Study re-evaluates long-term burial rates of carbon in Irish Sea sediments

Scientists have uncovered new evidence that reveals the role of muddy seabeds in carbon storage in the Irish Sea, which may support long-term climate regulation. 

A recent study led by the National Oceanography Centre (NOC) reveals that the Western Irish Sea Mud Belt (WISMB) locks away organic carbon for hundreds of years, offering novel empirical evidence of prolonged carbon storage in these shelf sea sediments. 

The findings, published in the Journal of Geophysical Research: Biogeosciences, provide crucial insights and robust data that can help to guide evidence-based blue carbon strategies and strengthen global understanding of how shelf seas contribute to carbon storage and climate change mitigation. 

It’s one of the first studies to provide age- and depth-resolved sedimentary carbon storage data in this region and fills in a key knowledge gap for research in this field. 

Dr. Hannah Muir, Applied Scientist at NOC and one of the lead researchers, said: “Understanding how much organic carbon (OC) is buried in the seabed over time is vital for estimating the role of shelf seas in climate regulation, but it is also challenging as it requires knowledge of sediment age, as well as how much OC it stores. 

“Many studies only analyse the surface sediments, but the novelty of our study is we analysed carbon stored 50 cm into the seabed. By comparing the OC density in younger surface sediments with older, deeper sediments, we showed that long-term OC burial, for over a century, is around a third lower than OC accumulated in the top 10 cm, in the first four decades. What this means is that by looking only at surface sediments, we may miss key information about changes in OC storage over time, which we need to provide an accurate assessment of the potential climate regulating function of our shelf seas. Looking deeper into sediments overcomes this limitation. 

“The amount of OC stored in the WISMB is similar to other muddy areas, such as coastal fjords and glacial troughs, which highlights how important areas like the WISMB are for storing OC long-term.” 

Dr. Muir presented the report’s findings at a community event on Wednesday 25 March, attended by representatives from the Isle of Man Government including Honourable Clare Barber MHK, Minister for the Department of Environment, Food and Agriculture. 

Dr. Muir added: “This was an important chance to showcase some of NOC’s world-leading research on blue carbon and to return it to the community, reflecting our commitment to generating meaningful and impactful research.” 

The research was conducted by NOC as part of the Manx Blue Carbon Project, working in partnership alongside the Isle of Man Government (project funder and co-lead), Swansea University, Bangor University, University of Southampton, and Manx Wildlife Trust. 

Clare Barber MHK, Minister for Environment, Food and Agriculture, said: “The Manx Blue Carbon Project has shown just how important our seas are, not only for wildlife and fisheries, but also for tackling climate change. This research, including the report and supporting papers, gives us the evidence we need to protect our marine environment wisely, support sustainable economic opportunities, and ensure these benefits endure.”