland. California’s dairy herd is comparable in size.
“Reducing herd size isn’t a practical solution, especially in countries like Ireland where farmers are very efficient producers,” Dr Mitloehner said, echoing an argument repeatedly put forward by Irish farmers.
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Any consequent displacement of production to less efficient countries, a phenomenon known as leakage, could “well lead to a spike and not a reduction in global greenhouse gas emissions”, he said.
A Department of Agriculture official later told the committee there was no discussion of a forced cull.
Wednesday’s hearing heard from several climate scientists. In the overall context of greenhouse gasses, some time was given to addressing the comparative threat of methane and carbon dioxide (CO2), and of biogenic methane, which is produced by livestock, and fossil methane produced by mining and fracking.
“Don’t let a methane discussion disabuse you of the notion … that we must reduce CO2 to net zero, that is the absolute imperative,” said Prof Peter Thorne, a climatologist at Maynooth University.
He compared methane to an electric heater that could be turned off quickly, and CO2 to a storage heater that stays warm — methane can be reduced far more quickly.
“If farmers were successful in getting to net-zero we would still miss our 51 per cent [carbon] reduction target because two-thirds of our emissions arise from the non-agricultural sectors,” he said, re-emphasising the need for just transition.
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The major greenhouse gasses are CO2, nitrous oxide (N2O) and methane (CH4). Prof Barry McMullen of Dublin City University said some technical and scientific issues had arisen in assessing the temperature impacts from the different gases, “particularly when they are combined into a single aggregate ‘carbon’ budget for policy purposes”, as is the case in Ireland.
Prof Myles Allen, a climate change expert at Oxford University, stressed the need to measure how each gas individually contributed to the overall heating of the atmosphere.
“We are still using this old … metric of CO2 equivalent emissions which doesn’t actually reflect the impact of methane emissions on global temperature,” he said.
While explaining that any future increase in herd sizes would have a very significant warming impact, Prof Allen said the methane released from mining would be of greater consequence.
Appealing for perspective, he said “even if we were to eliminate methane emissions from the entire ruminant herd worldwide we would [only] shave a few hundredths of a degree off global temperatures … that is [equivalent of] a few years of fossil-fuelled warming”.
With negotiations ongoing as to what level of emissions cuts the agricultural sector would be expected to deliver, there was some frustration among TDs and Senators as to what it would mean in real terms to farmers.
“This is what we need to know,” said Roscommon-Galway Independent TD Michael Fitzmaurice of explaining cuts in percentage terms to constituents. “We are working blindfolded at the moment and when we talk to people they are worried out there.”
