Agriculture and greenhouse gas emissions: latest trends

With the COP27 climate conference wrapping up in Egypt, there is a global focus on how we can keep the 1.5-degree C warming target within reach. To do so requires all sectors to reduce emissions and transition to a net zero economy.

Each autumn, Defra publishes an agri-climate report looking at annual greenhouse gas emissions for agriculture. The 2022 report, covering emissions from 1990 to the end of 2020, was published at the end of October.

All the data is updated annually to take into account methodological improvements in the UK emissions inventory and is reported in line with UNFCCC requirements. The CLA would like to see the national inventory for agriculture include more granular detail so that the impact of farm management changes which may have a positive cumulative effect is better reflected.

The full report can be viewed on the government website, but some key findings from the latest publication are summarised here.

Despite an overall decrease since 1990, agricultural emissions have plateaued recently.

Between 1990 and 2020, total agricultural greenhouse gas emissions decreased by 16% from 54.6 million tonnes of carbon dioxide equivalent (MtCO2e) to 44.8 MtCO2e. However, over the last decade, agriculture has been responsible for a similar proportion – 11% – of the UK’s total emissions.

Under Defra’s current agricultural decarbonisation policy pathway, it is expected that agriculture will reduce emissions by 4.9 MtCO2e on average per year in England by the end of the Sixth Carbon Budget (which covers 2033 to 2037). This is largely through the existing and proposed Environment Land Management schemes and agricultural productivity grant schemes.

Looking beyond absolute emissions, there are some positive trends for agricultural emissions intensity.

Across cattle, dairy and pigs, emissions intensity decreased between 1990 and 2020. The analysis shows that emissions from producing a litre of milk have decreased by 22% since the 1990s, with 11% more milk produced from 21% fewer cows. Another success for the sector is that the greenhouse gas emissions from producing a kilogram of pork have fallen by 44%. Although nitrous oxide emissions from arable have remained largely unchanged, wheat yields have increased, suggesting that the UK is producing more wheat for the same amount of nitrogen.

Agriculture is estimated to have produced 48% of the UK’s total methane emissions for 2020. Of course, it is worth remembering that the main source of this - enteric fermentation from livestock - is part of a natural 12-year cycle, unlike burning fossil fuel (natural gas), which releases methane into the atmosphere that had been locked away for millions of years.

Nonetheless, there is a lot of focus on agricultural methane emissions as they have remained static since 2009, and methane is a more potent greenhouse gas than carbon dioxide. The majority of agricultural methane emissions come from enteric fermentation from cattle. This autumn, Defra released a call for evidence on methane-suppressing feed additives, which are a potential solution to this challenge, albeit one that requires significant research and development.

Methane is also produced from manure when it decomposes under anaerobic conditions. It is hoped that the government’s new Slurry Investment Scheme will help to reduce these emissions by providing grants for improved manure management.

Nitrous oxide emissions from agriculture in 2020 decreased by 5.1% compared to 2019, but the sector is still responsible for 69% of total nitrous oxide emissions in the UK. The major source of nitrous oxide is soil from nitrogen fertiliser and manures. As these latest emission figures are from 2020, it will be interesting to see how high fertiliser prices over the last year will have impacted nitrous oxide emissions.

Nutrient management is increasingly important on farms. Not only does it make good business sense to reduce input costs, but water and air quality are rising up the agenda, with nutrient neutrality affecting large areas of the UK. Many CLA members are already taking action to mitigate these environmental impacts.

As the lynchpin of greenhouse gas accounting, carbon dioxide is a very small part of agriculture’s emissions profile. Only 1.7% of carbon dioxide emissions (5.5 MtCO2e) in the UK were attributed to agriculture in 2020. This is the same proportion as estimated for 2019.

Most agricultural carbon dioxide emissions come from fuel use for plant and machinery, along with some from liming and urea application. Key to the reduction of this will be a switch to lower carbon fuel sources. But more research and development are needed if we are to switch from diesel-powered machinery to electric or perhaps even hydrogen power for farm equipment.

Reducing emissions from agriculture and increasing carbon sequestration from land use is key to the pathway to net zero emissions by 2050.

There are growing opportunities to do both as part of the move from the basic payments scheme to the government’s ‘public money for public goods’ model and various emerging environmental markets, which can provide access to private finance. For more information on the options available speak to your regional CLA team.