Sir Peter reports on the mitigation of agricultural greenhouse gas emissions

Arguments for focusing on carbon dioxide and nitrous oxide and giving less emphasis to methane are counter-productive, Sir Peter Gluckman says in a letter to Prime Minister Jacinda Ardern which accompanies his final report as the Prime Minister’s chief science advisor. Therefore he does not favour avoiding a focus on methane, despite the challenges such a focus creates.

He also says it it unrealistic to imagine a GHG-neutral profile from agriculture without offsets in various forms.

Those views are reflected in Sir Peter’s final report, which has been published today.  It is entitled Mitigating agricultural greenhouse gas emissions: Strategies for meeting New Zealand’s goals

The report’s conclusions are driven by consideration of the highly variable nature of New Zealand geography, soil types, climate, and farming systems, Sir Peter says in his letter to Ms Ardern.

This heterogeneity creates challenges for generalisation and identifying the best ways to proceed. There are actions that farmers can now take that will have some impact on GHG emissions, and some near-term technologies that could have further effect if further developed for and adopted into NZ farming systems. But

” … there is no current or foreseeable methodology that will provide an accurate measure of GHG emissions on an individual farm, nor of what any particular mitigation measure might achieve at a farm level. This has major implications for how to proceed.

“Emissions at an individual farm level can only be estimated through proxy measures using scientific models such as OVERSEER, which is subject to some debate over its utility as a direct regulatory tool across a range of farm types, and has other issues that currently limit its usefulness. Taking these factors into account, one option that seems feasible is to use a ‘farm plan’ approach whereby a farmer, with expert advice and science-based input, identifies mitigation strategies he/she will be accountable for adhering to.

“Compliance or otherwise with an appropriate farm plan could extend to other dimensions of environmental management and to animal welfare and could be linked to any market or regulatory incentive scheme. Such an approach would require greater focus on the skillset of appropriately accredited farm advisors.”

The report highlights where scientific and policy focus should be concentrated, and outlines actions in terms of farmer and industry practices as well as research and investment to speed up the development of the most promising abatement technologies and better quantification of GHG emissions.

Sir Peter says:

“In some cases, issues of social acceptance and regulatory approvals will need to be addressed pre-emptively. It is likely that significant trade-offs will be required and there will be conflicting views: these should be acknowledged.”

Sir Peter recalls in the letter his first meeting with Ms Ardern to discuss her priorities for his Office after she became Prime Minister. She asked him to report back on what the agricultural sector could do over the near and intermediate term to reduce its greenhouse gas emissions, enabling  New Zealand to track more effectively towards meeting its commitments under the Paris Agreement on climate action, and ultimately, the government’s carbon-neutral goal.

The letter says:

“New Zealand is seen internationally as an efficient producer of high quality food and will remain a major agricultural producer into the foreseeable future. However, maintaining agriculture’s central role in our export economy will require the sector to be increasingly sympathetic to the environment. Part of that must include reducing its contributions to greenhouse gas (GHG) production, and this could be done over time probably without substantive impacts on productivity or economic returns. But doing so will likely require some complex trade-offs, consideration of new technologies, and significant changes in farming practice and land use.

“In order to fully understand the landscape, my Office convened two large expert group meetings of governmental, farming and food sector stakeholders and have met with many experts from relevant sectors in smaller groups to discuss the opportunities and challenges in this complex area.

“My Office canvassed expert opinion on specific mitigation options and we have reviewed the scientific literature, including draft copies of analyses commissioned by the Biological Emissions Reference Group (BERG), a joint government and sector working group (due for public release in September 2018). I understand that the Productivity Commission, the Parliamentary Commissioner for the Environment and Interim Climate Change Committee (with whom I have met) will be providing Government with further evidence and/or advice on these and related issues in the future.”

Sir Peter’s report aims to present a high-level perspective on what would be needed to achieve meaningful reductions in greenhouse gas emissions, and greater offsets, in the agricultural sector. It integrates the work of various research efforts in New Zealand and abroad, briefly reviews available on-farm mitigation options, highlights emerging opportunities, and identifies gaps in knowledge or other barriers that need to be overcome if agriculture is to be included in the New Zealand Emissions Trading Scheme (ETS), or any other policy mechanism.

The executive summary says agriculture – in contrast to the power and transport sectors – has fewer options to make large emissions reductions quickly and cost-effectively.

“Obligating farmers to reduce their emissions should not impose a disproportionate burden on them relative to their international competitors, nor relative to other sectors within New Zealand. There are no zero-emission strategies for biological GHGs, yet there are many reasons to act aggressively to reduce their emissions. This goes beyond arguments of short-lived versus long-lived gases; there are also strong market and reputational reasons for driving down agricultural emissions while making farms more efficient and sustainable.

“Methane and nitrous oxide are the main GHG emissions occurring on farms. Methane, derived mainly from enteric fermentation in ruminant livestock, is a short-lived gas, but one that has contributed most to the sector’s increasing emissions since 1990.

“Although methane does not accumulate in the atmosphere like CO2 does, it has potent effects on near-term warming, and this potency increases with increasing rates of methane emissions over time. While noting that methane emissions from agriculture cannot, and need not be, reduced to zero, reducing global methane emissions quickly will impact the peak warming temperature and the rate at which CO2 emissions need to be reduced.

“The metrics used to account for the different gases are important, particularly if biological GHGs are to be included in the ETS or similar mechanism at any level, as different metrics have implications for carbon, nitrous oxide and methane budgets.

“Strategies exist now that can help reduce biological GHGs, but currently, individual strategies are only expected to have modest effects on total emissions reduction, and there are trade-offs between possible options that will require careful consideration at an individual farm situation.”

The main strategies relate to:

• On-farm land-use decisions that reduce GHG emissions per unit of land area or increase carbon sinks – including forestry and other tree plantings, and horticulture blocks.

• Feeding practices, grazing and pasture management – including forage selection and the balance between stocking rates per hectare and individual performance per animal.

• Animal husbandry including breeding for high genetic merit in terms of breeding, productivity and emissions profiles.

• Animal housing and effluent management

• Precision-farming techniques – including irrigation and fertiliser management

“Apart from substantial land-use change, reducing livestock numbers and afforestation, the report says, the main opportunities to reduce emissions significantly will depend on technological innovations; for example the development of market-acceptable nitrification inhibitors, and to rumen methane inhibitors such as 3NOP for use in pastoral systems.

“Developing a methanogen-inhibiting vaccine holds theoretical promise for reducing methane emissions across all ruminant livestock systems but no proof-of-concept in animals yet exists.

“A mission-led approach to research will continue to be needed. Social science research is also required to understand how best to encourage early adopters and to enhance uptake of effective strategies across the sector. For the longer term, unravelling the regulatory and social licence issues around the use of new and evolving technologies will be critical for continuing scientific advancement as part of the national effort to reduce New Zealand’s largest sources of GHGs.

Despite the many scientific, economic and implementation challenges, failure to take actions within the agricultural sector will not only be costly to those farmers who find themselves unprepared for change, it will also ultimately be costly to New Zealand.”

NZIAHS forum reminder: The NZIAHS forum, to be held in Science House in Wellington on Friday, is titled Agriculture and the Emissions Trading Scheme (ETS): How do we enable farmers to respond?

Source: Office of the Prime Minister’s Chief Science Advisor

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