Reducing Greenhouse Gas Emissions In Scotland: The Contribution Of The Land Use Sector

Published on 18 May 2010 in Climate, water and energy

Introduction

Agriculture and the land use sector have an important role to play in the search for efficient means to tackle climate change. Fertiliser application, animal raising and soils disturbances are sources of greenhouse gas. However, there is:

the potential to reduce these emissions. By optimising the timing of fertiliser application, it is possible to reduce emissions. Animals can be managed in ways that reduce the amount of methane they produce. Soils can be cultivated so that disturbances are minimised (no or low tillage);
the potential to increase sequestration (in soils and in above ground biomass).Trees sequester significant quantities of carbon as they grow; the conversion of arable land to grassland also contributes to carbon sequestration in soils.

This note examines how the land use and agricultural sector could contribute to climate change mitigation targets. It reminds first how the agriculture and land use sector contributes to GHG emissions in Scotland; then describes how this could be reduced and the economic implications of such a strategy; and finally discusses the implications of this strategy for policy makers and land managers.

Key Points

The agriculture, forestry and other land uses sector acts both as a source of GHG emissions as well as a carbon store, contributing about 20% of total GHG emissions, but removing about 16% through carbon sequestration (Scottish Executive, 2006).
Agricultural activities are an important source of the GHGs nitrous oxide (N2O) and methane (CH4), associated with both animal and crop production. Typically, they contribute about 12% to total GHG emissions in Scotland (Jackson et al., 2008)
The Land Use, Land Use Change, and Forestry sector is estimated to have been a net sink since 1999, amounting in 2006 to some 1.95 Mt CO 2 equivalent {Jackson et al., 2008}. Most of this is due to the uptake of CO2 by forestry – if this is excluded, then land use and land use change emits 13.7 Mt CO2e y^-1
The Scottish Government has an aspiration of increasing forest cover from 17.2% (current level) to 25% by 2050. The aims of this strategy is to both increase carbon sequestration and to provide resource for the growing woodfuel industry (Forestry Commission, 2006).

Research Undertaken

The Future carbon budget for UK agriculture, land use, land use change and forestry sectors were analyzed in a report to the Committee on Climate Change, involving SAC, Macaulay and consultants (see Moran et al., 2008). The budget is based on a marginal abatement cost curve (MACC) derived for a range of mitigation measures over a range of adoption scenarios.

The results indicate that in 2022, the date chosen as the period ending the 3 first carbon budgets, around 6.36 MtCO2e could be abated at negative or zero cost. Further, by the same time, over 17% of agricultural GHG emissions (7.85 MtCO2e) could be abated at a cost of less than the estimated 2022 Shadow Price of Carbon (£34/tCO2e). For forestry,the feasible potentials were estimated to range from 0.20 – 1.67 MtCO2e, i.e. this annual abatement could be achieved in the forestry sub-sector at a cost of <=£100/t by 2022. Actual cost-effectiveness is a saving of £7.12/tCO2e (£2006). This abatement is achieved by afforestation – increasing the planting rate to 30,000 ha/year from 2009; knowing that planting rates are currently less than 10,000 hectares, of which 40% is in Scotland.

Additional plantations do not only offer the potential to increase carbon sequestration. It also provides an additional resource for the energy sector, where the use of wood as a fuel displaces emissions from fossil fuels. In the construction sector, timber can substitute for carbon intensive materials such as concrete, steel or aluminium. Due to data uncertainty, these substitution potentials were not captured in the analysis but will help to decarbonise the UK and Scottish economies.

Policy Implications

The land use sector has an important role to play in a future low carbon economy. Direct emissions have the potential to be reduced; while sequestration can be increased. Also, forestry can contribute, indirectly, to reduce emissions from other sectors (energy and building materials). From a policy perspective, the right incentive mechanisms will have to be put in place. Forest planting rates are currently low because of distance from markets and low returns and/or the opportunity cost of land. Landowners need to receive clear signals from policy makers. Another challenge for policy makers will be to make sure that the role of forests to tackle climate change does not conflict with other countryside amenities. From this perspective, it is likely that a mixture of various types of forests will be required, instead of large scale commercial plantations, which are the most effective from a carbon sequestration perspective.

Renewable energy (wind, water) also needs the participation of landowners as land needs to be set aside for the purposes of energy generation. This is another way for the land use sector to contribute to the low carbon economy. Provided that the right incentives are put in place, landowners could allocate the lowest grade land to energy generation.

Author

Robin Matthews & Guillaume Pajot r.matthews@macaulay.ac.uk

Topics

Climate, water and energy