Rivers: vital allies in tackling climate change
Climate change-related droughts and floods are having a devastating impact on our natural ecosystems. Having healthy, clean rivers, which can act as a natural buffer against these extreme weather events, has never been more important.
While terrestrial ecosystems such as forests usually take the spotlight on climate change debates, rivers are often overlooked in these discussions.
Here, we urge you to keep reading to discover how rivers can help in the fight against climate change…
Carbon sequestration
Rivers play a critical role in regulating the global carbon cycle, acting as conduits that transport decaying organic matter and soil material from land to the ocean, where a part of it sinks to the bottom and is eventually buried and disconnected from the atmosphere for millions of years.
More than regulating carbon, rivers and floodplains also store significant amounts of it. Carbon is stored in above-ground vegetation, soil and within the river channel as drowned wood and vegetation. Peatlands, a type of wetland, store twice as much carbon as forests.

Flood mitigation and drought resilience
River floodplains and wetlands absorb excess water in the events of heavy rainfall, acting as sponges and buffer zones to river swells. At the same time, they slowly release water in dry periods, contributing to drought resilience.
Restoring rivers to their natural state when possible and using natural flood management techniques (NFM), such as reintroducing meanders, building leaky dams, and installing wood deflectors, can significantly decrease flood risks by slowing the flow and making space for water.
Cooling effect in urban landscapes
Rivers and canals help decrease air temperature in cities through evaporation as the water absorbs heat from the air. A 2024 study carried out by the Canal & River Trust and the University of Manchester, showed that the presence of canal water in urban areas can decrease the surrounding temperature by up to 1.6°C. This is especially important to counterbalance the urban heat island effect, in which cities experience higher temperatures than rural areas, and during heat waves. Rivers also act as wind corridors, improving air circulation and distributing the cooling effect.
Biodiversity support
Healthy rivers are biodiversity hotspots. Freshwater ecosystems are among the most diverse on Earth, supporting a range of species in a relatively small area. These species are key in balancing and enabling these ecosystems to adapt to a changing climate and to continue acting as carbon sinks.
Water quality improvement
Clean, healthy rivers provide a vital source of high-quality water, reducing the energy and resources required for treatment and ensuring access to safe drinking water.
Clean freshwater can also help mitigate the impact of high temperatures on freshwater species. High temperatures and pollution both contribute to a decrease in oxygen levels in the water. A joint research conducted by Cardiff University and the University of Vermont showed that an improvement in water quality can offset the impact of warming waters. Dr Ian Vaughan from Cardiff University’s Water Research Institute, commented on an article for the university’s website: “Many freshwater species are very sensitive to temperature, with as little as a 0.5°C increase having large effects. Despite rising temperatures, many rivers in England and Wales have continued to recover from historical pollution problems over recent decades, suggesting that ongoing water quality improvements offset temperature rises.
“For the first time, we have estimated the size of this water quality ‘credit’, which appears to have paid the climatic ‘debt’ accumulated during this period. Although pollution control is not a panacea for the effects of climate change on rivers, our study suggests it is a valuable tool in mitigating effects of climate change in addition to its wider environmental benefits.”

Our rivers are the lifeblood of our planet and offer many ecosystem services besides the ones mentioned above. However, to release their full potential for our and nature’s benefit, they must be healthy. Restoring them to their natural states, using nature-based solutions, and working to eliminate pollution from our waters are essential to tackling climate change and supporting biodiversity.
Elsewhere, we also know that in order to truly improve river environments, we must look at the whole catchment – where the water comes from, its journey through the landscape and what impacts it along the way.
At Thames21, as an environmental charity, we’re committed to restoring London’s rivers and its surrounding natural ecosystems enhancing habitats, improving water quality, reducing flood risks, and empowering communities to protect these vital blue spaces. From constructing wetlands and planting trees to removing barriers and installing in-channel deflectors, our projects build climate-resilient and healthy rivers. But we can’t do it alone. Join us! Volunteer with Thames21 and help us safeguard our rivers for future generations.