As the need for more nature-based climate solutions grows, blue carbon has become widely recognized for its burgeoning potential in the carbon offset market space. Blue carbon is a term used to describe organic carbon storage and sequestration within the plants and soils of coastal environments [1]. Mangrove forests, seagrass meadows, and tidal marshes represent some of the world’s most important carbon sinks due to their irreplaceable mix of ecosystem services, climate change resilience, and carbon storage capabilities. Unfortunately, these valuable ecosystems are also some of our most threatened habitats. Mangrove forests are being lost at a rate of 2% per year [2] usually from deforestation for aquaculture ponds, land use change, and human development [3]. Aside from supporting marine biodiversity and a plethora of other co-benefits, these coastal ecosystems are also important natural barriers to rising seas and storm surges brought on by increasingly severe weather patterns.
It’s no secret that marine environments sequester a lot of carbon. A 2019 report from the High Level Panel for a Sustainable Ocean Economy estimates that conserving these coastal ecosystems could provide annual emissions reductions of up to 1.4GtCO2e globally by 2050 [4]. In fact, mangrove forests alone account for 10-15% of coastal carbon sequestration, despite only occupying 0.5% of total coastal ecosystems area. Mangrove soils and sediments also sequester carbon at a rate about 20 times greater than that of terrestrial forest ecosystems [5] making them strong candidates for carbon offsets. Yet the opportunity for mangrove forests to infiltrate carbon markets brings with it some unique challenges. Sea level rise for example poses an obvious concern where mangrove restoration must adapt to projections of disappearing coastlines. Meanwhile other biological and biogeochemical processes combined with anthropogenic disturbances influence rates of blue carbon burial across different regions [3]. Carbon stored within coastal soils and sediments originates from both autochthonous (produced on-site) and allochthonous (transported from elsewhere) sources, with large variability in allochthonous deposition depending on the hydrodynamic nature of a given area [6]. Examples like this explain why developing standards for blue carbon projects has been difficult to justify both scientifically and economically, but this shouldn’t discourage future endeavors.
Active groups like The Blue Carbon Initiative, the IUCN, and the Verified Carbon Standard have recently taken on initiatives to develop blue carbon projects, simultaneously growing excitement among the markets supporting them. With several mangrove restoration projects now underway or in the development process, the potential for blue carbon credits to incentivize more coastal conservation programs and carbon sequestration is the win-win scenario we certainly hope to see.
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