Ocean acidification trends and carbonate system dynamics across the North Atlantic subpolar gyre water masses during 2009–2019
<p>The CO<span class="inline-formula"><sub>2</sub></span>–carbonate system dynamics in the North Atlantic subpolar gyre (NASPG) were evaluated between 2009 and 2019. Data were collected aboard eight summer cruises through the Climate and Ocean: Variability, Pr...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2024-12-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/21/5561/2024/bg-21-5561-2024.pdf |
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| Summary: | <p>The CO<span class="inline-formula"><sub>2</sub></span>–carbonate system dynamics in the North Atlantic subpolar gyre (NASPG) were evaluated between 2009 and 2019. Data were collected aboard eight summer cruises through the Climate and Ocean: Variability, Predictability and Change (CLIVAR) 59.5° N section. The ocean acidification (OA) patterns and the reduction in the saturation state of calcite (<span class="inline-formula">Ω<sub>Ca</sub></span>) and aragonite (<span class="inline-formula">Ω<sub>Arag</sub></span>) in response to the increasing anthropogenic CO<span class="inline-formula"><sub>2</sub></span> (<span class="inline-formula"><i>C</i><sub>ant</sub></span>) were assessed within the Irminger, Iceland, and Rockall basins during a poorly assessed decade in which the physical patterns reversed in comparison with previous well-known periods. The observed cooling, freshening, and enhanced ventilation increased the interannual rate of accumulation of <span class="inline-formula"><i>C</i><sub>ant</sub></span> in the interior ocean by 50 %–86 % and the OA rates by close to 10 %. The OA trends were 0.0013–0.0032 units yr<span class="inline-formula"><sup>−1</sup></span> in the Irminger and Iceland basins and 0.0006–0.0024 units yr<span class="inline-formula"><sup>−1</sup></span> in the Rockall Trough, causing a decline in <span class="inline-formula">Ω<sub>Ca</sub></span> and <span class="inline-formula">Ω<sub>Arag</sub></span> of 0.004–0.021 and 0.003–0.0013 units yr<span class="inline-formula"><sup>−1</sup></span>, respectively. The <span class="inline-formula"><i>C</i><sub>ant</sub></span>-driven rise in total inorganic carbon (<span class="inline-formula"><i>C</i><sub>T</sub></span>) was the main driver of the OA (contributed by 53 %–68 % in upper layers and <span class="inline-formula"><i>></i></span> 82 % toward the interior ocean) and the reduction in <span class="inline-formula">Ω<sub>Ca</sub></span> and <span class="inline-formula">Ω<sub>Arag</sub></span> (<span class="inline-formula"><i>></i></span> 64 %). The transient decrease in temperature, salinity, and <span class="inline-formula"><i>A</i><sub>T</sub></span> collectively counteracts the <span class="inline-formula"><i>C</i><sub>T</sub></span>-driven acidification by 45 %–85 % in the upper layers and in the shallow Rockall Trough and by <span class="inline-formula"><i><</i></span> 10 % in the interior ocean. The present investigation reports the acceleration of the OA within the NASPG and expands knowledge about the future state of the ocean.</p> |
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| ISSN: | 1726-4170 1726-4189 |