Refined greenhouse gas reporting refocuses policy on emissions from agriculture


Description of impact

SRUC’s internationally impactful research work underpinning greenhousegas emission calculations has improved the accuracy of estimates fromUK agricultural systems and showed soil-derived emissions ofnitrous oxide are lower than previously estimated.

The UK Climate Change Act sets legally binding restrictions on total greenhouse gas (GHG) emissions and progress towards these targets is assessed against the annual UK-GHG inventory. The United Nations’ Intergovernmental Panel on Climate Change (IPCC) guidelines allow the UK-GHG inventory to be updated with improved data, analysis and estimates of Emission Factors (EFs).
High accuracy reporting is important to enable effective mitigation measures and policies. However considerable uncertainty has surrounded the portion of agricultural GHGs attributed to nitrous oxide (N2O) in the UK-GHG inventory. This is particularly significant because of the high global warming potential of N2O (298 times that of carbon dioxide).
SRUC researchers developed an integrated, and interdisciplinary research programme, looking at UK-specific climatic, geographical, and farming practices, to improve the accuracy of GHG-UK reporting and help deliver policy for future “low-carbon” farming systems.
Most notably, this work has shown that soil-derived emissions of N2O are lower than previously calculated (prior to 2016) but estimates for methane (CH4) emissions remain unchanged. CH4 has been shown to account for a greater proportion of overall agricultural GHG emissions in the UK than previously thought.

A UK-specific method for increasing the precision of emissions factors

SRUC played a leading role - managing seven of 37 national experiments (resulting in 12 peer reviewed publications) - in the multi-disciplinary, collaborative GHG Platform Research Programme, which involved 15 UK research groups.
By leading the national programme of field experimentation, we provided evidence for a UK-specific method of calculating emissions of N2O. This model takes account of soil type, fertiliser, and rainfall, and has now been incorporated into the most recent inventory reporting on N2O emissions from 2016 onwards; first reported in 2018.
Research on nitrous oxide emissions has been developed in a series of papers published between 2016 and 2019 and demonstrates that newly calculated emissions fall well below previously published estimates. For example, the Emission Factor for urine of grazing livestock was reduced from the previous inaccurate estimate of 2% to our improved estimate of 0.44%. Nitrous oxide emissions from soils are now 40% lower across the time series from 1990 than were reported prior to our research.

Pathways to impact

As a result of our work, methane contribution to agricultural emissions is recognised as higher than previously calculated (54% versus previously estimated 48%), so policies have been developed to increase focus on mitigating emissions from livestock production rather than from soil.
The improved EF accuracy has directly impacted the farming industry through advisory support and policies developed in the Scottish Government’s Climate Change Plan (2018).
Impact on UK GHG reporting and carbon budgets
Our GHG research has also provided information on the potential mitigation in UK agriculture and the cost-effectiveness of mitigation methods to the Committee on Climate Change (CCC). The CCC used our results in their carbon budget recommendations, which in turn form the basis of UK Carbon Budgets including those published at the end of 2020 and set the target date earlier for the net zero target in the Climate Change (Scotland) Act 2009 (amended 2019).
Research results also informed Scotland’s Climate Change Plan, which sets out the planned policies to achieve the climate targets, and influenced policies on nutrient management, soil testing, livestock management and precision farming.
Impact on economy through footprint calculator
Our research has driven the development and improved design of an on-farm GHG calculator tool (Agrecalc) that calculates resource use and GHG emissions for the whole farm, per enterprise and per unit of saleable product. The calculator, which has been used to footprint more than 4,000 farms, reduces costs by an average of £10,000 per year while achieving approximately 10% reductions in farm carbon footprint.
Agrecalc, developed in conjunction with SAC Consultancy, has also influenced Scottish Government climate change policy by supporting the Beef Efficiency Scheme (BES, 2018), which aims to support beef breeders to improve their efficiency,
sustainability, and quality of their livestock.

This is an edited version of an impact case study, which formed part of a joint submission with the University of Edinburgh to REF2021.