National Ecosystem Accounting of Seagrass Extent, Blue Carbon Stocks and Sequestration Potentials in The Bahamas harnessing contemporary Earth Observation advances

Kurzfassung

Seagrasses offer a wide range of ecosystem services, heralded as natural climate solutions, which are fundamental for sustaining the wellbeing and resilience of humans and the natural environment. These vegetated coastal foundation organisms are one of the world’s most productive ecosystems and play an important yet often overlooked and underassessed role in climate change mitigation and adaptation, biodiversity maintenance, and coastal protection from ext reme weather events. Their carbon sequestration and storage potential can support a variety of Multilateral Environmental Agreements like the Nationally Determined Contributions of the Paris Agreement, the EU Green Deal, and the Sustainable Development Goals. Standardized, comprehensive and spatially explicit knowledge of national seagrass extent and ecosystem services is crucial for meticulous seagrass ecosystem accounting. Within the Global Seagrass Watch project, funded by the German Aerospace Center (DLR) and supported by the Group on Earth Observations-Google Earth Engine program, we processed 18,881 single images to create a multi-temporal Sentinel-2 composite using the cloud computing platform Google Earth Engine to quantify the seagrass extent, and associated carbon stocks and sequestration rates for Bahamian waters. Preliminary results yield a seagrass extent larger than the land area of The Bahamas, which can store approximately 1,101 Mt CO2, and sequester 26 times more CO2 than annually emitted by the country. However, only about 11% of the Bahamian seagrass area lies within Marine Protected Areas. Our generated national data inventories underline the necessity of implicating seagrass blue carbon into national climate agendas and showcase the need for stronger and more cost-effective conservation and restoration efforts for seagrass meadows. Moreover, our data and technology can help to estimate the economic value of Bahamian seagrasses and their ecosystem services, demonstrating the importance of Earth Observation applications for ecosystem accounting frameworks like the System of Environmental-Economic Accounting (SEEA) - Ecosystem Accounting. We envisage that integrating Earth Observation into biophysical modelling could support holistic solutions for climate change mitigation, marine spatial planning, and biodiversity research within and beyond The Bahamas.