Research and analysis

How will climate change shape the impacts of invasive freshwater species in England: summary

Published 13 October 2026

Applies to England

1. Chief Scientist’s Group report summary

This project examined how climate change may affect the impacts of invasive non-native species (INNS) in England’s freshwater environments up to 2100. It combined evidence from published research with expert knowledge to understand how changing environmental conditions may influence the establishment, spread and impacts of invasive species. The findings will help the Environment Agency and others anticipate future risks, improve planning and better protect freshwater ecosystems.

1.1 Background

INNS are already a major pressure affecting freshwater ecosystems in England. They can reduce biodiversity, affect water quality, disrupt ecosystem processes and increase costs for infrastructure operators and land managers.

Climate change is expected to alter rivers, lakes and wetlands through warmer temperatures and changes in rainfall patterns leading to more frequent floods, droughts and other extreme weather events. These changes are likely to influence both the suitability of habitats for INNS and the pathways through which they spread, increasing the vulnerability of freshwater ecosystems to invasion and placing additional pressures on native plants and animals. Understanding how climate change and INNS interact is therefore important for protecting biodiversity, protecting water quality and ensuring that freshwater ecosystems continue to provide benefits for people and wildlife.

1.2 Approach

The project involved a high-level review of scientific literature on climate change and freshwater invasions. It considered physical drivers such as temperature change, flooding and drought; ecological drivers such as species interactions and ecosystem resilience; and human drivers such as water transfers, reservoirs, flood management infrastructure and recreation. Expert input was used to help identify future risks, develop conceptual frameworks and highlight priorities for future research.

1.3 Results

The review found that climate change is likely to increase the risk and impacts of many freshwater INNS. Where species are currently restricted by temperature, warmer temperatures and in particular milder winters may allow some species to expand their range and increase in abundance. Longer growing seasons for plants and more frequent disturbance from extreme weather events may favour INNS over native species in some locations.

Flooding may increase the movement of INNS between waterbodies. Drought may weaken native communities and create conditions that favour INNS that can tolerate disturbance. Some ornamental and traded species that are not currently considered invasive may become problematic under future climate conditions.

The review also found that likely human responses to climate change could unintentionally create new opportunities for spreading INNS. Changes to water resource infrastructure, increased connectivity between catchments and greater recreational use of freshwater environments could all increase invasion risks. These pressures are likely to interact, making future invasions more difficult and costly to manage.

Early action and prevention – such as banning the sale and movement of high-risk species – remain the best value responses. Horizon scanning of potential INNS, strong biosecurity to prevent spreading INNS, targeted monitoring, rapid response to invasions and bio-controls and can reduce the likelihood that new invasions become established and costly.

1.4 Conclusions

Climate change is likely to increase the challenges posed by freshwater INNS in England. Both environmental change and human adaptation measures may contribute to greater opportunities for species establishment and spread. The findings provide a framework for understanding how future risks may develop, how the risks can be reduced and identify priorities for research and surveillance. They will help the Environment Agency and others improve preparedness, target resources effectively and support the long-term resilience of England’s freshwater environments.

1.5 Publication details

This summary relates to information from project SC250021, reported in detail in the following output:

• Title: How will climate change shape the impacts of invasive freshwater species in England?
• Science manager: Judy England, Chief Scientist’s Group
• Research Contractor: David Aldridge, Cambridge Environmental Consulting, Barrances, 49 Caxton End, Bourn, Cambridgeshire, CB23 2SS.

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.

© Environment Agency