One of New Zealand's biggest dairy lobby groups is calling for the Government to make major changes to its Zero Carbon legislation.
But Forest and Bird has dismissed DairyNZ's concerns and said dairying in New Zealand needs to change.
Speaking to MPs at the Environment select committee this morning, DairyNZ chief executive Tim Mackle warned that the bill as it stands could reduce dairy farmers' profits by between 33 and 42 per cent.
The legislation, unveiled in May, aims for all greenhouse emissions – aside from biogenic methane – to be reduced to net zero by 2050.
It commits to reducing gross emissions of biogenic methane to between 24-47 per cent below the 2017 levels, by 2050.
That 47 per cent level is what DairyNZ is taking issue with.
Mackle told MPs that if this became law, dairy farmers' total profit could reduce by 33-42 per cent across the 2030-2050 period.
"This is a substantial loss of income and is more than 10 times higher than the cost of $2500 per farm estimated in the Government's analysis. The impact for rural communities and the wider economy could be huge."
He said DairyNZ supported what the bill was trying to do and that farms wanted to "come along for the ride" but 47 per cent was far too high.
"This will be a real challenge for our sector, but we are up for it."
Mackle wants the Government to commit to a 24 per cent target.
But Forest and Bird chief executive, and former Green MP, Kevin Hague, said New Zealand "cannot afford to go easy on methane".
"If we imagine that we are going to hit any of these targets without making significant land-use changes, we're kidding ourselves."
He was critical of DairyNZ and said its submission was assuming that dairying in New Zealand would continue the way it has, far into the future.
He said that cannot be the case.
Hague called for the Government to adopt the 47 per cent methane reduction target.
DairyNZ is not the only organisation to question the cost of the Zero Carbon legislation.
The bill's regulatory impact statement (RIS) revealed that New Zealand's economy could miss out on up to $50 billion worth of economic growth because of the Zero Carbon Bill.
The RIS, written by officials at the Ministry for the Environment, reveals that New Zealand's economy will grow to $522 billion by 2050 if the zero-carbon legislation is not adopted and the status quo is maintained.
However, if the legislation does come into force – as it is expected to later this year – the RIS showed New Zealand's GDP in 2050 will be between $472 billion and $476 billion.
That is a difference of $45 to $49 billion.