Research into the current and potential climate change mitigation impacts of environmental stewardship (BD2302)

Abstract

In March 2005 the UK Government launched ‘Securing the Future – UK Government sustainable development strategy’, a component of which is ‘sustainable production and consumption’. In addition, the Department for Environment, Food and Rural Affairs (Defra) launched its five year strategy ‘Delivering the Essentials of Life’ that addressed its vision of sustainable rural communities within the UK being economically and environmentally viable, and socially inclusive. The ‘Rural Development Programme for England 2007-2013’ that was under consultation between April and July 2007 aims to help farmers manage land in a more sustainable way including a reduction in the impact on climate change. It will increase the funding available for Environmental Stewardship (ES). This project, with its focus on the potential for greenhouse gas (GHG) mitigation by ES within England, supports the UK Sustainable Development Strategy and a Defra Strategic Priority 'Climate change and energy', with reduced GHG emissions one strategic outcome. Environmental Stewardship was launched to build on the already successful Environmentally Sensitive Areas (ESA) scheme and the Countryside Stewardship Scheme (CSS). For land within an ES agreement the landowner receives a payment to compensate for any income foregone incurred (for example a reduction in or loss of crop yield or an increase in management costs) to a maximum 100%. The current objectives of ES include the protection of soil and water, the enhancement of biodiversity and resource protection. The alterations in land use and land management that an ES agreement requires may also have implications for climate change mitigation. An increase in the global mean temperature as a result of increased retention of thermal radiation by the Earth’s atmosphere, has raised concern over global warming and uncertainty over future impacts on the climate. Climate change has been addressed globally by the Framework Convention on Climate Change (FCCC) at the Earth Summit of 1992, then by the Kyoto Treaty of 1997. The Kyoto Treaty commits industrialised nations to a reduction in GHG emissions, in particular carbon dioxide (CO2), by 5.2% below their 1990 levels during the first commitment period, the Quantified Emission Limitation or Reduction Commitments (QELRC), between 2008 and 2012. The EU is required to collectively reduce GHG emissions by 8% while the UK target is a 12.5% reduction. The UK GHG emissions in 2005 were 15.3% below 1990 levels although much of the decrease between 2004 and 2005 was due to a 4.6% reduction in emissions from the domestic sector. The UK has a target to reduce its emissions by 20% by 2010 and 60% by 2050. Carbon dioxide is one of six main GHGs known to act as a barrier to thermal radiation6. Others include nitrous oxide (N2O), methane (CH4) Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6). Each of the GHGs listed has a different potential to cause global warming but may be standardised on a single scale as eq t CO2e, its global warming potential (GWP). Within agricultural systems, the main sources of GHG emissions are from: 1. CO2 released from burning fossil fuel (7.102 MT CO2e from UK agriculture in 20055 (13.5% of UK agricultural emissions) either during (a) product manufacture (of pesticides and fertilisers), their packaging and transport (to farm); (b) application by spraying or spreading or fuel consumed by tillage operations and drilling; (c) indirect energy (fuel consumed during machinery manufacture and calculated based on depreciation per operation). Carbon dioxide is also released from high C containing organic (peat) soils (for example lowland raised bog and fen habitats) during decomposition under aerobic conditions following land drainage5. 2. N2O released from soils and from livestock manures and during the manufacture of nitrate fertiliser (26.961 MT CO2e from UK agriculture in 2005 (51.2% of UK agricultural emissions). 3. CH4 released from ruminant animals and from livestock manures (18.561 MT CO2e from UK agriculture in 20055 (35.3% of UK agricultural emissions). Environmental stewardship options may include a reduction in or the elimination of for example fertilisers, pesticides and cultivations which will potentially impact upon climate change through a reduction in the GHG emissions(EDP) associated with their manufacture and application. These options may also require that the land is removed from agricultural production and this risks the displacement of that production elsewhere, either on the same farm or outside of the UK. The importance of energy conservation and mitigating climate change in the UK was highlighted in the Energy white paper: our energy future - creating a low carbon economy and more recently the Energy white paper: meeting the energy challenge published in 2007. Further pressure to maximise overall energy efficiency coupled with reduced dependence upon fossil fuels has arisen in light of estimations that a peak in oil supply is imminent. In addition to the reduction in GHG emissions through alternative management strategies, it may be possible to increase the carbon (C) stored within the soil, the soil organic content (SOC) or above ground, the above ground C (AGC). The SOC and AGC may be increased by a change in land management such as conversion of cultivated land to woodland or grassland, the incorporation of organic manures or through reduced tillage. A major barrier to successful agricultural GHG mitigation has been cited as ‘transaction costs’ whereby farmers will not adopt otherwise unprofitable agricultural GHG mitigation practices in the absence of policies or incentives. The payments made under ES may already overcome this barrier should positive GHG mitigation under ES be identified. This project has provided an estimate of the GHG emissions(EDP), both on and off farm, associated with land under the various ES options (and C mitigation through changes in C sequestration) to provide an overall estimate of the net positive or negative change in CO2e emissions. A robust, testable and cost-effective methodology to calculate the net CO2e emissions of a given management practice on agricultural land requires development. This research has the potential to make an important contribution to developing such a methodology. It first defines a baseline set of conditions in order to provide a reference point against which any changes in land use through management under ES may be compared and the net increase or decrease in C equivalent emissions quantified. Since the aim of the project is to identify changes in CO2e emissions, the quantification of stored C that does not change is not within scope. Reference has been made to the C storage potential of each habitat within ES and the importance of its continued maintenance or restoration even though the net change in emissions may be small. The overall impact on a national scale based upon the total area (ha) of uptake of each option within England as supplied by Natural England has then been quantified. The project does not aim to quantify the differences in the changes in C flow at a regional level based upon soil type, annual rainfall and through exact vegetation classification. Mean values have been used in many cases but they do allow comparisons between management scenarios and identify the main mechanisms of change associated with the management of each ES option.