Comment: A one size fits all Zero Carbon Bill won't reflect New Zealand's unique landscape, economy and society, writes Federated Farmers policy advisor trade and climate change, Macaulay Jones.

Additional research shows a target of a 10 per cent reduction in biogenic methane is in the ballpark of what is needed in order to achieve carbon neutrality in the New Zealand agricultural sector by 2050.

Unlike carbon dioxide, methane is a short-lived greenhouse gas and does not need to fully stop being emitted in order to achieve zero carbon equivalent (or no additional warming).

Methane quickly cycles in and out of the atmosphere and only a small reduction is needed to fully compensate for the brief time methane is warming the atmosphere.


Federated Farmers applied the work carried out by an international team of researchers, which demonstrates that a mere 0.3 per cent annual reduction in methane is needed for the gas to be zero carbon equivalent.

It was on this science-based 2050 zero carbon target that Federated Farmers arrived at a commitment to reduce agricultural biogenic methane levels by 10 per cent by 2050 in New Zealand – (2020-2050)*0.3%≈10 per cent.

However, since this commitment was made there have been two substantial pieces of research published that show while a 10 per cent 2050 methane target is in the ballpark it may not be precisely accurate and further research tailored to New Zealand is desperately required to better inform the Zero Carbon Bill (ZCB).

On July 22 the NZ Meat Industry Association (MIA) and the Dairy Companies Association of NZ (DCANZ), released research undertaken by Nicholas Leach of the Department of Physics, Atmospheric Oceanic and Planetary Physics at the University of Oxford. This research examines the Government's ZCB methane targets.

In his analysis, Nicholas Leach used methodology consistent with the Intergovernmental Panel on Climate Change's (IPCC) recent Special report on 1.5°C, which was used by the Government when setting the emission reduction targets in the ZCB.

According to the research, by following the Government's conditions – a target consistent with the IPCC global pathways for limiting climate change to 1.5°C and net zero for all greenhouse gases except short-lived biogenic methane – the actual global biogenic methane reduction required by 2050 is 7 per cent.

Read more from Federated Farmers here.

This 7 per cent figure produced by Nicolas Leach, and the 10 per cent figure by Allen et al, has also been reinforced by the IPCC's special report on climate change and land, released on August 8.


The report dispels false claims of the practicality of a universal vegetarian diet and highlights the ability of emissions efficient livestock farming to both feed a growing global population and to fight climate change.

The farm systems used, lack of government market assistance and favourable natural capital incredibly make such 'low-emissions farming practices' standard operating procedure for livestock farmers in New Zealand.

Below is an excellent quote from the report that has been left out of much of the media coverage.

"Balanced diets, featuring plant-based foods, such as those based on coarse grains, legumes, fruits and vegetables, nuts and seeds, and animal-sourced food produced in resilient, sustainable and low-GHG emission systems, present major opportunities for adaptation and mitigation while generating significant co-benefits in terms of human health."

The report also tackles the same question grappled with by Allen et al, Nicolas Leach and the Zero Carbon bill in New Zealand; that is what level does biogenic methane need to change by in order to no longer contribute to additional global warming by 2050?

The special report details various modelled shared socio-economic pathways (SSPs), which are consistent to limiting peak atmospheric warming to various targets.

Katie Milne: Enjoy NZ meat and dairy without guilt

Methane emissions from 'Agriculture, Forestry and other Land Use' (AFOLU) relative to 2010 is one variable that is altered in the modelled SSPs.

The report states that global AFOLU methane emissions of the gas need to decrease by a mean of 11.4 per cent in order to limit atmospheric warming to 1.9 watts per square meter (a proxy for 1.5 degrees) in SSP2 (a middle of the road pathway).

It is important to note that, just as is the case for the IPCC 1.5 Degree report, the research conducted by Nicholas Leach and the IPCC in the 2019 IPCC Land report makes global recommendations which should not be copy and pasted into the domestic legislation of an individual country.

Just as many have criticised the government for doing so in the current text of the ZCB, it would be equally unwise to make the same mistake, but with another international report.

Rather, as is clearly stated as a first preference in Federated Farmers' submission on the ZCB, why not have the newly formed Climate Change Commission set the target?

The Commission should be a collection of the most impartial experts on the matter and should be best placed to reach an objective scientific outcome on how methane levels in New Zealand need to alter in order to be equivalent to zero carbon – the goal for all other gases in the country.

International reports are useful for providing a framework for domestic policy but New Zealand is a unique nation, with a unique landscape, economy and society.

While it is encouraging to see that 7 per cent, 10 per cent and 11.7 per cent may be in the same ballpark, it is also alarming to see that the current 2050 ZCB methane targets, of 24-47 per cent, are not even in the correct postcode.