Blue carbon as a natural climate solution

Blue carbon ecosystems (BCEs), including mangrove forests, seagrass meadows and tidal marshes, store carbon and provide co-benefits such as coastal protection and fisheries enhancement. Blue carbon sequestration has therefore been suggested as a natural climate solution. In this Review, we examine the potential for BCEs to act as carbon sinks and the opportunities to protect or restore ecosystems for this function. Globally, BCEs are calculated to store >30,000 Tg C across ~185 million ha, with their conservation potentially avoiding emissions of 304 (141–466) Tg carbon dioxide equivalent (CO2e) per year. Potential BCE restoration has been estimated in the range of 0.2–3.2 million ha for tidal marshes, 8.3–25.4 million ha for seagrasses and 9–13 million ha for mangroves, which could draw down an additional 841 (621–1,064) Tg CO2e per year by 2030, collectively amounting to ~3% of global emissions (based on 2019 and 2020 global annual fossil fuel emissions). Mangrove protection and/or restoration could provide the greatest carbon-related benefits, but better understanding of other BCEs is needed. BCE destruction is unlikely to stop fully, and not all losses can be restored. However, engineering and planning for coastal protection offer opportunities for protection and restoration, especially through valuing co-benefits. BCE prioritization is potentially a cost-effective and scalable natural climate solution, but there are still barriers to overcome before blue carbon project adoption will become widespread.

Citation

Macreadie, P. I., Costa, M. D. P., Atwood, T. B., Friess, D. A., Kelleway, J. J., Kennedy, H., … Duarte, C. M. (2021). Blue carbon as a natural climate solution. Nature Reviews Earth & Environment. doi:10.1038/s43017-021-00224-1

Sponsors

The authors acknowledge funding by Deakin University (to P.I.M. and M.D.P.C.), Qantas (to P.I.M. and M.D.P.C.), HSBC (to P.I.M. and M.D.P.C.), Australian Research Council Discovery Grants (DP200100575; to P.I.M. and C.M.D.), King Abdullah University of Science and Technology under KAUST’s Circular Carbon Economy Initiative (to C.M.D.) and the Early Career Research Fellowship from the Gulf Research Program of the National Academies of Sciences, Engineering, and Medicine (to T.B.A.; the content is solely the responsibility of the authors and does not necessarily represent the official views of the Gulf Research Program of the National Academies of Sciences, Engineering, and Medicine). They also thank N. Yilmaz who helped with creation of the figures.