Methane target: too soft, too hard or just right?

Government targets for cutting methane were attacked as being too soft and too tough – but they roughly match what was deemed feasible by a recent farm-gas working group ... as long as scientists can deliver methane-shrinking powders or food additives for free-ranging cows and sheep.

Methane - the swampy gas produced by cow and sheep rumens - finally has its own place in New Zealand climate law, or at least a proposed place. Predictably, that place is now being hotly contested. 

A government bill due to go before a select committee in June proposes reducing methane by 10 percent from 2017 levels by 2030 and 24-47 percent by 2050, depending how events unfold.

Those targets were simultaneously attacked as being too tough (by some farming groups) and too soft (by some environmental groups and businesses). Critics argued all gases must fall to net zero to keep the climate more liveable, while farm lobbyists say the 2050 targets jump the gun.

Amid the flurry of press releases, there was little discussion of New Zealand’s third major greenhouse gas: nitrous oxide, which comes mostly from livestock urine and fertiliser. Nitrous oxide would have to shrink to net zero by 2050, just as carbon dioxide from cars and coal will - and Beef + Lamb NZ’s Jeremy Baker told Newsroom his industry was ready and willing to do this, despite the challenges. Crucially, nitrous and carbon emissions can be offset by tree planting on farms and elsewhere, but methane can't as the proposal is for gross cuts, says Baker.

However the reduction targets for methane are much smaller. 

Farming groups such as Beef + Lamb NZ and DairyNZ swiftly condemned the 2050 methane target as being more than was required to flat-line livestock's contribution to warming.

However the proposal for cutting methane roughly matches the range deemed feasible last December in a report by the Biological Emissions Reference Group, whose members include Beef + Lamb NZ, DairyNZ, Fonterra, Federated Farmers and MPI. The BERG's modelling showed that combining all the options for cutting farm emissions could reduce farms’ gaseous output by between 10-21 percent by 2030, and 22-48 percent by 2050, compared to business-as-usual.

But DairyNZ and Beef + Lamb NZ told Newsroom those BERG estimates relied on new technology becoming available, namely a methane inhibitor for dosing cows and sheep to make them burp less methane when digesting their meals. New Zealand and overseas scientists have been working on such an inhibitor for years, and the BERG report said there was “high confidence” it would be ready to be used on farms by 2050. If that happens, the two farming groups agreed they would be happy to see a stricter target on methane – but they don't want it set down now.

The Government has said the provisional range of targets will be subject to review by the soon-to-be-created independent Climate Change Commission in 2024, to take account of changes in scientific knowledge and other developments.

DairyNZ told Newsroom it was “understandable” the Government might have taken the methane-shrinking technology into consideration in setting its provisional targets but “we are cautious to see a target range set expectations based on technological solutions that are not yet available ... We do support the target being reviewed if and when those technologies do become widely available.”

Both DairyNZ and Beef + Lamb promote the lower numbers put out by the Parliamentary Commissioner for the Environment, Simon Upton, last year. In August, Upton issued a report saying 10-22 percent cuts to methane would be needed by 2050 to flat-line New Zealand livestock’s contribution to climate change (which end of the range depended on what other countries did). With those cuts, methane from Kiwi livestock would continue to make the same contribution to global warming as it is making today, but wouldn’t increase its share of climate damage.

Upton told Newsroom last year he explicitly hadn’t made any policy recommendations in his report about whether those numbers were a good target – he just wanted to get some numbers out showing what it would take to stabilise warming. The adequacy of the numbers received pushback from some climate experts, who argued “not worsening” our contribution was too unambitious, and that it wouldn't be possible to reduce CO2 rapidly enough to stay within 1.5C or 2C of warming without as much help as possible from also cutting methane.

But Beef + Lamb and other farming groups have been very keen to adopt Upton's numbers, arguing they should not be required to reduce their current, ongoing contribution to warming because carbon emitters in transport and other sectors are not being asked to do that. Because carbon dioxide is so long-lived, the only way to take heat out of the atmosphere would be carbon capture and storage, whereas, for methane, simply reducing ongoing emissions would take some of today's farm-related heating away. But Baker - chief insight officer for Beef + Lamb - said being asked to do that wasn’t fair: the goal for all gases should be “no additional warming”.

