Potential impacts of marine carbon dioxide removal on ocean oxygen

Global warming is a main cause for current ocean deoxygenation. A deployment of marine carbon dioxide removal (CDR) for mitigating global warming could therefore also be viewed as a measure for mitigating ocean deoxygenation if, and only if, the respective CDR measure itself does not lead to a large...

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Main Authors: Andreas Oschlies, Caroline P Slomp, Andrew H Altieri, Natalya D Gallo, Marilaure Gregoire, Kirsten Isensee, Lisa A Levin, Jiajun Wu
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:Environmental Research Letters
Subjects:
Online Access:https://doi.org/10.1088/1748-9326/ade0d4
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author Andreas Oschlies
Caroline P Slomp
Andrew H Altieri
Natalya D Gallo
Marilaure Gregoire
Kirsten Isensee
Lisa A Levin
Jiajun Wu
author_facet Andreas Oschlies
Caroline P Slomp
Andrew H Altieri
Natalya D Gallo
Marilaure Gregoire
Kirsten Isensee
Lisa A Levin
Jiajun Wu
author_sort Andreas Oschlies
collection DOAJ
description Global warming is a main cause for current ocean deoxygenation. A deployment of marine carbon dioxide removal (CDR) for mitigating global warming could therefore also be viewed as a measure for mitigating ocean deoxygenation if, and only if, the respective CDR measure itself does not lead to a larger oxygen loss than the reduction in atmospheric CO _2 would prevent. We here review the current state of knowledge regarding the potential impacts of various marine CDR (mCDR) options onto ocean oxygen, a key ocean state variable and an essential element for all higher forms of marine life. Using results from global model simulations, we show that biotic approaches, such as ocean fertilization, macroalgae cultivation and sinking, and placement of organic matter that is prone to remineralization, can lead to a loss in seawater dissolved oxygen that is 4–40 times larger than the oxygen gain that would result from the CDR-induced reduction in global warming only. Biotic approaches also tend to enhance the amplitude of the diel cycle in dissolved oxygen, with possible physiological impacts specifically in shallow-water environments of coastal vegetated ecosystem. In contrast, geochemical approaches, and biotic approaches that avoid remineralization of biomass within the ocean, may be applied in ways that have minimal impacts on dissolved oxygen. We suggest that impacts on marine oxygen should be accounted for in assessing the suitability of mCDR, and that oxygen should be measured prior to, during and after any research-scale or full-scale implementation activity.
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spelling doaj-art-756d0a8d0bfe4980a0af8cc4f89aca8b2025-08-20T03:44:51ZengIOP PublishingEnvironmental Research Letters1748-93262025-01-0120707300210.1088/1748-9326/ade0d4Potential impacts of marine carbon dioxide removal on ocean oxygenAndreas Oschlies0https://orcid.org/0000-0002-8295-4013Caroline P Slomp1Andrew H Altieri2Natalya D Gallo3https://orcid.org/0000-0001-5168-4244Marilaure Gregoire4Kirsten Isensee5Lisa A Levin6Jiajun Wu7https://orcid.org/0000-0002-0084-4866GEOMAR Helmholtz Centre for Ocean Research Kiel , Wischhofstr. 1-3, 24148 Kiel, Germany; Kiel University , Christian-Albrechts-Platz 4, 24118 Kiel, GermanyRadboud Institute for Biological and Environmental Research, Radboud University , Nijmegen, The NetherlandsDepartment of Environmental Engineering Sciences, University of Florida , Gainesville, FL, United States of AmericaNorwegian Research Centre (NORCE) and the Bjerknes Centre for Climate Research , Bergen, Norway; Department of Biological Sciences, University of Bergen , Bergen, NorwayMAST-FOCUS, Astrophysics, Geophysics and Oceanography Department, Liège University , Liège, BelgiumIntergovernmental Oceanographic Commission (IOC) of UNESCO , 7 Place de Fontenoy, 75007 Paris, FranceCenter for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego , La Jolla, CA, United States of AmericaInstitute of Oceanography, University of Hamburg , Bundesstrasse 55, 20146 Hamburg, GermanyGlobal warming is a main cause for current ocean deoxygenation. A deployment of marine carbon dioxide removal (CDR) for mitigating global warming could therefore also be viewed as a measure for mitigating ocean deoxygenation if, and only if, the respective CDR measure itself does not lead to a larger oxygen loss than the reduction in atmospheric CO _2 would prevent. We here review the current state of knowledge regarding the potential impacts of various marine CDR (mCDR) options onto ocean oxygen, a key ocean state variable and an essential element for all higher forms of marine life. Using results from global model simulations, we show that biotic approaches, such as ocean fertilization, macroalgae cultivation and sinking, and placement of organic matter that is prone to remineralization, can lead to a loss in seawater dissolved oxygen that is 4–40 times larger than the oxygen gain that would result from the CDR-induced reduction in global warming only. Biotic approaches also tend to enhance the amplitude of the diel cycle in dissolved oxygen, with possible physiological impacts specifically in shallow-water environments of coastal vegetated ecosystem. In contrast, geochemical approaches, and biotic approaches that avoid remineralization of biomass within the ocean, may be applied in ways that have minimal impacts on dissolved oxygen. We suggest that impacts on marine oxygen should be accounted for in assessing the suitability of mCDR, and that oxygen should be measured prior to, during and after any research-scale or full-scale implementation activity.https://doi.org/10.1088/1748-9326/ade0d4carbon dioxide removalocean oxygenimpact assessment
spellingShingle Andreas Oschlies
Caroline P Slomp
Andrew H Altieri
Natalya D Gallo
Marilaure Gregoire
Kirsten Isensee
Lisa A Levin
Jiajun Wu
Potential impacts of marine carbon dioxide removal on ocean oxygen
Environmental Research Letters
carbon dioxide removal
ocean oxygen
impact assessment
title Potential impacts of marine carbon dioxide removal on ocean oxygen
title_full Potential impacts of marine carbon dioxide removal on ocean oxygen
title_fullStr Potential impacts of marine carbon dioxide removal on ocean oxygen
title_full_unstemmed Potential impacts of marine carbon dioxide removal on ocean oxygen
title_short Potential impacts of marine carbon dioxide removal on ocean oxygen
title_sort potential impacts of marine carbon dioxide removal on ocean oxygen
topic carbon dioxide removal
ocean oxygen
impact assessment
url https://doi.org/10.1088/1748-9326/ade0d4
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