National Party leader Christopher Luxon says Tuesday's emissions announcement is a disgrace to New Zealand farmers who he says are already the most carbon efficient in the world.
The Government on Tuesday released what it called a "pragmatic proposal" to reduce agricultural emissions - including requiring farmers to pay levies on emissions from 2025.
Damien O'Connor, the Minister for Agriculture, said the proposed pricing system supported farmers to make decisions about what they do on their farms by incentivising emissions reductions and climate-friendly practices.
But Luxon said the Government needed to treat one of New Zealand's highest-earning sectors better and stop pushing them away.
The Government's consultation document on the proposal said total revenue from the agricultural sector could be "significantly affected" by the plan - with sheep and beef net revenue potentially dropping 24 percent.
"This is utterly unacceptable, what was announced yesterday," Luxon said of the proposal.
"What it's saying is one-fifth of our sheep and beef farmers will be gone by 2030 [and] a 5 percent reduction in our dairy farmers in that period of time," he told AM on Wednesday.
Luxon noted New Zealand fed 40 million people through the country's food production.
"[A lot of] that production will simply just go offshore to less carbon-efficient countries," he said.
Speaking to AM host Ryan Bridge, Luxon said such a reduction in the sheep and beef sector would have "huge flow-on effects" for New Zealand.
"The frustration is, we asked the sector to develop a strategy - we trust farmers, we back them, they get it out there… They had a solution that they introduced in May and the Government's gone away, noodled, come back with a whole bunch of builds on top of it and, as a result, one-fifth of our sheep and farmers are gone by 2030.
"It's a sector that employs 350,000 people across the country, feeds 40 million people across the world and generates a huge amount of our export earnings."
According to Luxon, "you just can't knock off a fifth of our sheep and beef farmers".
"We understand we have to price agricultural emissions and we ultimately have to reduce our emissions… [but] you can't support it in this form," Luxon said of the Government's proposal.
He said National would support an "industry-led solution" to reducing carbon emissions.
Luxon said the Government had made "its own" additions to the Emissions Reduction Plan released in May, which he described as "unpalatable".
"Now, we're going to have [a] fragmented industry consensus and, actually, the whole thing falls apart.
"We've got to get back to industry consensus and getting that industry joined up to what it thinks it needs to do."
O'Connor said New Zealand would continue producing high-value, high-quality products that produced a lower carbon footprint, under the Government's proposal.
"That's the space that we have to be - as a nation of food producers," he told AM.
"Kiwis and Kiwi farmers are some of the most adaptable, innovative people in the world - particularly when it comes to food production.
"The impact on dry stock farmers, we acknowledge is going to be more challenging than that of the dairy industry but there are many options for some of that land and we're seeing small plantings of forests for some areas - we maybe will see a little more beef and less sheep but I think, as we go through and identify sheep that are lower-emitting… we will see that the impacts of this price of agricultural emissions won't be what the model's predicted."
On Tuesday, Federated Farmers said the Government's plan would "rip the guts out of small-town New Zealand".