But an expert says that the report ignores a significant increase in real-world atmospheric methane, as well as using one modelling scenario that would exceed a target of 2°C of warming.

Methane is a short-lived but potent greenhouse gas and New Zealand produces a disproportionate amount of it compared to other countries.

According to the Ministry for the Environment, the agriculture sector contributes 50% of New Zealand’s gross emissions, with about three-quarters of that coming from biogenic methane emitted by livestock – mostly from the dairy herd.

The industry is under pressure to make reductions, with a target of reducing biogenic methane emissions by 10% by 2030, relative to 2017 levels, and 24 to 47% lower by 2050, while the government is investing more than $380 million researching ways to reduce emissions without significantly reducing the herd.

Federated Farmers, Beef + Lamb, and DairyNZ commissioned the report, led by Myles Allen, who is a professor of Geosystem Science at the University of Oxford, director of the Oxford Net Zero Initiative, and a former Intergovernmental Panel on Climate Change (IPCC) lead author.

The report found that if other countries meet their existing emissions reduction commitments, then a 15% reduction in methane would see New Zealand methane contribute no additional warming from 2020 levels.

The report also notes that if countries significantly increased their current levels of ambition a reduction of up to 27% may be required – significantly less than the current methane reduction range of 24 to 47%.

Federated Farmers President Wayne Langford says the current methane reduction targets have been “a real point of contention” for most farmers, who feel they have been asked to go further and faster than needed.

“For years farmers have been told that we’re responsible for half of New Zealand’s ongoing emissions, but this report clearly shows that we’re not responsible for half of the ongoing warming – and warming is what we’re trying to prevent,” he says.

Report ignores real-world methane levels

However Martin Manning, adjunct professor at Victoria University School of Geography Environment and Earth Studies, says the research commissioned by the agriculture sector would need to be developed further before it could be the basis for any change in current national targets.

Manning was director of the Intergovernmental Panel on Climate Change (IPCC) Working Group Technical Support Unit that produced the Fourth Assessment Report on climate change. He was the founding director of Victoria University’s New Zealand Climate Change Research Institute and has also been an author and review editor for several of the major IPCC reports.

He says the report has an overly narrow focus, looking at just two future scenarios. One of the scenarios is aimed at keeping global warming close to a 1.5°C target – but reviews have shown this to be “very optimistic,” while Manning says the other scenario in the study is completely inconsistent with the 2°C target that is inherent to the Paris Agreement.

“Why is the more extensively studied, and still feasible, SSP126 scenario that is likely to keep below 2°C not being considered?” Manning asks.

He says the report infers that reducing food production in New Zealand would lead to production increasing in other countries, and assumes that consumption patterns won’t change. “This is in contrast to interdisciplinary studies that show sustainable development consistent with the Paris Agreement requires a wide range of structural changes, including in human diet.”

The scenarios also don’t take into account the huge rise in atmospheric methane in recent years. “Use of these scenarios is also becoming increasingly irrelevant for methane that has its atmospheric concentration rising at record rates when all scenarios for keeping below 2°C have it decreasing.”

The report uses a method of evaluating carbon dioxide equivalence that is more favourable for methane, “global warming potential*” or GWP*. “While use of GWP* to compare methane emissions with those for CO2 can be relevant in some circumstances, it can lead to an inherent bias towards preserving current emissions,” Manning says.

“More specifically and in contrast to the standard GWP metric, GWP* does not quantify the warming that would be avoided if a current emission did not take place.”

A reduction in the amount of warming should not be seen as “cooling,” as the report infers, Manning says. “Smaller emissions of methane still warm the climate, even if not by as much as larger emissions.”

Climate Commission reviewing emission reduction target

Grant Blackwell, Climate Change Commission chief scientist, says the Commission will consider the report as part of its review of emissions reduction targets. The Commission is required to review the target every five years, with the first review due next year.

“We’re reviewing and considering every piece of information we received, and will use it where appropriate to inform our analysis on whether Aotearoa New Zealand’s emissions reduction target should be changed,” Blackwell says.

Recommending a change to the target requires a two-step process for the Commission.

“First, we need to establish that there has been, or likely will be, a significant change in one or more of the factors the legislation says we must consider, such as significant new evidence or a new global context for change. Then we need to determine if that significant change justifies a change to the emissions reduction target,” Blackwell says.

“It’s possible that there could be several significant changes that act in opposite directions so effectively balance each other out. This analysis is what we’re working on now.”

Blackwell says the Commission’s advice is provided to help the government determine the best choice for Aotearoa New Zealand under current, and predicted, circumstances.

“We’ve always been clear that there is no one ‘right’ path to achieve the target – there are possible choices, each with consequences.”

The Commission will be consulting on this work in the first half of next year, with final advice delivered to the Minister of Climate Change by the end of 2024.

Greenhouse gas emissions have long been a vexed issue for farmers and the government, with the ‘He Waka Eke Noa’ government and industry partnership to regulate agricultural emissions floundering after years of negotiations.

The government recently announced farm-level emissions reporting now won’t start until the end of 2024, and emissions pricing won’t start until a year later – effectively giving farming a two-year reprieve from its emissions being included in the Emissions Trading Scheme (ETS).

However National has vowed to keep agricultural emissions out of the ETS if elected, and has said it would implement a separate pricing system for on-farm emissions by 2030 – effectively giving farmers an additional five years.