Research and analysis

Evidence on potential environmental impacts and social implications of selected greenhouse gas removal technologies: summary

Published 19 September 2025

Applies to England

1. Chief Scientist’s Group report summary

This project looked at five greenhouse gas removal technologies, assessing their potential environmental and social implications, to improve understanding and identify evidence gaps. This work will help support the Environment Agency, operators, farmers and other organisations to advise on, use, research and regulate these technologies, and will highlight where additional evidence is needed to support the scale-up of these technologies.

1.1 Background

Greenhouse gas removal technologies remove greenhouse gases from the atmosphere. These technologies could form part of the transition to net zero. A concise overview of existing evidence on potential environmental impacts was needed to raise awareness of possible mitigation measures and highlight gaps where further research is required.

Five technologies were selected based on their technological readiness being close to commercial use at scale. These were direct air carbon capture, bioenergy with carbon capture storage (BECCS), biochar, enhanced rock weathering and ocean alkalinity enhancement. Mitigation actions may alleviate some of the potential negative environmental impacts but were not assessed as part of this project. 

1.2 Approach

The project undertook a series of quick scoping reviews of the existing evidence from published scientific and grey literature, with a focus on the potential environmental impacts and social implications of each technology.

1.3 Results

Some of the potential environmental impacts identified include:

• Biomass sources for biochar and BECCS have potential to impact on biodiversity, soil health and flood mitigation depending on crop type and associated land use change. Repurposing biomass waste and residues could divert material from less sustainable management practices e.g. landfill.
• Mining to provide materials for ocean alkalinity enhancement and enhanced rock weathering requires resources (water, land, energy) and has potential environmental impacts e.g. greenhouse gas emissions, deforestation and soil and water contamination.
• Application of biochar or rock dust containing naturally occurring metals or other compounds, could potentially impact soil health, plant growth and water quality.
• Some chemicals used in carbon capture systems and their breakdown products (e.g. nitrosamines), if not assessed and appropriately managed, may negatively impact ozone levels, lead to acidification and eutrophication of water bodies, and pose a potential risk to public health depending on the scale of the emissions.

There is limited social science research on these technologies in the UK. Some parallels on potential implications can be drawn from similar technologies, including change in local workforces, concerns about local impacts, land use changes, and the need for ensuring communities are kept well informed.

Identified evidence gaps include long term impacts of biochar or rock dust application to soils or water, impacts from airborne pollutants on human health, and research on the social implications from the scale-up of these technologies.

1.4 Conclusions

These findings provide underpinning evidence for the anticipated scale-up of greenhouse gas removal technologies. Policymakers and businesses looking to use, produce, or be involved in these technologies may need to consider mitigation strategies to reduce identified potential impacts to the environment or human health. Researchers could use these findings to help address the uncertainties within the evidence gaps identified. This work contributes findings to the evidence-based approach used by the Environment Agency and other organisations.

1.5 Publication details

This summary relates to information from project SC230003, reported in detail in the following outputs:

• Report: SC230003/R1

• Title: Evidence on potential environmental impacts and social implications of greenhouse gas removal technologies – overview report

• Report: SC230003/R2

• Title Bioenergy with carbon capture and storage - evidence on potential environmental impacts

• Report: SC230003/R3

• Title: Review of potential social implications of bioenergy with carbon capture and storage

• Report: SC230003/R4

• Title: Summary report on the potential environmental impacts and social implications of bioenergy with carbon capture and storage

• Report: SC230003/R5

• Title: Biochar - evidence on potential environmental impacts and social implications

• Report: SC230003/R6

• Title: Summary report on the potential environmental impacts and social implications of biochar

• Report: SC230003/R7

• Title: Direct air capture with carbon storage - evidence on potential environmental impacts and social implications 

• Report: SC230003/R8

• Title: Summary report on the potential environmental impacts and social implications of direct air carbon capture and storage

• Report: SC230003/R9

• Title: Enhanced rock weathering - evidence on potential environmental impacts and social implications  

• Report: SC230003/10

• Title: Summary report on the potential environmental impacts and social implications of enhanced rock weathering

• Report: SC230003/11

• Title: Ocean alkalinity enhancement - evidence on potential environmental impacts and social implications 

• Report: SC230003/12

• Title: Summary report on potential environmental impacts and social implications of ocean alkalinity enhancement

• Project manager: Catherine Bayliss, Chief Scientist’s Group

• Research contractors: Eunomia Research & Consulting

This project was commissioned by the Environment Agency’s Chief Scientist’s Group, which provides scientific knowledge, tools and techniques to enable us to protect and manage the environment as effectively as possible.

Enquiries: research@environment-agency.gov.uk.

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