Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering Sea
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...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2023-01-01
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| Series: | Earth's Future |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2022EF002816 |
| _version_ | 1811176713892134912 |
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| author | Hongjie Wang Darren J. Pilcher Kelly A. Kearney Jessica N. Cross O. Melissa Shugart Matthew D. Eisaman Brendan R. Carter |
| author_facet | Hongjie Wang Darren J. Pilcher Kelly A. Kearney Jessica N. Cross O. Melissa Shugart Matthew D. Eisaman Brendan R. Carter |
| author_sort | Hongjie Wang |
| collection | DOAJ |
| description | 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. |
| first_indexed | 2024-04-10T19:57:23Z |
| format | Article |
| id | doaj.art-a609c00950304a1d973c10714d274463 |
| institution | Directory Open Access Journal |
| issn | 2328-4277 |
| language | English |
| last_indexed | 2024-04-10T19:57:23Z |
| publishDate | 2023-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Earth's Future |
| spelling | doaj.art-a609c00950304a1d973c10714d2744632023-01-27T18:20:32ZengWileyEarth's Future2328-42772023-01-01111n/an/a10.1029/2022EF002816Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering SeaHongjie Wang0Darren J. Pilcher1Kelly A. Kearney2Jessica N. Cross3O. Melissa Shugart4Matthew D. Eisaman5Brendan R. Carter6Graduate School of Oceanography University of Rhode Island Narragansett RI USACooperative Institute for Climate, Ocean, and Ecosystem Studies University of Washington Seattle WA USACooperative Institute for Climate, Ocean, and Ecosystem Studies University of Washington Seattle WA USAPacific Marine Environmental Laboratory National Oceanic and Atmospheric Administration Seattle WA USADepartment of Chemistry and Biochemistry University of South Carolina Columbia SC USADepartment of Electrical and Computer Engineering Stony Brook University Stony Brook NY USACooperative Institute for Climate, Ocean, and Ecosystem Studies University of Washington Seattle WA USAAbstract 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.https://doi.org/10.1029/2022EF002816single point‐source ocean alkalinity enhancement (OAE)electrochemical OAEcarbon dioxide removal (CDR)ocean acidification mitigationBering Seacarbon uptake efficiency |
| spellingShingle | Hongjie Wang Darren J. Pilcher Kelly A. Kearney Jessica N. Cross O. Melissa Shugart Matthew D. Eisaman Brendan R. Carter Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering Sea Earth's Future single point‐source ocean alkalinity enhancement (OAE) electrochemical OAE carbon dioxide removal (CDR) ocean acidification mitigation Bering Sea carbon uptake efficiency |
| title | Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering Sea |
| title_full | Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering Sea |
| title_fullStr | Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering Sea |
| title_full_unstemmed | Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering Sea |
| title_short | Simulated Impact of Ocean Alkalinity Enhancement on Atmospheric CO2 Removal in the Bering Sea |
| title_sort | simulated impact of ocean alkalinity enhancement on atmospheric co2 removal in the bering sea |
| topic | single point‐source ocean alkalinity enhancement (OAE) electrochemical OAE carbon dioxide removal (CDR) ocean acidification mitigation Bering Sea carbon uptake efficiency |
| url | https://doi.org/10.1029/2022EF002816 |
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