A coalition of wildlife charities say stronger protection needs to be given to organic carbon stored in UK seabed habitats. The call follows a landmark new report which has mapped and estimated the amount of carbon naturally stored in the seabed around the UK, including marine protected areas, for the first time. Ironically, it also coincides with the opening of Europe’s first human-made carbon capture projection in Norway aimed at storing liquified CO2 from industrial sources at an offshore location under the seabed in the North Sea.
While the concept of industrial decarbonisation is relatively new, natural carbon deposits on the seabed have been happening for millions of years. They typically occur when phytoplankton, which absorb carbon, drift to the bottom of the sea when they die and add to the existing seabed sediment. Coastal habitats, including saltmarshes, kelp forests and seagrass beds, also store carbon.
Extraction of blue carbon causes risks to the seabed
Compiled by the Scottish Association for Marine Science (SAMS), the blue carbon mapping project charted 114,000 square metres of the UK seabed within the North Sea alone. Examining samples in the top 10cm of sediment, it estimates there are 37.4 million tonnes of organic carbon within that upper layer of what is typically mud, silt and sand.
However, the total amount of stored carbon is much greater as some sediments are hundreds of metres thick and contain millennia’s worth of carbon deposits.
Researchers believe up to 1.27 million tonnes of organic carbon could be added annually where natural sedimentation is able to occur. But they also warn physical disturbances to the seabed, including human activity such as bottom trawling and offshore energy developments, pose a threat to these natural stores by risking the release of large amounts of carbon into the atmosphere and, as a result, worsening climate change.
Now the WWF-UK, the Wildlife Trusts and the RSPB, who commissioned the project, are calling on the government to strengthen protections for so-called blue carbon storage by minimising human impact on the seabed. They point out that most marine protected areas are not designated to protect blue carbon and say disrupting the buried carbon could undermine net zero climate and biodiversity goals.
Preserving and restoring seagrass and saltmarsh habitats
Bex Lynam, marine advocacy manager for the North Seas Wildlife Trusts, said:
“These world-first reports reveal the enormous value of UK seas, including the North Sea. For the first time we are able to fully appreciate the importance of our huge variety of habitat types for carbon storage and sequestration, particularly those unseen beneath the waves like sand and mud, which are often overlooked and yet store 98% of our sequestered organic carbon in the North Sea.
“The North Seas Wildlife Trusts already work closely together as part of wider conservation efforts to restore seagrass and saltmarsh habitats, influence policymakers to designate and manage marine protected areas effectively, and work with relevant bodies to influence fisheries management and developments at sea so they’re undertaken sustainably.
“This research gives the UK an opportunity to lead the world in protecting blue carbon and marine biodiversity, and we hope that policymakers will use this report to recognise the value of blue carbon and work to minimise the impact of human activities on the seabed and on our precious marine habitats, especially in protected areas.”
Blue carbon investment and research
As well as highlighting the risks to the seabed, the report also puts the case for more investment and research on protecting blue carbon. It says more funding should be allocated to restore habitats, including seagrass beds and saltmarshes, as part of the bigger picture while encouraging a “just transition” away from fishing activity which damages the seabed.
Tom Brook, blue carbon specialist at WWF-UK, said:
“This project reveals how critical our seas are in regulating the climate and underscores the urgent need to protect and restore our seabed habitats. While saltmarshes and kelp forests punch above their weight in terms of capturing carbon, the mud really is the star here – accumulating and storing vast amounts on the seabed.
“We need to make sure it goes undisturbed for it to fulfil this critical function by preventing harmful activities such as bottom trawling, starting with our marine protected areas.”
Understanding UK seas is ‘vital’ in protecting blue carbon stores and combatting the climate crisis
Kirsten Carter, head of UK marine policy at the RSPB said: “Accelerating efforts on land to tackle the nature and climate emergency is critical, but we must not underestimate the role of UK seas. This report is a gamechanger for our knowledge of the marine environment and a huge asset for decision-makers. Now we need them to act on its findings.
“To meet net zero and stop biodiversity decline we must work with nature, not against it. This means restoring habitats, properly planning offshore development, and investing in protected areas to safeguard wildlife and keep blue carbon locked up.”
Professor Mike Burrows from SAMS added: “Understanding how much and where our marine carbon is stored is vital for guiding efforts to maintain and protect the capacity of coastal and seabed habitats to continue to serve this function.
“Saltmarshes and seagrass beds are significant carbon storage hotspots, while kelp beds and especially phytoplankton contribute large amounts of organic carbon annually.
“However, the exact fraction of this carbon that is stored in sediments remains uncertain. By consolidating various information sources, we have gained valuable insights into our coastal seabed. This process has also highlighted significant gaps in our knowledge regarding the rates of carbon accumulation in sediments.”
