Landmark report quantifies carbon in UK seabeds

ITV News Science Correspondent Martin Stew followed scientists in Yorkshire who map marine carbon stores

Conservationists call for the better protection of the UK's marine habitats as the capacity to store carbon under the sea has been mapped for the first time.

The new "blue carbon" report estimates the UK seabed could absorb up to 13 million tonnes of carbon every year, almost three times more than the UK's forests, thought they cover much smaller area than the sea.

The report by the Scottish Association for Marine Science (SAMS) on behalf of WWF, The Wildlife Trusts and the RSPB is the first time a country has estimated and mapped its marine carbon stores.

It estimates there is 244 million tonnes of organic carbon locked up in 10 cm of seabed sediments and coastal habitats such as saltmash, kelp and seagrass beds.

Of the total carbon stored, 98% can be found in the top layer of the seabed sediments but it adds that some sediments are hundreds of metres thick, storing thousands of years’ worth of carbon, so it is thought that their true storage is much greater.

The remaining carbon is found in coastal habitats such as saltmarshes around the coasts of England and Wales.

While these coastal regions only make up 1% of the UK seas, the report says areas "punch above their weight" as they store 1.7% of the oceans carbon.

Marine protected areas (MPAs), which are already designated for nature protection, store more than two-fifths of organic carbon, 105 million tonnes, estimated to be in long-term storage in the seas.

Carbon is primarily absorbed by tiny plant-like organisms known as phytoplankton, which capture carbon dioxide through photosynthesis and drift to the bottom of the sea when they die, adding to the seabed sediment.

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However, experts warn that disturbance to the seabed by humans activities such as bottom trawling with fishing gear and the installation of offshore energy such as wind farms, could release the stored carbon worsening climate change.

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.

“But we need to make sure it goes undisturbed for it to fulfil this critical function. Harmful activities such as bottom trawling must be stopped.”

A spokesperson for the Environment Department (Defra) said: “Protecting our oceans, and the precious species that depend on them, is fundamental to a healthy and thriving environment.

“We will ratify a new Global Oceans Treaty to protect marine life, enforce bottom trawling restrictions in our Marine Protected Areas and ensure all catch limits are set sustainably.”

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