National Seagrass Blue Carbon Accounting in Bahamas using Earth Observation

Kurzfassung

Seagrasses are among the world’s most productive and biodiverse ecosystems, providing a plethora of additional ecosystem services like coastal protection and nursery grounds for fish, amongst other. These ecosystem services are central in national agendas yet countries lack the spatially explicit, high-confidence capacity and data to account and implement them in the aforementioned agendas. The recent Earth Observation advances, including cloud computing, artificial intelligence and dense satellite data acquisitions, in combination with field data can provide a contemporary scalable technological solution to physically and financially account seagrass and coastal ecosystem services in a time and cost-efficient fashion. Here, we present a novel scalable Earth Observation framework within the cloud platform of the Google Earth Engine to account the ecosystem services of seagrasses in The Bahamas, across 114,059 km2. Leveraging over 18,000 of 10-m Sentinel-2 satellite images and thousands of country-aggregated biophysical data, we account the physical ecosystem extent of Bahamian seagrasses between 39,799-47,344 km2, only second to Australian seagrass extent, globally. Regarding seagrass ecosystem carbon storage and sequestration rate, we account between 613,607,864 to 780,541,162 Mg C, between 105 to 125 Mt CO2 per year, respectively. This equals 58 to 69 times the CO2 emissions of The Bahamas in 2018, potentially rendering a carbon-neutral state and underlining the importance of seagrasses for Bahamian climate agendas. We also showcase the application of the said Bahamian seagrass extent to physically and monetary account bundles of ecosystem services of these extensive seagrasses, including coastal protection and coastal biodiversity. We envisage that the synergy between our scalable Earth Observation framework and nation-specific in-situ observations can support spatially-explicit ecosystem service accounting, and effective uptake in relevant policy making and financial investments for seagrasses in and beyond The Bahamas.