Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022
<p>The Bering Sea shelf supports a highly productive marine ecosystem that is vulnerable to ocean acidification (OA) due to the cold, carbon-rich waters. Previous observational evidence suggests that bottom waters on the shelf are already seasonally undersaturated with respect to aragonite (i....
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Copernicus Publications
2025-07-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/22/3103/2025/bg-22-3103-2025.pdf |
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| author | D. J. Pilcher D. J. Pilcher J. N. Cross J. N. Cross N. Monacci L. Mu K. A. Kearney K. A. Kearney A. J. Hermann A. J. Hermann W. Cheng W. Cheng |
| author_facet | D. J. Pilcher D. J. Pilcher J. N. Cross J. N. Cross N. Monacci L. Mu K. A. Kearney K. A. Kearney A. J. Hermann A. J. Hermann W. Cheng W. Cheng |
| author_sort | D. J. Pilcher |
| collection | DOAJ |
| description | <p>The Bering Sea shelf supports a highly productive marine ecosystem that is vulnerable to ocean acidification (OA) due to the cold, carbon-rich waters. Previous observational evidence suggests that bottom waters on the shelf are already seasonally undersaturated with respect to aragonite (i.e. <span class="inline-formula">Ω<sub>arag</sub><1</span>) and that OA will continue to increase the spatial extent, duration, and intensity of these conditions. Here, we use a regional ocean biogeochemical model to simulate changes in ocean carbon chemistry for the Bering Sea shelf from 1970–2022. Over this timeframe, model results suggest that surface <span class="inline-formula">Ω<sub>arag</sub></span> decreases by <span class="inline-formula">−0.043</span> per decade and surface pH by <span class="inline-formula">−0.014</span> per decade, comparable to observed global rates of OA. However, bottom water pH decreases at twice the rate of surface pH, while bottom [H<span class="inline-formula"><sup>+</sup></span>] decreases at nearly 3 times the rate of surface [H<span class="inline-formula"><sup>+</sup></span>]. This amplified bottom water acidification has emerged over the past 25 years and is likely driven by a combination of anthropogenic carbon accumulation and increasing primary productivity and subsurface respiration and remineralization. Due to this enhanced bottom water acidification, the spatial extent of bottom waters with <span class="inline-formula">Ω<sub>arag</sub><1</span> has greatly expanded over the past 2 decades, along with pH conditions harmful to red king crab. Interannual variability in surface and bottom <span class="inline-formula">Ω<sub>arag</sub></span>, pH, and [H<span class="inline-formula"><sup>+</sup></span>] has also increased over the past 2 decades, resulting in part from the increased physical climate variability. We also find that the Bering Sea shelf is a net annual carbon sink of 1.1–7.9 Tg C yr<span class="inline-formula"><sup>−1</sup></span>, with the range resulting from the difference in the two different atmospheric forcing reanalysis products used. Seasonally, the shelf is a significant carbon sink from April–October but a somewhat weaker carbon source from November–March.</p> |
| format | Article |
| id | doaj-art-d36b677956c64253ba207b14710fe3fc |
| institution | OA Journals |
| issn | 1726-4170 1726-4189 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj-art-d36b677956c64253ba207b14710fe3fc2025-08-20T02:38:42ZengCopernicus PublicationsBiogeosciences1726-41701726-41892025-07-01223103312510.5194/bg-22-3103-2025Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022D. J. Pilcher0D. J. Pilcher1J. N. Cross2J. N. Cross3N. Monacci4L. Mu5K. A. Kearney6K. A. Kearney7A. J. Hermann8A. J. Hermann9W. Cheng10W. Cheng11Cooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA, USANOAA Pacific Marine Environmental Laboratory, Seattle, WA, USANOAA Pacific Marine Environmental Laboratory, Seattle, WA, USAPacific Northwest National Laboratory, Sequim, WA, USACollege of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, 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, USANOAA Alaska Fisheries Science Center, Seattle, WA, USACooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA, USANOAA Pacific Marine Environmental Laboratory, Seattle, WA, USACooperative Institute for Climate, Ocean, and Ecosystem Studies, University of Washington, Seattle, WA, USANOAA Pacific Marine Environmental Laboratory, Seattle, WA, USA<p>The Bering Sea shelf supports a highly productive marine ecosystem that is vulnerable to ocean acidification (OA) due to the cold, carbon-rich waters. Previous observational evidence suggests that bottom waters on the shelf are already seasonally undersaturated with respect to aragonite (i.e. <span class="inline-formula">Ω<sub>arag</sub><1</span>) and that OA will continue to increase the spatial extent, duration, and intensity of these conditions. Here, we use a regional ocean biogeochemical model to simulate changes in ocean carbon chemistry for the Bering Sea shelf from 1970–2022. Over this timeframe, model results suggest that surface <span class="inline-formula">Ω<sub>arag</sub></span> decreases by <span class="inline-formula">−0.043</span> per decade and surface pH by <span class="inline-formula">−0.014</span> per decade, comparable to observed global rates of OA. However, bottom water pH decreases at twice the rate of surface pH, while bottom [H<span class="inline-formula"><sup>+</sup></span>] decreases at nearly 3 times the rate of surface [H<span class="inline-formula"><sup>+</sup></span>]. This amplified bottom water acidification has emerged over the past 25 years and is likely driven by a combination of anthropogenic carbon accumulation and increasing primary productivity and subsurface respiration and remineralization. Due to this enhanced bottom water acidification, the spatial extent of bottom waters with <span class="inline-formula">Ω<sub>arag</sub><1</span> has greatly expanded over the past 2 decades, along with pH conditions harmful to red king crab. Interannual variability in surface and bottom <span class="inline-formula">Ω<sub>arag</sub></span>, pH, and [H<span class="inline-formula"><sup>+</sup></span>] has also increased over the past 2 decades, resulting in part from the increased physical climate variability. We also find that the Bering Sea shelf is a net annual carbon sink of 1.1–7.9 Tg C yr<span class="inline-formula"><sup>−1</sup></span>, with the range resulting from the difference in the two different atmospheric forcing reanalysis products used. Seasonally, the shelf is a significant carbon sink from April–October but a somewhat weaker carbon source from November–March.</p>https://bg.copernicus.org/articles/22/3103/2025/bg-22-3103-2025.pdf |
| spellingShingle | D. J. Pilcher D. J. Pilcher J. N. Cross J. N. Cross N. Monacci L. Mu K. A. Kearney K. A. Kearney A. J. Hermann A. J. Hermann W. Cheng W. Cheng Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022 Biogeosciences |
| title | Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022 |
| title_full | Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022 |
| title_fullStr | Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022 |
| title_full_unstemmed | Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022 |
| title_short | Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022 |
| title_sort | amplified bottom water acidification rates on the bering sea shelf from 1970 2022 |
| url | https://bg.copernicus.org/articles/22/3103/2025/bg-22-3103-2025.pdf |
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