To reach the 2050 goals, 280,000ha of new pine trees being planted on public land. Photo: 123RF
The government's claim to be on track for net zero emissions by 2050 relies on private companies planting pine trees on hundreds of thousands of hectares of crown land, official modelling shows.
The coalition government says the country is on track for net zero by 2050, with Minister Simon Watts saying the coveted goal could be achieved as early as 2044.
The modelling underlying those claims has now been released, showing it would entail 280,000ha of new pine trees being planted on public land.
That is the equivalent of all the private farmland Beef + Lamb says has been converted to carbon farming since 2017.
Critics say it would amount to privatisation by stealth and ministers are wrong to think there is that much low value land to plant.
"I think they're dreaming if they think that that's the case," said Gary Taylor of the Environmental Defence Society.
"Would you plant the whole of Molesworth station in pine trees? Molesworth, which is New Zealand's largest farm, is only 160,000 hectares, so the numbers here are enormous."
Forest and Bird's Nicola Toki said carbon forestry would lock up public land forever.
"It is worrying if the government thinks planting pine trees is our climate salvation.
"It does feel a bit like flogging off the public conservation estate by stealth," she said.
The National Party has been clear that a key plank of its climate policy is allowing private companies to plant trees on what it deems low value Crown land.
The planting is slated to absorb more than 15 million tonnes of carbon dioxide between now and 2050 and is one of only a few big policies aimed at meeting the country's targets.
But the level of pine planting that might be entailed was not clear until now.
The economic modelling by the Ministry for Primary Industries (MPI) was released under the Official Information Act to climate policy expert Christina Hood. She said she wanted to understand how the forestry numbers added up toward New Zealand's climate targets.
"The Emissions Reduction Plan released in December was a bit vague about how much extra planting would be needed to close the emissions gap - it turns out it's far higher than I'd expected," she said.
Climate Change Minister Simon Watts said modelling was inherently uncertain and real planting levels would depend on a range of factors, including land characteristics.
He said no decisions had been made on the mix of species planted - but there was "promising" interest from the market in planting both pines and native trees.
Asked if 280,000 hectares of pine on publicly-owned land would be a good outcome, he said planting exotic trees for logs and/or carbon sequestration "could be a more efficient use" of unproductive land.
However the modelling shows if planting levels do fall short of the assumptions, New Zealand would be off track for net zero by potentially millions of tonnes.
Watts says the government will adjust, if necessary.
How many trees?
Getting to net zero for long-lived gases is enshrined in New Zealand law and the country's international obligations.
The "long lived gases" mentioned in the net zero target are carbon dioxide and nitrous oxide - a long-lived greenhouse gas produced by farming. It doesn't include methane, a short-lived gas which is also mainly from farming.
The MPI modelling of the tree planting underpinned government projections in December, showing New Zealand was on track for net zero in 2050.
Both Watts and Prime Minister Christopher Luxon have cited the net zero projections when criticised about climate change.
The modelling shows these trees on crown land sucking in around 5 million tonnes of carbon dioxide in 2050, almost exactly what is needed to offset farming's nitrous oxide emissions.
The reason it assumes most of the trees will be pine, is that pine is cheaper to plant than native trees and generates carbon credits more quickly.
Generating a return is important, because the government hasn't allocated any funding to the policy.
In all, to get the necessary carbon savings, MPI assumed 330,000 hectares of trees would be planted on Crown land, 280,000 hectares of them pine.
Of those pine trees, 230,000 hectares would be permanent carbon forests (not for harvesting) with another 50,000 hectares dedicated permanently to logging.
That would be enough to achieve net zero in 2050.
If real planting turns out to be less, the government will face a climate hole.
Low or high value?
Toki said the estimates were just modelling and unlikely to be realistic, meaning the government needed a climate backup plan.
She suggested pest control in native forests, to boost carbon storage.
Both she and Taylor said any planting of conservation land should involve native trees.
A desktop survey for the government identified some 760,000 hectares of Crown land that might be suitable for planting. That was based on land that wasn't in a National Park, or already forested.
The government believes a lot of this land is low value, and ripe for other uses.
But the land was not screened for conservation or farming value before the government put out a request for expressions of interest.
Taylor said the land was mostly either high country farmland, or important conservation land that had been in a "holding pen" awaiting classification.
Meanwhile, Toki said a recent review of West Coast conservation land had found just 0.01 per cent was sufficiently low value that it could be disposed of.
She said much of the conservation land the government was talking about was visually indistinguishable from National Parks - and sometimes right next door to them.
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