This is a subscriber-only article
The central role of grass-based livestock farming in Ireland and New Zealand means these are the only two developed nations in the 2015 Paris climate agreement where agriculture is the main source of reported greenhouse gas emissions – accounting for half in New Zealand and one-third in Ireland. Within agriculture, methane from ruminant livestock is the main greenhouse gas in both countries, with nitrous oxide from fertiliser and manures also playing an important role.
While targets agreed at EU level apply to Ireland for 2020 and 2030, New Zealand is setting its own rules until 2050. A wide debate has been taking place over the Government’s upcoming zero-carbon bill. Several key proposals are on the table, including how to set 2050 targets and intermediary carbon budgets every five years, and the establishment of an independent Climate Change Commission to advise and monitor on this. Separately, farmers may be included in a trading system for greenhouse gas emissions permits, similar to milk quotas.
Irishman John Roche, science adviser to New Zealand’s Ministry of Primary Industries (including agriculture), told the Irish Farmers Journal the Paris Agreement’s goal of keeping global warming below 2°C had opened a discussion on how different greenhouse gases are treated. “Up until this point, we were talking about emissions, not temperatures,” he said. “There is an ongoing debate as to whether we run a split gas system, with methane separate from carbon dioxide and nitrous oxide.”
New research indicates stable methane emissions are unlikely to cause additional warming as the gas decays, on average, in 12 years in the atmosphere – unlike carbon dioxide or nitrous oxide, which continue to trap heat for centuries. In August, the Parliamentary Commissioner for the Environment commissioned an in-depth study from the New Zealand Agricultural Greenhouse Gas research centre, which brings together government, universities and the industry.
Climate inertia
The centre’s Andy Reisinger combined the latest knowledge on methane’s cycle, historical data on New Zealand’s livestock production and computer models used to simulate the global climate. He confirmed that capping methane emissions at a given level would stop increasing the gas’s concentration in the atmosphere after around a decade. However, “inertia in the climate systems” means “it would take several hundred years of constant methane emissions before warming due to those emissions ceases to increase entirely”.
By Reisinger’s calculations, New Zealand would need to cut its current livestock methane emissions by 10% to 22% (depending on how other countries perform) to ensure they cause no additional warming from 2050.
The Parliamentary Commissioner for the Environment and Reisinger both highlighted that government would also need to take the economic and social consequences of emissions cuts into account before setting new rules. “Policy decisions are not only based on science. They are also about how people feel about it,” said Roche.
Public consultation
The Ministry for the Environment has just published the results of a public consultation on the zero-carbon bill. More than 15,000 people made submissions and 91% were in favour of setting a target of “net zero emissions across all gases by 2050”. When multiple submissions filed on behalf of campaign groups such as Greenpeace were filtered out, a 58% majority still supported this option, while 22% preferred to stabilise emissions of short-lived greenhouse gases such as methane. The public consultation took place before the latest research on methane’s effects on global warming was published, including Reisinger’s study. Secretary for the Environment Vicky Robertson said the consultation was “one part of a base of evidence that will be used to draft the bill”, with “economic modelling, the latest science and other relevant reports” also considered. This includes another detailed report from New Zealand’s economic advisory body, the Productivity Commission. One of its recommendations is that “the Government should establish separate emissions budgets for short-lived and long-lived gases”.
The report also noted that a vaccine researched in New Zealand could reduce methane emissions from dairy cattle by 30% from 2030, however this remains uncertain.
All remains to play for on New Zealand’s zero-carbon bill in the New Year, and Roche said there was “wide commitment to live up to the Paris Agreement” among the country’s politicians.
SHARING OPTIONS: