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Testing the climate intervention potential of ocean afforestation using the Great Atlantic Sargassum Belt


Bach, LT and Tamsitt, V and Gower, J and Hurd, CL and Raven, JA and Boyd, PW, Testing the climate intervention potential of ocean afforestation using the Great Atlantic Sargassum Belt, Nature Communications, 12, (1) Article 2556. ISSN 2041-1723 (2021) [Refereed Article]

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The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

DOI: doi:10.1038/s41467-021-22837-2


Ensuring that global warming remains <2 C requires rapid CO2 emissions reduction. Additionally, 100900 gigatons CO2 must be removed from the atmosphere by 2100 using a portfolio of CO2 removal (CDR) methods. Ocean afforestation, CDR through basin-scale seaweed farming in the open ocean, is seen as a key component of the marine portfolio. Here, we analyse the CDR potential of recent re-occurring trans-basin belts of the floating seaweed Sargassum in the (sub)tropical North Atlantic as a natural analogue for ocean afforestation. We show that two biogeochemical feedbacks, nutrient reallocation and calcification by encrusting marine life, reduce the CDR efficacy of Sargassum by 20100%. Atmospheric CO2 influx into the surface seawater, after CO2-fixation by Sargassum, takes 2.518 times longer than the CO2-deficient seawater remains in contact with the atmosphere, potentially hindering CDR verification. Furthermore, we estimate that increased ocean albedo, due to floating Sargassum, could influence climate radiative forcing more than Sargassum-CDR. Our analysis shows that multifaceted Earth-system feedbacks determine the efficacy of ocean afforestation.

Item Details

Item Type:Refereed Article
Keywords:ocean afforestation, seaweed farming, climate intervention, albedo
Research Division:Earth Sciences
Research Group:Oceanography
Research Field:Biological oceanography
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Mitigation of climate change
Objective Field:Management of greenhouse gas emissions from plant production
UTAS Author:Bach, LT (Dr Lennart Bach)
UTAS Author:Hurd, CL (Professor Catriona Hurd)
UTAS Author:Boyd, PW (Professor Philip Boyd)
ID Code:144626
Year Published:2021
Web of Science® Times Cited:26
Deposited By:Ecology and Biodiversity
Deposited On:2021-05-31
Last Modified:2022-08-24
Downloads:19 View Download Statistics

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