2023-06-23 09:30:12
After more than a year of development, the Ministry of Ecological Transition validates the first “low carbon” labeling methodology dedicated to the preservation of seagrass beds in metropolitan France. A first pilot project will soon be deployed on the Posidonia meadows of the Calanques National Park.
Seagrasses are of definite interest in terms of carbon storage and the development of biodiversity. In the world, they represent 2% of the total surface of the oceans, but are home to 4 to 18% of marine species. They would also store 3 to 5 times more carbon than a tropical forest and up to 7 times more than a French hardwood forest, according to EcoAct, a subsidiary of Atos, specializing in decarbonization strategy. But “we have lost about 10% of their surface in the Mediterranean basin in the last 100 years”, shares Jeanne Barreyre, expert in biodiversity issues at EcoAct within the “research and innovation” team. And the average regression rate of Posidonia meadows in France is estimated at 0.29% per year on average, mainly due to boat anchors.
To better protect this species, EcoAct joined forces with Digital Realty, Schneider Electric France and the Calanques National Park in March 2021 to develop the first methodology for the preservation of Posidonia meadows in the French Mediterranean. Approved by the Directorate General for Energy and Climate (DGEC) of the Ministry for Ecological and Solidarity Transition (MTES) in April 2023, this methodology will allow the certification of projects in France via the low carbon label. And there is plenty to do: the French Mediterranean has 80,000 hectares of seagrass beds, spread over the southern Provence-Alpes-Côte d’Azur, Occitanie and Corsica regions.
A reduction of up to 700,000 tonnes of CO equivalent2 over 30 years
“What is called Posidonia herbarium is in fact made up of two parts: the plant, itself made up of stems – or rhizomes –, bundles, leaves and roots, and the matte, made up of dead rhizomes, of roots and sediments », explains Jeanne Barreyre. Plants store little carbon. “It is this matte that stores the most carbon and must therefore be protected from the anchoring of boats to ensure sequestration”she continues.
By default, EcoAct assesses the carbon stocks to be protected at 327 tonnes per hectare of Posidonia meadows. To assess the reduction potential associated with future projects, “we estimated the degradation due to the anchoring of the boats which has two mechanical effects: regression on the surface by tearing the beams, and the decomposition in depth of the matte by dint of anchoring in the same place”, says Jeanne Barreyre. EcoAct thus assesses the potential for reducing carbon emissions across the entire French Mediterranean area, thanks to the protection of seagrass beds in front of anchorages, at 24,000 tonnes of CO equivalent.2 per year. This offers an overall potential of around 700,000 tonnes over 30 years, the duration of future projects.
A first project for the Calanques National Park
The finalization of the first project resulting from this methodology with the Calanques National Park is underway for a planned launch by 2025. “We are in the process of defining the actions to be put in place to protect the 100 hectares of meadows spread over the 700 hectares of the project, and defining the associated monitoring costs over 30 years”, shares Jeanne Barreyre.
If the usual prices per tonne of carbon associated with low-carbon label projects are on average 40 euros per tonne of carbon, we will still have to wait a little longer to know the price per tonne of carbon avoided for future projects associated with this methodology. “The cost here will strongly depend on the surface area of the meadows to be protected and the cost of the actions implemented for each project”explains Jeanne Barreyre.
In concrete terms, what form does the protection of seagrass take? The methodology proposes a list of eligible projects. These projects include “any activity that will limit anchorage, regulate the number of boats or their location”summarizes Jeanne Barreyre. “This may be the banning of anchoring, the installation of buoys to which boats cling rather than dropping their anchors on the seabed, the installation of mooring areas and light equipment, or even the financing of the surveillance of anchorage areas. »
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