Identifying and costing climate mitigation options for sheep farmers (PhD)

Multiple opportunities exist for mitigating greenhouse gas emissions on livestock farms. However, prioritising mitigation measures in policy is problematic because of the fragmentary nature of the evidence-base on abatement potentials and the heterogeneous nature of the industry. Limited literature exists on the abatement potential of sheep farm-specific mitigation measures and livestock measures applied in a sheep farm setting.

This study augments the evidence-base on mitigation opportunities for sheep systems in England and Wales through: estimating the cradle to farm gate greenhouse gas emissions of 64 sheep farms and assessing the relationship between farm variables and carbon footprint at the multi-farm level; producing a short-list of practical and effective mitigation measures based on the opinions of experts and farmers derived through Best-Worst Scaling surveys; developing marginal abatement cost curves for a case-study lowland, upland and hill sheep farm, indicating the abatement potentials and cost-effectiveness of short-listed mitigation measures.

The results convey two primary messages for industry and policy decision-makers:

1. the importance of productivity and efficiency as influential drivers of emissions’ abatement in the sector, particularly the cost-effective measures improving ewe nutrition to increase lamb survival and lambing as yearlings; and
2. the need for policy instruments to acknowledge and account for heterogeneity within the industry. Instances of heterogeneity include variation in farmer perceptions of the practicality of sheep breeding measures according to farm size and type, and differences in the abatement potential of individual measures linked to current farm management.

It is suggested that productivity and efficiency targets could be communicated to farmers through the use of productivity benchmarks, and that the construction of further case-study farm marginal abatement cost curves could allow guidelines to be developed which define the management scenarios and conditions in which each measure is most effective. Case-study farm-level marginal abatement cost curves are advocated as a potential tool to inform farm-level mitigation strategy in addition to refining higher-level policy.

The Challenge

Climate change remains a serious challenge for society. In response to this challenge, Government in Westminster and Cardiff have set targets for overall greenhouse gas (GHG) emission reductions from agriculture in England and Wales, while Scotland has its own Climate Change Bill and associated set of actions. Additional pressure to reduce emissions from food production is coming from supermarkets and non-governmental organisations. The red meat sector is obliged to respond to this challenge and Eblex have recently produced ‘Change in the Air: The English Beef and Sheep Production Roadmap’. In addition, Hybu Cig Cymru will consider similar issues in Wales in their forthcoming ‘environmental roadmap’. While many farmers acknowledge these issues and are keen to respond to the challenge, currently they lack solid information on what they should do, and how much any action will cost them. Recent Defra research on Marginal Abatement Cost Curves (MACC) in agriculture (Moran et al. 2009)1 considered a range of potential measures that could be undertaken at farm level in order to reduce GHG emissions. The work estimated the cost of implementing these measures and balanced this against their reduction in GHG emissions.  Unfortunately, it wasn’t able to consider any measures relevant to sheep farming. 

The Project

The work proposed in this PhD will extend the MACC approach in order to consider sheep farming. It will assess farmer attitudes to the proposed interventions in terms of practicality and acceptability, and will model the impacts of implementing the interventions on a series of case study farms.

This modelling work will benefit from on-going work at Bangor which has developed farm level models of GHG emissions.  These models work on a yearly time step and consider the GHGs emitted by animals, on-farm processes such as manure handling, emissions from ecosystems (e.g. nitrous oxide) and inputs to the farm, e.g. fertiliser and fuels.  All GHGs are estimated in accordance with life cycle assessment protocols, and all emission equations are based on IPCC approved methods.  Early uses of the model are described in Edwards-Jones et al. (2009)2, but more recent developments enable weekly assessments of emissions by stock in accordance with their size and management. They also provide estimates of on-farm carbon sequestration in soil and habitats.  These models are currently being used to estimate GHG emissions from 23 farms in the Cambrian mountains (funded by CCW, ends March 2010) and a further 100 farms across Wales (funded by WAG, due to end in 2011).  Inputs to the models are obtained directly from farmers during farm visits, and individual farm reports are returned to the farmers at the end of these projects.

1Moran, D., MacLeod, M., Wall. E., Eory, V., Pajot, G., Matthews, R., McVittie, A., Barnes, A., Rees, B., Moxey, A., Williams, A., & Smith, P. (2008) UK Marginal Abatement Cost Curves for Agriculture and Land Use, Land-use Change and Forestry Sectors out to 2022, with Qualitative Analysis of Options to 2050, Final Report to the Committee on Climate Change, London

2Edwards-Jones G, Plassmann K & Harris I M (2009) Carbon footprinting of lamb and beef production systems: insights from an empirical analysis of farms in Wales Journal of Agricultural Science 147:1-13

Objectives

The objectives of this project are:

1. To identify practical activities that sheep farmers can undertake in order to reduce the greenhouse gas emissions from their farms
2. To calculate the cost of each intervention to the farm business
3. To estimate the reduction in greenhouse gas emissions that would derive from each intervention on a series of case study farms
4. To assess farmers’ perceptions of the practicality of implementing the interventions
5. To determine the contribution that these interventions could make to meeting Governmental and industry targets for greenhouse gas reductions.

Approach

Possible interventions for reducing GHG emissions will be identified from the literature and from relevant experts.  These are likely to include options ranging from decreasing stock numbers, enhancing growth rates of lamb through feed, genetics and reduced disease burdens, optimising fertiliser use, soil management, carbon sequestration and input substitution.  The interventions will be defined so as to be as specific as possible to the practical farm situation.  The list of possible interventions will then be ranked by experts in order assess their potential for GHG reduction.  The most promising interventions will then be assessed by farmers according to the practicality of implementing them on-farm.  Farmer opinion on likely costs of implementation will also be sought at this time.  This process will yield a list of interventions ranked according to potential reduction in GHG and practicality of implementation.  (NB we have just completed a similar exercise for interventions related to reducing on-farm prevalence of E. coli O157 and are familiar with the relevant techniques).

The most favourable interventions options (i.e. those that are practical and offer significant GHG reductions) will be developed further so that all associated changes to the farm system are understood, and their actual impact on GHG emissions at the farm level will be modelled using our existing model and database of >100 sheep farms.  This has the advantage that no further data collection is required from farmers, and by selecting different types of farm (e.g.  upland, lowland, intensive, organic) it will be possible to understand variations in the levels of GHG emissions in different situations.

We will then use standard data sources, such as Farm Management Handbooks, Farm Business Surveys, surveys from Banks and farmer expertise to estimate the financial costs to farmers of implementing each intervention.  This will enable us to plot the cost of implementation and the associated reduction in GHGs on a range of farms.  Finally we will assess the impact of the interventions on GHG emissions from across the sector in England & Wales and consider its contribution to relevant policy goals.

NB: The empirical aspects of this work will focus on England and Wales for reasons of practicality, but the results will be of relevance to Scotland and Northern Ireland.  All data currently held in Bangor is on Welsh farms, so some data for English farms will need to be collected to supplement these data.  Also, while the focus of this work will be on sheep systems, inevitably many farms will also keep some beef and any effects of interventions on the beef herd will also be considered.

The Student

Anna Kaye Jones