Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble
The uptake of anthropogenic carbon (Cant) by the ocean leads to ocean acidification, causing the reduction of pH and the saturation states of aragonite (Ωarag) and calcite (Ωcalc). The Arctic Ocean is particularly vulnerable to ocean acidification due to its naturally low pH and saturation states an...
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ftnorce:oai:norceresearch.brage.unit.no:11250/3133144 2024-06-23T07:49:08+00:00 Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble Terhaar, Jens Torres, Olivier Bourgeois, Timothée Kwiatkowski, Lester 2021 application/pdf https://hdl.handle.net/11250/3133144 https://doi.org/10.5194/bg-18-2221-2021 eng eng EC/H2020/641816 Norges forskningsråd: 275268 EC/H2020/820989 EC/H2020/821003 urn:issn:1726-4170 https://hdl.handle.net/11250/3133144 https://doi.org/10.5194/bg-18-2221-2021 cristin:1902537 Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no © Author(s) 2021 Biogeosciences Journal article Peer reviewed 2021 ftnorce https://doi.org/10.5194/bg-18-2221-2021 2024-06-09T23:34:16Z The uptake of anthropogenic carbon (Cant) by the ocean leads to ocean acidification, causing the reduction of pH and the saturation states of aragonite (Ωarag) and calcite (Ωcalc). The Arctic Ocean is particularly vulnerable to ocean acidification due to its naturally low pH and saturation states and due to ongoing freshening and the concurrent reduction in total alkalinity in this region. Here, we analyse ocean acidification in the Arctic Ocean over the 21st century across 14 Earth system models (ESMs) from the latest Coupled Model Intercomparison Project Phase 6 (CMIP6). Compared to the previous model generation (CMIP5), models generally better simulate maximum sea surface densities in the Arctic Ocean and consequently the transport of Cant into the Arctic Ocean interior, with simulated historical increases in Cant in improved agreement with observational products. Moreover, in CMIP6 the inter-model uncertainty of projected changes over the 21st century in Arctic Ocean Ωarag and Ωcalc averaged over the upper 1000 m is reduced by 44–64 %. The strong reduction in projection uncertainties of Ωarag and Ωcalc can be attributed to compensation between Cant uptake and total alkalinity reduction in the latest models. Specifically, ESMs with a large increase in Arctic Ocean Cant over the 21st century tend to simulate a relatively weak concurrent freshening and alkalinity reduction, while ESMs with a small increase in Cant simulate a relatively strong freshening and concurrent total alkalinity reduction. Although both mechanisms contribute to Arctic Ocean acidification over the 21st century, the increase in Cant remains the dominant driver. Even under the low-emissions Shared Socioeconomic Pathway 1-2.6 (SSP1-2.6), basin-wide averaged Ωarag undersaturation in the upper 1000 m occurs before the end of the century. While under the high-emissions pathway SSP5-8.5, the Arctic Ocean mesopelagic is projected to even become undersaturated with respect to calcite. An emergent constraint identified in CMIP5 which relates ... Article in Journal/Newspaper Arctic Arctic Ocean Arctic Ocean Acidification Ocean acidification NORCE vitenarkiv (Norwegian Research Centre) Arctic Arctic Ocean Biogeosciences 18 6 2221 2240 |
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Open Polar |
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NORCE vitenarkiv (Norwegian Research Centre) |
op_collection_id |
ftnorce |
language |
English |
description |
The uptake of anthropogenic carbon (Cant) by the ocean leads to ocean acidification, causing the reduction of pH and the saturation states of aragonite (Ωarag) and calcite (Ωcalc). The Arctic Ocean is particularly vulnerable to ocean acidification due to its naturally low pH and saturation states and due to ongoing freshening and the concurrent reduction in total alkalinity in this region. Here, we analyse ocean acidification in the Arctic Ocean over the 21st century across 14 Earth system models (ESMs) from the latest Coupled Model Intercomparison Project Phase 6 (CMIP6). Compared to the previous model generation (CMIP5), models generally better simulate maximum sea surface densities in the Arctic Ocean and consequently the transport of Cant into the Arctic Ocean interior, with simulated historical increases in Cant in improved agreement with observational products. Moreover, in CMIP6 the inter-model uncertainty of projected changes over the 21st century in Arctic Ocean Ωarag and Ωcalc averaged over the upper 1000 m is reduced by 44–64 %. The strong reduction in projection uncertainties of Ωarag and Ωcalc can be attributed to compensation between Cant uptake and total alkalinity reduction in the latest models. Specifically, ESMs with a large increase in Arctic Ocean Cant over the 21st century tend to simulate a relatively weak concurrent freshening and alkalinity reduction, while ESMs with a small increase in Cant simulate a relatively strong freshening and concurrent total alkalinity reduction. Although both mechanisms contribute to Arctic Ocean acidification over the 21st century, the increase in Cant remains the dominant driver. Even under the low-emissions Shared Socioeconomic Pathway 1-2.6 (SSP1-2.6), basin-wide averaged Ωarag undersaturation in the upper 1000 m occurs before the end of the century. While under the high-emissions pathway SSP5-8.5, the Arctic Ocean mesopelagic is projected to even become undersaturated with respect to calcite. An emergent constraint identified in CMIP5 which relates ... |
format |
Article in Journal/Newspaper |
author |
Terhaar, Jens Torres, Olivier Bourgeois, Timothée Kwiatkowski, Lester |
spellingShingle |
Terhaar, Jens Torres, Olivier Bourgeois, Timothée Kwiatkowski, Lester Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble |
author_facet |
Terhaar, Jens Torres, Olivier Bourgeois, Timothée Kwiatkowski, Lester |
author_sort |
Terhaar, Jens |
title |
Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble |
title_short |
Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble |
title_full |
Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble |
title_fullStr |
Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble |
title_full_unstemmed |
Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble |
title_sort |
arctic ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the cmip6 model ensemble |
publishDate |
2021 |
url |
https://hdl.handle.net/11250/3133144 https://doi.org/10.5194/bg-18-2221-2021 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean Arctic Ocean Acidification Ocean acidification |
genre_facet |
Arctic Arctic Ocean Arctic Ocean Acidification Ocean acidification |
op_source |
Biogeosciences |
op_relation |
EC/H2020/641816 Norges forskningsråd: 275268 EC/H2020/820989 EC/H2020/821003 urn:issn:1726-4170 https://hdl.handle.net/11250/3133144 https://doi.org/10.5194/bg-18-2221-2021 cristin:1902537 |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no © Author(s) 2021 |
op_doi |
https://doi.org/10.5194/bg-18-2221-2021 |
container_title |
Biogeosciences |
container_volume |
18 |
container_issue |
6 |
container_start_page |
2221 |
op_container_end_page |
2240 |
_version_ |
1802639401906339840 |