The Financial Times ran a front page story yesterday, saying that climate scientists are accusing New Zealand politicians of trying to cover up livestock emissions using an “accounting trick” to back the sheep and cattle industry, and warning their support for methane-emitting livestock could undermine global efforts to fight climate change.

In the open letter, 26 scientists from around the world have warned that aligning New Zealand’s new methane targets with “no additional warming” risks setting a dangerous precedent.

The independent Climate Change Commission has advised that the 2050 biogenic methane target should be strengthened to a 35-47% reduction on 2017 levels, which is around the middle of the current 24-47% legislated range, saying a minimum 35% biogenic methane reduction in 2050 is achievable and affordable.

However, the government set up a separate independent methane review panel last year, in response to agriculture industry lobbying, which showed that New Zealand’s methane emissions reductions, consistent with “no additional warming” since 2017, could vary between 0% and 24% depending on greenhouse gas emissions in the rest of the world – significantly lower than the commission’s advice.

The review was controversial, with the Climate Change Commission rejecting the basis for the review of the targets and warning that changes could lead to higher emissions and increased warming, while the Parliamentary Commissioner for the Environment criticised the review as a waste of money, warning the government’s proposed approach could lock in a higher level of agricultural emissions as “a right” indefinitely.

The government is expected to announce new methane targets later this year.

Meanwhile, farming lobby groups have recently ramped up opposition to even the lower 24% methane target, with Federated Farmers saying they are ready to “go into battle” with the government over the issue, and questioning whether there should even be a methane target at all.

Lobby group Groundswell has even launched a billboard campaign against international climate targets, claiming: “the Paris Agreement is destroying us.”

The scientists’ open letter now warns Luxon against adopting a new biogenic methane target based on the goal of achieving “no additional warming”.

“Methane has roughly 80 times the heating effect of carbon dioxide over a 20-year period and an atmospheric life of around 12 years compared to hundreds of years for carbon dioxide. Because of these properties, the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment report concludes that swift reductions in methane pollution are a key component of actions to limit warming in line with the long-term temperature goal of the Paris agreement, which aims to avoid potentially catastrophic tipping points,” the letter says.

Paul Behrens, global professor of environmental change at Oxford University and a signatory of the letter, told the UK-based Financial Times that a “no additional warming” target could allow emissions to remain flat rather than decline, potentially enabling high levels of methane emissions and climate damage to continue. “It’s like saying ‘I’m pouring 100 barrels of pollution into this river, and it’s killing life. If I then go and pour just 90 barrels, then I should get credited for that.’”

Among the 26 signatories are just three New Zealand-based scientists, including climate scientists and former IPCC lead authors James Renwick, also a former Climate Change Commissioner, and Martin Manning, founding director of the New Zealand Climate Change Research Institute at Victoria University of Wellington.

Political stunt

Climate scientist David Frame, who was part of the government’s independent methane review panel last year, thinks the open letter is a “weird political stunt.”

“Drew Shindell, the ostensible leader of the motley pack, doesn't seem to have penned any Open Letters in response to his own President threatening to leave the Paris Agreement entirely, so I don't think you should see this as any sort of principled defence of climate policy - it's an attempt to intimidate a small country in its former colonial overlord's media: something that seems both very dated and very presumptuous.”

Frame, who is currently a University of Canterbury Physics professor, and former IPCC lead author and director of the New Zealand Climate Change Research Centre, says that only about half a dozen of the signatories are climate scientists as classically understood, publishing in climate science literature. “Most of them are ecologists or land sector people or from other disciplines.”

Referring to the Financial Times article, Frame says that calling GWP* an "accounting trick" is a flat out lie. “It's a superior way of comparing long- and short-lived emissions, if what you care about [is] the ability to simulate temperatures.”

“My guess is that they've been stimulated to do this by the Climate Change Commission, or maybe people close to it. Former Commissioner James Renwick is a signatory, for instance, and the main action the letter calls for is: ‘We call on the government to follow the guidance of its independent Climate Change Commission and deliver methane reductions that contribute to the goal of limiting global warming to 1.5 degrees, consistent with the purpose set out in New Zealand’s national climate change legislation.’

“In other words - trust the Commission. Don't think for yourselves. I think they are entirely wrong, not just in the silly claims they make about GWP*. Actually, the Paris Agreement doesn't actually commit to 1.5C, and it's blindingly obvious the rest of the world isn't going to do what is required to stay under 1.5C anyway, so it's not obvious what this was doing in the legislation in the first place.”

