There needs to be at least a 30 per cent reduction in Agriculture emissions to meet targets, according to a member of the Climate Change Advisory Council.
A number of Fine Gael Ministers have said they believe targets can be met without reducing the number of cows in Ireland.
But speaking at the MacGill School, Professor John Fitzgerald says that's not the case:
"This is the one area where there's going to be a substantial loss of output and income. We're not going to make the meet our targets on less emissions in agriculture fall by 30 or 30% or more. That's an absolute minimum. For me farming controlling by 20% at lots of jobs and food processing sector, that is really difficult."