Recent research underscores the critical importance of saltmarshes as significant carbon stores, particularly in the context of rising sea levels and climate change. A collaborative report from the conservation charity WWF, in partnership with insurance giant Aviva, highlights these coastal ecosystems’ vital role in reducing greenhouse gases and safeguarding coastal communities.

Utilising a solar-powered “carbon flux tower” on the Ribble Estuary in Lancashire, the research measures the exchange of carbon dioxide—one of the key greenhouse gases—between the air and the saltmarshes. This technique, already employed in forests and peatlands, marks a novel application in saltmarshes, providing the first insights from a newly established network of measurement towers across the UK. Findings indicate that, despite seasonal fluctuations, saltmarshes generally act as a net sink for carbon dioxide, absorbing more carbon in warmer months than they release in winter.

The WWF and Aviva are advocating for the inclusion of saltmarshes in the UK’s official greenhouse gas inventory. They posit that recognising the carbon sequestration capabilities of these habitats could enhance national reporting, thereby unlocking crucial funding and policy initiatives dedicated to their protection and restoration. Currently, a staggering 85% of the UK’s saltmarshes have been lost since the mid-19th century, diminishing both their ecological and protective benefits. The remaining saltmarshes are vital for shielding over £200 billion in assets across England and Wales from the threats posed by rising sea levels and storm surges.

In response to the pressing issue of climate change, the research also involved a network of surface elevation tables across six UK saltmarshes to track changes in their height relative to rising sea levels. Results suggest that while many saltmarshes are managing to gain height—particularly in areas like Chichester and The Wash—some regions, including North Norfolk and parts of the Ribble Estuary, are exhibiting signs of distress.

Tom Brook, ocean conservation specialist at WWF, emphasised the urgency of the situation: “The results are in, and mud matters. Saltmarshes are powerful natural allies in the fight against climate change—storing carbon, protecting our coasts, and supporting rich biodiversity. As extreme weather and rising sea levels put more people and places at risk, the case for protecting and restoring these habitats has never been stronger.”

Saltmarshes not only sequester carbon through the process of photosynthesis and storing it in biomass, but they also play a crucial role in coastal protection by dissipating wave energy and reducing erosion. Studies indicate that a single hectare of saltmarsh can sequester approximately two tonnes of carbon annually, with undisturbed marshes capable of retaining these carbon stores for centuries.

However, threats loom large as nearly 100 hectares of saltmarsh are lost each year due to drainage, coastal development, and the pressures of climate change. Additionally, while it’s been shown that rising sea levels can enhance the carbon storage capacity of coastal wetlands through sediment capture and the thickening of root materials, there is still a considerable need for protective measures to maintain these vital ecosystems.

Investments are starting to emerge, with the UK Centre for Ecology and Hydrology leading a partnership that aims to secure £1 billion for restoring degraded saltmarshes across England. Such restoration projects involve reintroducing tidal flows to previously reclaimed lands to reinstate natural processes and functions vital for these habitats’ sustainability.

With current research estimating that UK saltmarshes store an impressive 5.2 million tonnes of carbon, the emphasis on protecting these ecosystems becomes increasingly significant. As studies reveal that new carbon accumulation rates may be slower than anticipated, comparable to those found in UK forests, it becomes clear that immediate action is essential to safeguard these reserves and their contributions to climate change mitigation.

In light of these findings, the push for greater recognition of saltmarshes in carbon accounting frameworks and increased investment in their restoration could pave the way for both ecological resilience and enhanced climate action, aligning with broader efforts toward a sustainable, net-zero future.

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Source: Noah Wire Services