The methodology used to report methane emissions has always been an important topic for both the NFU’s Livestock and Dairy Boards.
Farming is in a unique position to provide some of the solutions to reduce emissions, lower global temperature as well as producing nutritious products to feed our growing population.
Currently, all greenhouse gases are reported jointly under various domestic and international obligations. GWP100 is used to convert different greenhouse gases into CO2 equivalents but has been acknowledged to not be as accurate when measuring the temperature response of short-lived emissions such as methane, and does not account for its removal from the atmosphere.
At a recent meeting of the boards, the NFU has updated its GHG (greenhouse gas) emissions policy position with a move towards supporting a split-gas approach.
This new method aims to help producers understand and reduce emissions on farm, as well as ensure that GHG emissions are calculated as accurately as possible.
Split-gas accounting
We need to make sure that GHG (greenhouse gas) emissions are calculated in as accurate a way as possible to help producers to understand and reduce emissions as much as possible.
Government, devolved authorities, government agencies, and the wider food supply chain should report on GHG emissions in a split-gas approach when reporting long-lived and short-lived GHGs from agriculture.
The UNFCCC (United Nations Framework Convention on Climate Change) most often uses a single basket approach to convert all GHGs to a carbon dioxide equivalent (CO2e) using GWP100.
Expressing methane emissions as CO2e emissions using GWP100 (as Nationally Determined Contributions currently do) overstates the effect of constant methane emissions on global surface temperature by a factor of 3–4. It also understates the effect of any new methane emission source by a factor of 4–5 over the 20 years following the introduction of the new source.
This means the real-time impact of planned emissions reductions cannot be properly understood and policies based on GWP100 may therefore be less effective in terms of constraining warming, particularly in the near term.
A split-gas approach distinguishes between long-lived and short-lived GHGs allowing a more accurate quantification of the different warming impacts of each gas.
The NFU believes the extra transparency of a split-gas approach will, over time, produce shifts in policy which better protect our future climate and more accurately reflect the contribution of the agricultural sector.
“A split-gas approach that distinguishes between short-lived gases like methane and long-lived gases like carbon dioxide would allow for more accurate measurements, better informing policy decisions and more clearly recognising the progress UK agriculture is making.”
NFU Deputy President Tom Bradshaw
Warming based metrics
Government and industry should also form a unified approach to dual accounting by reporting on GHG emissions from agriculture at the national scale using GWP100 and a ‘warming based metric’.
This is an evolution of the NFU’s previous policy position from 2022 which asked for dual accounting of GWP100 and GWP*. Using the term ‘warming based metric’ allows the NFU to respond to evolving scientific metrics for methane.
The current practice of using GWP100 alone can create ambiguity by obscuring the warming impacts of the different gases.
Although GWP100 works well when summing or comparing the warming impact of various long-lived GHGs, such as nitrous oxide and carbon dioxide, it does not accurately represent the warming impact of short-lived GHGs, such as methane, the main emission from farming.
If only GWP100 is used for the quantification of agricultural emissions, we recommend a cautionary note caution should be applied.
The NFU therefore advocates the use of dual reporting with GWP100 and warming-based metrics, which have already been recognised by the IPCC (Intergovernmental Panel for Climate Change) as providing better estimates of warming impact.
Calculating GHG emissions accurately
NFU President Tom Bradshaw said: “British farmers and growers are committed to tackling climate change, all while continuing to produce high-quality, sustainable food for a growing population.
“However, the current system of measuring greenhouse gases overstates the impact of ongoing methane emissions while simultaneously understating the impact of new sources, meaning that the true picture of farming’s climate impact is misrepresented.
“A split-gas approach that distinguishes between short-lived gases like methane and long-lived gases like carbon dioxide would allow for more accurate measurements, better informing policy decisions and more clearly recognising the progress UK agriculture is making.
“Government investment to allow farmers to access the tools and technology that are needed to further reduce emissions is essential. The NFU will continue working with Defra to ensure that future policy reflects both the latest science and the realities on farm.”
NFU asks
The NFU is now asking for:
- The government should follow best scientific practice, using a split-gas approach when reporting long-lived and short-lived GHGs from agriculture.
- A unified approach to dual accounting with government and industry reporting on emissions from agriculture at the national scale using GWP100 and a warming based metric.
- When GWP100 is used for the quantification of agricultural emissions, we recommend the following caution should be applied: “CAUTION: this data combines multiple gases as CO2-equivalent using GWP100. This overstates the effect of constant methane emissions on global temperature by a factor of 3-4, while understating the effect of any new methane emission source by a factor of 4-5 over the 20 years following the introduction of that new source.”
- A joined-up approach to GHGs across government departments – for example, when looking at air quality under the Clean Air Strategy and GHG emissions reductions versus the future of ELMs.
- Any target setting for methane should be co-designed with producers to ensure it is achievable and practical.
- Any emissions targets must be outcome based, fair and not overly prescriptive; producers must be able to choose how best to reduce emissions based on their production system.
- Support and incentives, both from the government, the wider supply chain and the end market are essential to help enable British farmers to meet climate targets.
- The government should recognise and help further develop the different opportunities available to beef and dairy herds to reduce and offset their emissions.
- The National GHG Inventory must accurately capture different emission reduction practices in all farming systems and be dynamic enough to adjust when new and more accurate data is reported.
- Consistent and simple messaging to consumers on the temperature impacts from methane and the biogenic carbon cycle, including finding a more suitable way for the carbon footprint of a food product to be measured.
- Incorporate the latest warming-based metrics into on-farm GHG calculators, while ensuring that individual producers are not disadvantaged for expanding when national
- Herd/flock emissions remain unchanged or are decreasing due to uptake of new tools and technology.
- The impact of genetics and selective breeding on reducing methane emissions to be measured with similar warming-based metrics.
