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© 2023. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Ocean alkalinity enhancement (OAE) has the potential to mitigate ocean acidification (OA) and induce atmospheric carbon dioxide (CO2) removal (CDR). We evaluate the CDR and OA mitigation impacts of a sustained point-source OAE of 1.67 × 1010 mol total alkalinity (TA) yr−1 (equivalent to 667,950 metric tons NaOH yr−1) in Unimak Pass, Alaska. We find the alkalinity elevation initially mitigates OA by decreasing pCO2 and increasing aragonite saturation state and pH. Then, enhanced air-to-sea CO2 exchange follows with an approximate e-folding time scale of 5 weeks. Meaningful modeled OA mitigation with reductions of >10 μatm pCO2 (or just under 0.02 pH units) extends 100–100,000 km2 around the TA addition site. The CDR efficiency (i.e., the experimental seawater dissolved inorganic carbon (DIC) increase divided by the maximum DIC increase expected from the added TA) after the first 3 years is 0.96 ± 0.01, reflecting essentially complete air-sea CO2 adjustment to the additional TA. This high efficiency is potentially a unique feature of the Bering Sea related to the shallow depths and mixed layer depths. The ratio of DIC increase to the TA added is also high (≥0.85) due to the high dissolved carbon content of seawater in the Bering Sea. The air-sea gas exchange adjustment requires 3.6 months to become (>95%) complete, so the signal in dissolved carbon concentrations will likely be undetectable amid natural variability after dilution by ocean mixing. We therefore argue that modeling, on a range of scales, will need to play a major role in assessing the impacts of OAE interventions.

Details

Title
Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering Sea
Author
Wang, Hongjie 1   VIAFID ORCID Logo  ; Pilcher, Darren J 2   VIAFID ORCID Logo  ; Kearney, Kelly A 3   VIAFID ORCID Logo  ; Cross, Jessica N 4 ; Shugart, O Melissa 5 ; Eisaman, Matthew D 6 ; Carter, Brendan R 2   VIAFID ORCID Logo 

 Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, USA 
 Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA, USA; Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, WA, USA 
 Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA, USA; Alaska Fisheries Science Center, National Oceanic and Atmospheric Administration, Seattle, WA, USA 
 Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, WA, USA 
 Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, USA 
 Department of Electrical and Computer Engineering, Stony Brook University, Stony Brook, NY, USA 
Section
Research Article
Publication year
2023
Publication date
Jan 2023
Publisher
John Wiley & Sons, Inc.
e-ISSN
23284277
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2770083518
Copyright
© 2023. This work is published under http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.