Frame notes that the actual temperature target in the Paris Agreement is a band, and the text says it "aims… to strengthen the global response to the threat of climate change… by holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels."

‘Significant’ uncertainty around methane emissions

However, Martin Manning, adjunct professor of the School of Geography Environment and Earth Studies at Victoria University, says he worked with the Global Strategic Communications Council, a group campaigning for a safe and stable climate, to put together the original letter. “I don't know why Dave Frame would think it was stimulated by the Climate Change Commission.”

He says that Frame’s concerns seem to be about how the FT article raises issues with the choice of a metric to compare methane with CO2. “But that is not quite the same as what was in the letter that went to Luxon on how to set an appropriate national commitment to the Paris Agreement to keep well below 2C warming.”

Manning says that over-simplified metrics like GWP or GWP* have defects that are covered in a large number of science papers. “Instead it is not hard to run a simple climate model approach like FAIR or MAGICC that can be done in a way that matches major climate models quite well.”

But Manning warns that there are also some structural changes going on with the atmospheric chemistry that removes methane. While methane removal rates have increased in the past 25 years, total methane emissions have actually increased by more than given in the last IPCC report.

“This is reflected in a growing consensus, over the last three years of peer reviewed papers on the methane budget, accepting that much of the record methane increase is coming from a response of wetlands to climate change. That matches paleoclimatic data which shows significant methane increases occur as the planet warms.”

Manning says that politicians need to recognise “significant uncertainties” in both future methane removal rate and the extent to which wetland emissions can increase. “As the letter to the Prime Minister said, if NZ accepts the Paris agreement then ‘Nationally Determined Contributions should reflect their highest possible ambition’.”

Impact on other sectors?

Christina Hood, head of Compass Climate, is concerned the government appears to be heading toward endorsing the weakest possible 24% methane target in the existing range.

“Methane has an extraordinarily high warming impact. An 11% change in the 2050 methane target (from mid-range 35% to low-end 24%) is equivalent warming to around 440Mt of carbon dioxide emissions/removals, according to the Parliamentary Commissioner for the Environment.”

She says New Zealand would need to plant around an extra 850,000ha of pine to compensate for that change.

“We are in a climate crisis and we should not be [amending] targets to do less than we have already committed to. If there's going to be a 11% weakening in the methane target, I look forward to seeing the plan for an extra 440Mt of CO2 emissions reductions or removals.”

NGOs send their own open letter

New Zealand NGOs Greenpeace Aotearoa, WWF-New Zealand, the Environmental Defence Society, Lawyers for Climate Action NZ, and Forest and Bird, also wrote their own open letter to prime minister Christopher Luxon last week, with a similar message about methane targets and requesting a meeting about the issue.

The letter says that weakening national methane reduction targets, would undermine commitments under the Paris Agreement and was likely to breach New Zealand’s free trade agreement with the EU and the UK.

“Applying no additional warming to livestock emissions generally would lead to inequitable conclusions, putting most developing countries at a disadvantage compared to developed countries. Equity is at the heart of Article 4 of the Paris Agreement. Weakening our methane target by applying what is effectively a creative accounting tool that advantages developing countries with high historic methane emissions would seriously undermine our reputation as a good global citizen.”

Jessica Palairet, executive director of Lawyers for Climate Action, also commissioned a report on the issue last year.

She says that adopting a "no additional warming" based target would effectively allow New Zealand to maintain its current share of warming from methane into the future, “rather than seeking the deep reductions in emissions that the IPCC has made clear are needed now.”

She also underlines that, because New Zealand’s domestic budgets and NDCs are based on all gases combined, a reduction in ambition for biogenic methane would potentially mean greater reductions for other gases.

“We have not seen any analysis on the impacts of this burden placed elsewhere within the economy – in fact, the terms of reference for the Government's independent expert panel on methane science actually prevented the panel from doing this analysis, despite its importance.”  

Palairet says that there is a real risk that weakening methane targets could affect New Zealand’s access to export markets. “A 2024 report by Aotearoa Circle/Chapman Tripp highlighted the growing importance of climate and sustainability for our exporters. In particular, over 80% of NZ's exports by value now go to countries with mandatory climate-related disclosures proposed or in force - many requiring exporting companies to set robust and credible emissions targets. Market expectations and consumer demands for sustainability are also rising, increasingly reflected through private standards and embedded in key trade deals - such as the EU/NZ FTA.”

Weakening the methane target would be short-sighted and a big risk, Palairet says. “Our export partners could see through any accounting change – viewing it as an attempt to evade and weaken our climate responsibilities, and giving us a licence to continue our high methane emissions per capita well into the future.”