PM rules out slashing herd numbers to meet emissions targets

Prime Minister Bill English says "we're not setting out to slash agriculture" as a report released on Tuesday outlines reducing animal numbers by 35 percent as one option to cut emissions.

A cross party group of MPs commissioned London firm Vivid Economics to look at options to get New Zealand on track to the global commitment to reduce emissions to net zero under the Paris Agreement.

The "net zero" goal means neutralising human emissions through measures like planting trees or technological solutions that draw carbon from the air.

The report has outlined four bold scenarios for the Government to consider in policy decisions.

Under one scenario, New Zealand would reduce emissions of its economic activity through technological advances, including a vaccine to reduce methane from agriculture.

This would be accompanied by a "structural shift away from pastoral agriculture", slashing stock numbers by 20-35 per cent and supporting more diverse land use through horticulture, crops and planting another 1 million hectares of trees.

But Mr Bill English said on Tuesday that "wouldn't be good for New Zealand".

"We're not setting out to slash agriculture and destroy those communities," he said.

"It's easy for people to say that.

"It'd be bad for our economy. We are working alongside these communities and the farmers around ensuring they are investing in dealing with the impact."

Mr English says the economy is "already diversifying quite significantly".

"I think we learnt that when the dairy prices were down that the economy is not totally dependent on it at all."

In a second scenario, New Zealand would grow its renewable power by 75 percent, electrify 85 percent of its light duty passenger vehicle fleet and speed up targeted breeding, new feeding regimes and nitrogen and methane inhibitors.

However, livestock numbers would remain the same and forestry would expand by 0.5 million hectares.

The report says this scenario "is not sufficiently ambitious" to get New Zealand on track to net zero emissions.

Under a third scenario, global technological development doesn't progress rapidly enough so forests are required to expand by 1.6 million hectares. The report says this changed land use might mean a difficult transition for rural communities, as well as a lost opportunity to reintroduce native habitat.

The report authors conclude reducing New Zealand's emissions will mean substantial change to energy supply and use, including moving towards a 100 percent renewables grid and electrifying the passenger vehicle fleet.

"It is possible for New Zealand to move onto a pathway consistent with domestic net zero emissions in the second half of the century, but only if it alters its land-use patterns."

The Green party is calling the report a "political breakthrough".

"For the first time there is a shared understanding across all parties in Parliament about the nature of the challenge in front of us," co-leader James Shaw says.

"This report has shown it's entirely possible for New Zealand to have a prosperous future that doesn't come at the cost of our environment."

Sustainable Business Council Executive Director Abbie Reynolds says the fact that the report is cross-party is an important precedent that gives business confidence of collective action toward meeting New Zealand's Paris commitments.

"Our members have identified climate change as a priority and are ready to work with government on the transition to a low carbon economy," Ms Reynolds says.