The head of the Irish Farmers' Association (IFA) says farmers 'will work' with the Government's new Climate Action Plan.
However Tim Cullinan warns this will mean enormous cost for the industry.
The plan has guideline sectoral targets all across the economy as part of efforts to ease global warming.
Agriculture has been set a reduction of between 22% and 30% between now and 2030.
There will be a reduction in chemical nitrogen and more targeted use of fertiliser, as well as improving the genetics of herds to reduce emissions and improve productivity.
The plan says farmers will be "incentivised" to make these changes, and there will be new income streams in areas such as the generation of renewable energy.
While there is no specific mention of reducing the national herd.
Mr Cullinan, who is attending the COP26 UN climate summit in Scotland, told The Hard Shoulder this was never going to happen.
"This is going to be extremely challenging, obviously, for farmers - farmers are very concerned around this.
"There has been an obsession recently with cutting the national herd, and as I've said on several occasions, there is no such thing.
"The animals in the country are owned by 120,000 or 130,000 farmers, each having 70 or 80 animals.
"There's a lot will have to be done here, farmers will work with this - but obviously there's going to be an enormous cost here as well.
"What I'm hearing out here at COP is, I spoke to an awful lot of farmers yesterday from right around the world... everybody is saying farmers are more than part of the solution.
"But governments around the world are not coming forward with a plan for farmers."
He says if Ireland does not produce food here, we will have to get it from elsewhere.
"And the other thing we need to remember here, in particular in Ireland and in Europe, we have one of the best places in the world for producing food.
"The grass-based system we have is the most efficient in the world from dairy and the fourth or fifth most efficient for producing beef.
"If we don't continue to produce the food here, obviously we're going to have carbon leakage - that will not do anything to help the environment.
"We are up for this challenge, but we need a plan from our Government - I've been consistently saying this".
'It's going to take time '
He says while there are options available to reduce carbon emissions, costing has to be paramount.
"If we look at it, reducing fertilsier below a threshold that produces grass is going to be a challenge - but we will adopt to that.
"We have the low-emission slurry systems, which makes the animal manure organic fertiliser far more available on land and we can achieve a lot there as well.
"Another area.... genetics will improve, and it has been shown already that different bovines produce less methane - so obviously that's going to take time to work that through the system.
"And obviously an awful lot of research work is being done around different additives that bovines can consume, and will help reduce emissions as well.
"There's a cost in all of this, and clearly now... the Government has to sit down - the Taoiseach and the Tánaiste, all of the Government.
"A whole of Government approach is needed around this immediately".
