Climate change researcher, Prof. Myles Allen is expected to propose changes in methane-emissions calculation, which could “defuse the perceived tension between climate policy and agricultural interests”.
Prof. Allen from the University of Oxford will address a special meeting of the Joint Oireachtas Committee on Agriculture, Food and the Marine (JOCAFM) tomorrow (Wednesday, July 20).
In a briefing note to the JOCAFM, Prof. Allen said Ireland should set a goal to stop any continued fossil fuel-use from causing global warming; and report the climate-warming impact of emissions.
While Prof. Allen and other climate researchers will discuss how methane emissions are being calculated in Ireland, a section of the meeting is dedicated to sectoral emissions ceilings.
Emissions calculation
The standard method used for characterising the impact of emissions on the climate, in terms of a carbon footprint or carbon dioxide (CO2) equivalent emissions, Prof. Allen said, does not reflect the impact of human activities on global temperatures.
A herd of 10 cows generates about 1t of methane/year, which, under standard carbon-footprint calculation, suggests that this is equivalent to 28t of CO2/year, according to Prof. Allen.
“Whereas, if (like the Irish average) that herd was built up over the last century, it is only causing an ongoing warming equivalent to about 8t of CO2/year, a factor of three to 4 times less than 28.
“But if the herd is increased by just one cow, that increase alone causes warming equivalent to an additional 13t of CO2/year over the next 20 years, and 0.8t of CO2/year thereafter,” he said in his briefing note.
A 3% reduction in emissions per decade would lead to no further warming caused by a herd, because the impact of the decline cancels the warming impact of the ongoing methane emissions, Prof. Allen said.
This could either be achieved by a gradual reduction in the head count, or by adding seaweed to fodder, for example, while any reduction faster than 3% would have the same impact on global temperature as active CO2 removal from the atmosphere, he added.
Outlining the negative consequences of treating methane emissions as CO2 equivalent, he said farmers have less incentive than they should to reduce methane emissions.