Leveraging Earth Observation to Enhance Blue Carbon MRV: A Rating System for Posidonia Oceanica in Mediterranean Marine Protected Areas

In response to the pressing call for climate action, the International Panel on Climate Change (IPCC) has highlighted the key contribution that carbon dioxide removal will play to counterbalance hard-to-abate residual emissions, alongside efforts to reduce and avoid them.

Coastal blue carbon habitats are responsible for supporting up to 71% of carbon storage in oceanic sediments for centuries, outsizing terrestrial ecosystem carbon storage performances. In the Mediterranean Sea, Posidonia oceanica is not only the most widespread but also the most efficient carbon removal.

Under the Paris Agreement, marine ecosystems have been formally recognized as carbon removal, supporting Parties’ commitments to mitigation. Blue carbon habitats such as Posidonia can be included in compliance carbon crediting systems developed under Article 6 of the Agreement, and they also hold promise within the Voluntary Carbon Market (VCM), where coastal ecosystem credits may be sold as offsets.

Despite this potential, the integration of Posidonia oceanica into carbon markets faces several challenges. For the compliance market under the Paris Agreement, definitions and frameworks are still evolving, while VCM integration is hindered by limited historical data and by the need for affordable, and robust technologies and methodologies to establish a baseline. The definition of a baseline is crucial to set the monitoring period, to measure the activity sustainability and even more to ensure the correct accounting of carbon removal units, by avoiding double counting.

This paper presents how Earth Observation (EO) can support blue carbon removal monitoring, reporting and verification (MRV) through the creation of a rating system. Developed in the framework of the ESA-funded Feasibility Study, “SCORE – Scale for Carbon Organic Resilient Ethereal”, this rating system not only is expected to help Marine Protected Areas (MPA) boost coastal conservation and protection but also provides insights into new business models supported by VCM.