Exploring marine habitat restoration opportunities and blue carbon sequestration potential in the United Kingdom

Nature-based solutions (NbS), including blue carbon ecosystems, are crucial to meeting Net-Zero targets. The UKs Net-Zero 2050 strategy, alongside terrestrial measures, prioritises large-scale offshore wind development, creating opportunities to integrate marine NbS into Net-Zero plans. Consequently, aligning decarbonisation targets with conservation goals demands marine spatial planning and adaptive Marine Protected Area (MPA) networks. While estimates suggest UK marine systems store [~]244 million tonnes of organic carbon, sequestration potentials remain poorly quantified. We developed marine spatial plans for the UK and estimated carbon sequestration potentials. We divided the UK Exclusive Economic Zone into four zones (Open, Conservation, Oil, and Energy) using Marxan with Zones under two scenarios: (1) Existing MPAs locked-in, and (2) Unconstrained. Conservation Zones were defined as regions with minimal human activity. Planning incorporated 14 features: four species distribution models (SDMs), including the first UK-wide maerl SDMs, habitat suitability maps for subtidal macroalgae, and relevant stakeholder maps, such as offshore wind and oil fields. Conservation zones overlapped with >70% of current MPAs and complemented them by isolating biodiversity from anthropogenic activities, such as ports, without compromising renewable energy targets. We estimated sequestration rates of 533 - 625 kt C yr-1, with restoration contributing an additional 0.11 - 0.12 kt C yr-1 by 2040. These results provide evidence for embedding marine NbS into national strategies such as the UK Marine Strategy, while highlighting the need to address gaps in marine carbon dynamics to enable effective spatial planning and alignment with voluntary carbon markets to bridge climate finance gaps.