Scotland's draft Climate Change Plan: 2026-2040: strategic environmental assessment - environmental report

5. Secondary, cumulative and synergistic effects

5.1. Introduction

5.1.1 This section considers possible secondary, cumulative and synergistic effects between all of the outcomes, policies and proposals set out within the Scottish Government’s new CCP which have been assessed. Given that it is unknown in which order and at what time intervals all policies and proposals will be brought forward, this section summarises the maximum potential secondary, cumulative and synergistic effects.

5.2. Assessment of effects

Air

5.2.1 The policies and proposals within the outcomes of the Transport, Agriculture, Waste and Energy Supply sectors have the potential for positive cumulative effects for air quality. Transport initiatives aimed at reducing private car use, the switch to EVs and decarbonising aviation may result in a reduction in air pollution and emissions levels. This effect could be reinforced by a broader move towards green energy production, reducing energy consumption requirements within buildings and transitioning away from fossil fuels, towards the use of alternative and renewable fuel sources across all sectors. In agriculture, more efficient farming and nutrient management practices may also reduce airborne pollutants associated with fertiliser use. Proposals in the Waste sector may also lead to a reduction in airborne pollutants locally. Some localised negative effects may arise from infrastructure development, such as the installation of heat networks, biomass systems, and retrofitting of buildings. These activities could temporarily affect air quality during construction phases.

Biodiversity, flora and fauna

5.2.2 Policies and proposals across the Transport, Agriculture, Business and Industrial Process, LULUCF and Waste sectors have the potential to result in both positive and negative cumulative effects on biodiversity. Synergistic benefits are likely where climate mitigation and biodiversity objectives align, such as through peatland restoration, which supports species-rich habitats while sequestering carbon, or circular economy measures that reduce resource extraction and associated habitat loss. Secondary benefits may also arise from improved soil health, water quality, and ecosystem connectivity, reinforcing resilience to climate change and supporting wider environmental goals. Waste reduction initiatives, particularly those targeting single-use plastics and promoting reusable alternatives, may lessen contamination in terrestrial and marine ecosystems, reducing harm to species and habitats. Some proposals may carry risks of localised negative effects; infrastructure upgrades, retrofitting of buildings, and the deployment of technologies such as carbon capture and storage could disturb habitats or species, particularly where works occur in sensitive areas or involve nesting sites. The production of sustainable aviation fuel may also exert pressure on biodiversity depending on biomass sourcing and land-use implications.

Climatic Factors

5.2.3 Policies and proposals across all sectors are anticipated to deliver significant positive cumulative effects on climatic factors, primarily through reductions in greenhouse gas emissions and enhanced carbon sequestration. Collectively, measures to improve energy efficiency, decarbonise transport, promote nature-based solutions, and accelerate industrial and energy system transformation are expected to reinforce one another. For example, circular economy initiatives (Waste sector package) can reduce demand for energy-intensive material production, complementing emissions savings from energy efficiency and low-carbon manufacturing. Land-based measures such as peatland restoration and tree planting can sequester carbon but also provide adaptation benefits by regulating water flows and reducing flood risk, which in turn supports agricultural resilience. The integration of carbon capture and storage with renewable energy deployment may further strengthen decarbonisation pathways and help reduce reliance on fossil fuels. Secondary benefits are also likely, including improved air quality, reduced resource pressures, and enhanced ecosystem services, which contribute indirectly to climate mitigation and adaptation objectives.

Cultural Heritage

5.2.4 Policies and proposals within the Buildings (Residential and Public) and Business and Industrial Process sectors have the potential to result in cumulative negative effects on cultural heritage. Measures such as the installation of solar panels, heat pumps, and external insulation on historic buildings may lead to visual and structural alterations, particularly where interventions are poorly designed or highly visible. Similarly, the deployment of renewable energy infrastructure and upgrades to support carbon capture and storage (CCS) could affect the setting and character of heritage assets. These impacts are likely to be localised but may become more pronounced where multiple developments occur within sensitive historic environments. Some of these effects may be offset, at least partially, by Waste sector measures around improved circular practices in the construction and demolition sector, encouraging the retention, reuse and repair of historic environment assets and materials.

