No favour from farmers at the idea of slashing stock to cut greenhouse gases.

LISTEN ABOVE: Anders Crofoot of Federated Farmers spoke to Rachel Smalley

UK consultants commissioned in a New Zealand cross party report say more than a third of pastural stocks would need to go.

That's if we're to bring our emissions to zero, by the end of the century.

But Federated Farmers climate change spokesman Anders Crofoot told Rachel Smalley it would come at other costs.

"At the present point in time it's not particularly feasible, from the point of view that slashing stock numbers basically means slashing income. Most people wouldn't be to happy being handed a 35 percent salary cut."

Mr Crofoot said milk production now is already using 20 percent less gasses than it was in 1990.

Vivid Economics managing director John Ward said if New Zealand wants its net emissions to hit zero by the second half of this century, it must make fundamental changes to its agricultural sector.

That means changing agriculture types and the use of land.

"So we'd be looking at a shift away from pastural agriculture towards a combination of horticulture, crops and forestry."

He said changes are required across all sectors of the economy and will have to be significant.

"In the energy sector, in terms of electrifying the transport fleet and doing that relatively quickly. In terms of increasing the amount of electricity produced for heat and then of course lots of the pastural agricultural sector as well."