Objective | Purpose | Scientific context |

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Objective. The main objective of this DEFRA-funded project is to develop a system based on high-resolution spatial soils and land use data coupled to a dynamic simulation model to predict carbon fluxes from soils resulting from land-use change. This system will be applied to calculate annual CO2 losses from soils at the national and regional levels for use in the IPCC / UNFCCC National Greenhouse Gas Inventory. Results will be provided for 1960 to 2050 and will examine the likely interaction between land-use change and climate change. Uncertainty in these estimates will be assessed. In the final stage of the project, possible agricultural mitigation options will be examined and their potential to reduce net CO2 emissions quantified. Results will inform the UK government in its post-Kyoto UNFCCC negotiations.

Purpose As part of its climate change programme, the Department for the Environment, Food and Rural Affairs (DEFRA) is funding a project led by the Centre for Ecology and Hydrology (CEH) to quantify soil carbon fluxes associated with land management and land use change. This feeds into the UK Greenhouse Gas Emissions Inventory (GHGEI) category on Forests and Land Use Change. Maintaining and regularly updating the inventory is a commitment under the United Nations Framework Convention on Climate Change (UNFCCC) and the EU Monitoring Mechanism for greenhouse gas emissions. The ITE researchers are using a step change in a soil-related coefficient to estimate the impact of land-use change on soil sinks and sources of carbon. This generates figures required for DEFRA’s annual reports to the UNFCCC and the EU Monitoring Mechanism.

Article 3 of the Kyoto Protocol lays the foundations for inclusion of human-induced changes in fluxes of C from agricultural soils and land-use change and forestry in Annex I Parties’ commitments. However there is a great deal of scientific uncertainty associated with C flux estimates, particularly on a regional basis. This project will help reduce the uncertainty in the UK estimates and projections of C flux from soils. The outputs will also help inform the UK’s position in international negotiations on methodological issues for reporting C fluxes from soils.

This longer-term approach will involve adapting existing models of soil processes to calculate the loss or accumulation of carbon by different soil types over time. It will also provide a more accurate assessment of organic matter balances in agriculture, and ensure that soil work for the UK GHGEI is integrated with the large programme of research funded by DEFRA on soil organic matter and sustainability.

Scientific context The current method for providing estimates of soil C fluxes from soils as a result of land-use change for the UK Greenhouse Gas Emissions Inventory (GHGEI) involves the use of a step change in a soil-related coefficient . We have recently developed approaches that can be used to estimate soil C fluxes which rely upon dynamic simulation models linked to spatially explicit datasets . This provides more process-based and spatially explicit estimates of soil C flux which explicitly account for difference in climate, land-use, and soil type. This approach allows climate change and land-use change to be examined either separately or together and for interactions to be predicted. Other recent work has focused upon agricultural carbon mitigation options . Using the simulation model approach described here, it will be possible to also examine possible carbon mitigation options in UK agriculture in a spatially explicit way, taking account of soil and climatic differences across the UK. All model outputs can be provided at both national and regional level.