Baker said his organisation wasn't trying to get out of taking action: “We are committed to this. Farmers will be affected by climate change. We are happy to get nitrous oxide to zero - we will have to offset it with trees and it will be difficult, [but there’s] good scientific reasons to go harder on nitrous oxide than on methane.” If methane inhibitors arrived on the scene, Beef + Lamb would be happy for the 2050 target to be revised up, he said. “At moment the only option is to reduce the herd.”

Announcing the targets, Climate Change Minister James Shaw alluded to the various methane figures that have been released in the past year. “There was a range of scientific advice but they’re operating off different assumptions, so the PCE report that came out last year described a scenario of what they call 'no further warming above current base rate' but that’s not the same thing as what it takes to live within a 1.5 degree temperature goal, so part of the confusion that’s arisen from various sources actually is that different scientists are working on different scenarios, some on 2 degrees scenario some on 1.5 degree scenario some on the current baseline," he said.

In October, an IPCC report said countries needed to cut methane by 35 percent by 2050, to stay within 1.5C warming. Unlike the New Zealand-based, methane-only exercise that Upton asked for, it modelled the cost-effectiveness and impact of cutting different gases for the whole globe, and looked at the interplay between them. Today's methane targets appear to be drawn partly from a range of calculations in that report. 

At the other end of the spectrum, submission-writers on the early Zero Carbon Bill proposal wanted considerably deeper cuts: 91 percent of long public submissions on the proposed Zero Carbon Bill favoured getting all gases, including methane, to net zero, although, a little confusingly, almost a third of those people went on to say they’d be okay with some ongoing methane emissions, provided there were “significant” cuts.

Other advisers, such as the former PM's science advisor Sir Peter Gluckman, have argued New Zealand’s high number of ruminant animals per capita and world status as the highest per-capita emitter of methane poses a reputation risk, meaning methane should be cut as much as possible. 

Unlike many lay submitters, and unlike the scientific case for CO2, climate scientists generally agree that methane need not fall to zero to keep the climate reasonably habitable, or even fall too close to zero. But there are various policy and scientific arguments for how much or little to shrink it.

Methane mostly disappears from the atmosphere within a decade or two, although it leaves some lingering effects. That makes its lifetime short compared to carbon dioxide, which is basically immortal. But while methane remains in the atmosphere, it’s very potent.

A constant flow of methane from human activities already keeps the planet consistently warmer (maybe in the order of 0.25C to 0.4C warmer) than it otherwise would be. But, unlike CO2, if the flow stops, so does most of the warming - so cutting methane emissions (along with obliterating CO2) could cause temperatures to fall, or at least rise less than they would have.

The effect would be similar to taking carbon out of the atmosphere, as scientists hope to one day do with carbon sequestration. That's what leads groups like Beef + Lamb to say it isn’t fair to ask farmers to help reduce their warming from methane unless getting to negative emissions through CO2 capture is also part of the picture. The opposing argument is, essentially, every molecule counts, and that farming has played a large part in the world's warming to date. 

Meanwhile, climate scientists internationally are puzzling over an unexplained spike in methane, which might be more farms in the tropics, or rice paddies, or gas leaks - or maybe a sign the world's self-cleaning process for methane is breaking down.

Good farming, such as breeding and farm management, might reduce methane by an estimated 5-10 percent, according to previous estimates by Gluckman's office. Normal productivity gains might shave off 22 percent by 2050 (based on the gains of the last 20 years), but only if farms don’t increase dairy and meat production. Deeper cuts will require land use change, new technology or both, most likely.

Several farmers speaking through DairyNZ said they supported the Government's splitting off of methane, but that even a 10 percent reduction would be challenging. The best ways to improve emissions as of today were to reduce supplementary feed and not increase production when efficiency increased, the DairyNZ 'climate ambassadors' said. One added that farmers were ready to take the step of not increasing production when they got more efficient, to ensure gains in emissions-per-kilo of food stayed locked in. 

Agriculture is New Zealand's largest emitting single industry, contributing 48.1 per cent of emissions as New Zealand currently reports internationally. Methane makes up about 35 percent, with the rest coming from nitrous oxide.

According to a recently published Greenhouse Gas Inventory report, New Zealand’s net emissions rose by 23 percent since 1990, with the biggest recent increases coming from transport. The Government has noted cutting carbon is its biggest and most urgent priority. 

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