Climate change: evidence review in Agriculture, Forestry, Land Use, Waste

Executive summary

Greenhouse gas ( GHG) mitigation is a central policy objective in Scotland. The Climate Change (Scotland) Act 2009 sets an interim 42% reduction target for 2020 and an 80% target for 2050 across all sectors of society (1990 baseline). As a priority policy area, it has become vital to better understand the co-benefits and adverse impacts arising from mitigation actions on our environment, economy and society. Integrated assessment is key in prioritising environmental actions, reducing adverse impacts and enhancing positive co-effects. This report aims to summarise evidence on the wider impacts ( WI) of GHG mitigation options ( MO) in the Agriculture, land use, land use change and forestry sectors ( ALULUCF) and those related waste management. The key findings of the review, namely a summary of the wider impacts and an overview of the challenges in quantifying and monetising these impacts are presented in this section. The ALULUCF MOs and WIs assessed in this report are presented in Table 1.

Table 1 ALULUCF mitigation options and wider impacts considered in the study

Wider impacts of the GHG mitigation options in Agriculture and LULUCF:

• Most impacts of the selected mitigation options were neutral or positive, with only a small proportion of adverse impacts.
• There is robust evidence on co-benefits deriving from all MOs, with multiple positive impacts from on-farm renewable energy, precision farming, anaerobic digestion ( AD), agroforestry, optimal mineral Nitrogen use, livestock health, reduced livestock product consumption, afforestation and peatland restoration, indicating the potential for delivering robust and varied co-benefits in a wide range of policy areas. Furthermore, co-benefits were identified for all MOs, though in a number of cases the evidence was moderate or weak.
• There is also robust evidence of adverse impacts from AD in terms of mono nitrogen oxide ( NO _x) emissions. Similarly for the effect of peatland restoration on water quality due to leaching of nitrogen and phosphorous, particularly in the first years of restoration.
• The effect on a number of wider impacts were variable (having both positive and negative effects in the same impact category), implying the need for specific tailored implementation which can maximise the benefits while reducing the adverse impacts. These variable effects were mostly associated with reduced livestock product consumption, afforestation, low emission storage and application of manure and peatland restoration. Variable impacts can be due to the varied technologies an MO might encompass (e.g. low emission storage and application of manure covers very different technologies), or that the effects depend on how the option is implemented (e.g. location is critical for afforestation), or that certain groups in society might experience benefits while others losses (e.g. reduced livestock product consumption).
• Evidence on the impacts of some MOs were weak, reflecting knowledge gaps, particularly in the case of reduced livestock product consumption, livestock health and optimal soil pH, low emission storage and application of manure and more legumes.
• Many MOs can have positive effects on air quality, water quality, resource efficiency and human health. Integrated approaches in these policy areas can promote these co-benefits. Crop health and cultural impacts may be affected by the lowest number of the MOs as assessed in this report, nevertheless the magnitude or in some cases regional/local importance of these impacts calls for further investigation.
• Household income, consumer and producer surplus, employment and cultural impacts were the wider impact categories where evidence on the effects was the weakest across the MOs, calling for a research agenda which explores the synergies and trade-offs of agricultural GHG mitigation with these areas. Soil quality, human health and social impacts were the impact cateogries with the least robust evidence basis.

Quantitative aspects of impact assessment:

• There is robust modelling capacity for most of air and water quality impacts and flood management. UK specific models are available to capture both the changes in farm management and in land use related to the MOs. Existing monetary values used by UK Government can be applied the major air pollutants (ammonia ( NH ₃), NO _x, PM), however, these values only include some human health impacts. Existing monetary values for nitrogen pollution relate only to specific locations in Scotland, while no monetary values were found for phosphorous pollution of water. Monetary values for flood risk can be captured by existing spatially explicit property damage values.
• Soil quality modelling focuses on soil carbon, with other aspects (like hydrologic and biologic characteristics) less explored. There is a knowledge gap in estimating the quantitative impacts of MOs which affect farm management rather than land use (i.e. MO1- MO9) on soil quality. Furthermore, currently only the production effects and erosion impacts (sediment in water-bodies) of soil quality can be captured in monetary terms.
• Larger scale land use changes related to afforestation and reduced livestock product consumption can be predicted using models that represent the economic drivers and the biophysical constraints. There are no models to quantify the finer changes potentially induced by on-farm renewables and planting more legumes. Similarly, existing models are capable of estimating the biodiversity impacts of MOs resulting from land use change, but finer, farm management changes related to changes in farm management ( MO1- MO9) cannot currently be assessed. Monetary values suitable for national scale assessment of biodiversity are available (they are based on the impact of habitat improvement on charismatic and non-charismatic species).
• No models or tools were found to quantify the WIs on animal health and welfare and crop health. The value of production loss impacts of animal and crop health may be captured using market values. Existing monetary values for animal welfare could not be linked to the potential welfare outcomes of the MOs assessed in this report.
• Economic models can quantify the impacts on household income, consumer and producer surplus and employment, and energy efficiency, though currently these models are more suited to assess larger scale impacts than on farm management changes.
• Modelling the impacts of human diet on health are well-developed, and air and water quality related health impacts can also be modelled with existing tools. But a number of more specific potential health effects related to some mitigation options (e.g. zoonoses and antimicrobial resistance) cannot currently be modelled. Estimates for the monetary value of human health exist and are used in UK Government policy assessments.
• Social and cultural impacts are difficult to quantify and no tools were found apart from those to quantify the recreational benefits of green space. Evidence on the monetary values of the cultural impact is limited, being based on impact of improvements to habitats on 'sense of place'. Currently there is no evidence on the valuation of social impacts.

Waste:

• The literature reviewed indicates that as waste is moved up the hierarchy, from residual disposal and treatment to recycling, the number of people employed per tonne managed (the 'employment intensity') tends to increase.
• There are indications that the employment intensity for recycling varies by material type. The recycling of plastics and aluminium is considered in the literature to lead to some of the highest employment intensities.