Seagrass meadows could play a greater role in climate change mitigation than previously recognised, with a new study highlighting their significant carbon storage and absorption capacity.
Researchers in Spain analysed global data on seagrass structure, biomass and net primary productivity (NPP) to assess their contribution to the carbon cycle.
They estimate that seagrass stores between 24 million and 40 million tonnes of carbon globally, while its NPP captures a further 83 million to 137 million tonnes of carbon each year.
The study also found differences between regions and species. Posidonia seagrass was estimated to hold up to 50 times more carbon biomass than Halophila, while the Mediterranean had the highest carbon stock per hectare.
The researchers say this makes the Mediterranean a particularly important area for targeted conservation and restoration.
Australia was estimated to account for 52% of global CO₂ emissions from seagrass loss, followed by Spain, Mexico, Italy and the US.
The findings suggest that long-lived seagrass species should be considered in carbon accounting, provided conservation and restoration efforts maintain existing carbon stores.
However the researchers warn that measuring seagrass carbon stocks remains challenging because storage varies significantly between locations and over time.
The study still provides substantially improved data, including an estimated 91% increase in seagrass biomass information, which could help inform future blue carbon and climate mitigation strategies.
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