New research calls for the protection of UK saltmarshes | University of St Andrews news ( news.st-andrews.ac.uk )

The UK’s saltmarshes are under threat from climate change, coastal erosion, and sea-level rise, according to a new study led by the University of St Andrews and the University of York.

Occupying more than 450km² of the UK coastline, saltmarshes capture and store large quantities of carbon, which makes them one of the UK’s most important coastal ecosystems. They provide a natural climate regulation service through the long-term storage of organic carbon in their soils.

Year by year, saltmarshes accumulate thin layers of sediments that are rich in carbon from the plants that grow and die there, as well as from adjacent sources on land (via rivers) and at sea. As this organic carbon is buried in the waterlogged soils, decomposition is slowed, keeping carbon out of the atmosphere.

The new study, published in Science of the Total Environment (20 May), follows an assessment of the total amount of saltmarsh carbon in the UK published in 2023. Researchers looked at the density of organic carbon in 21 saltmarshes around the UK, using specialist dating techniques to work out when and how quickly the sediments accumulated. They found that although UK saltmarshes store 5.2 million tonnes of carbon, rates of new carbon accumulation are much slower than expected, and similar to sequestration rates in UK forests.