Landscape and geodiversity

5.2.5 Policies and proposals across the Business and Industrial Process, Buildings, and Transport sectors have the potential to result in cumulative negative effects on landscape and geodiversity. The increased deployment of renewable energy technologies alongside infrastructure upgrades for CCS may alter landscape character, particularly in rural or visually sensitive areas. Where multiple developments occur within the same area there is potential for cumulative visual and physical impacts on landscape quality. These negative effects could be partially offset from proposals in the Waste sector, which may result in reduced demand for unsightly disposal and extraction infrastructure.

Material Assets

5.2.6 Policies and proposals across the Agriculture, Waste, Transport, Energy Supply, and LULUCF sectors have the potential to deliver positive cumulative effects for material assets. Circular economy measures within the Waste sector such as improved recycling services and reuse initiatives can extend the lifespan of built infrastructure and reduce demand for virgin materials. These effects may be reinforced where energy recovery from waste is integrated with heat networks, improving resource efficiency and supporting low-carbon infrastructure. Although increased electricity demand from transport decarbonisation may place pressure on existing networks, this could be mitigated through coordinated upgrades and planning. Synergies may also emerge where circular economy practices in construction align with land use changes, helping to reduce material consumption and support the longevity of built assets. Potential land use conflicts that may arise from the outcomes in the LULUCF sector highlight the need for careful spatial planning to balance natural and built asset protection.

Population and human health

5.2.7 Policies and proposals across the Buildings (Residential and Public), Transport, Agriculture, LULUCF, and Energy Supply sectors are anticipated to deliver predominantly positive cumulative effects for population and human health. Measures to improve energy efficiency in buildings, including retrofitting and enhanced standards, are expected to reduce fuel poverty particularly in vulnerable households. In the Transport sector, shifts towards EVs, increased public transport use, and cleaner fuels are likely to reduce air pollution and noise, contributing to better respiratory health and overall wellbeing in urban areas. Similar benefits may arise from agricultural initiatives promoting alternative fuels and efficient machinery, which can further reduce emissions. Proposals within the LULUCF sector centred on peatland restoration may enhance water quality and security, supporting public and private drinking water supplies. Additionally, cleaner energy generation and reduced reliance on diesel power stations, particularly in island communities, are expected to reinforce these health benefits. Waste sector measures driving the shift to more sustainable resource use and a circular economy may also lead to potential positive impacts under this topic. Collectively, these measures have the potential to improve environmental quality and have long-term positive effects for human health.

Soil

5.2.8 Policies and proposals across the Buildings (Residential and Public), Transport, Agriculture, LULUCF, and Waste sectors have the potential to result in both positive and negative cumulative effects on soils. Negative effects may arise from the siting and installation of low-carbon technologies such as district heat networks, ground source heat pumps, and biomass systems, as well as from the construction of new waste facilities, which could lead to localised soil disturbance and compaction. Conversely, new agricultural measures promoting reduced tillage and organic practices are anticipated to deliver significant benefits for soil health, improving structure, fertility, and resilience. Complementary actions within the LULUCF sector such as peatland restoration, rewetting, and strengthened monitoring, are likely to reduce erosion risks. These positive effects could be reinforced where tree planting and habitat restoration align with sustainable land management practices.

Water

5.2.9 Policies and proposals within the outcomes of the Agriculture and LULUCF sectors have the potential for cumulative benefits for the water environment. Agricultural measures aimed at reducing nutrient and pesticide runoff, alongside erosion control and wetland protection, may contribute to a reduction in pollutant loads entering water bodies. When these are implemented in parallel with LULUCF actions centred on peatland restoration there is potential for enhanced hydrological regulation across catchments. For example, reduced chemical input from agricultural land may support the functional recovery of downstream peatland systems, improving their capacity to store and filter water. Furthermore, the intended concurrent restoration of wetlands and peatlands across both sectors may lead to more stable water tables and improved flow regimes, particularly in areas where land use boundaries overlap. These effects could be reinforced where tree planting on agricultural land complements wider land-use change efforts, contributing to improved infiltration and reduced surface runoff. Similar positive effects for water quality in areas affected by leachate have been noted for measures set out in the Waste sector.

5.2.10 Some negative effects associated with development have been noted across several environmental topics, however these are thought to be localised and short-term in nature and could be mitigated though existing planning mechanisms.