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 ( C ant ) by the ocean leads to ocean acidification, causing the reduction of pH and the saturation states of aragonite ( Ω arag ) and calcite ( Ω calc ). The Arctic Ocean is particularly vulnerable to ocean acidification due to its naturally low pH and saturation...
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2021
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ftdoajarticles:oai:doaj.org/article:dd5fa057cdc14d2a82dab4814b5e145e 2023-05-15T14:36:50+02:00 Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble J. Terhaar O. Torres T. Bourgeois L. Kwiatkowski 2021-04-01T00:00:00Z https://doi.org/10.5194/bg-18-2221-2021 https://doaj.org/article/dd5fa057cdc14d2a82dab4814b5e145e EN eng Copernicus Publications https://bg.copernicus.org/articles/18/2221/2021/bg-18-2221-2021.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-18-2221-2021 1726-4170 1726-4189 https://doaj.org/article/dd5fa057cdc14d2a82dab4814b5e145e Biogeosciences, Vol 18, Pp 2221-2240 (2021) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/bg-18-2221-2021 2022-12-31T06:55:25Z The uptake of anthropogenic carbon ( C ant ) by the ocean leads to ocean acidification, causing the reduction of pH and the saturation states of aragonite ( Ω arag ) and calcite ( Ω calc ). 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 C ant into the Arctic Ocean interior, with simulated historical increases in C ant in improved agreement with observational products. Moreover, in CMIP6 the inter-model uncertainty of projected changes over the 21st century in Arctic Ocean Ω arag and Ω calc averaged over the upper 1000 m is reduced by 44–64 %. The strong reduction in projection uncertainties of Ω arag and Ω calc can be attributed to compensation between C ant uptake and total alkalinity reduction in the latest models. Specifically, ESMs with a large increase in Arctic Ocean C ant over the 21st century tend to simulate a relatively weak concurrent freshening and alkalinity reduction, while ESMs with a small increase in C ant 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 C ant remains the dominant driver. Even under the low-emissions Shared Socioeconomic Pathway 1-2.6 (SSP1-2.6), basin-wide averaged Ω arag 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 ... Article in Journal/Newspaper Arctic Arctic Ocean Arctic Ocean Acidification Ocean acidification Directory of Open Access Journals: DOAJ Articles Arctic Arctic Ocean Biogeosciences 18 6 2221 2240 |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 J. Terhaar O. Torres T. Bourgeois L. Kwiatkowski Arctic Ocean acidification over the 21st century co-driven by anthropogenic carbon increases and freshening in the CMIP6 model ensemble |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
The uptake of anthropogenic carbon ( C ant ) by the ocean leads to ocean acidification, causing the reduction of pH and the saturation states of aragonite ( Ω arag ) and calcite ( Ω calc ). 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 C ant into the Arctic Ocean interior, with simulated historical increases in C ant in improved agreement with observational products. Moreover, in CMIP6 the inter-model uncertainty of projected changes over the 21st century in Arctic Ocean Ω arag and Ω calc averaged over the upper 1000 m is reduced by 44–64 %. The strong reduction in projection uncertainties of Ω arag and Ω calc can be attributed to compensation between C ant uptake and total alkalinity reduction in the latest models. Specifically, ESMs with a large increase in Arctic Ocean C ant over the 21st century tend to simulate a relatively weak concurrent freshening and alkalinity reduction, while ESMs with a small increase in C ant 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 C ant remains the dominant driver. Even under the low-emissions Shared Socioeconomic Pathway 1-2.6 (SSP1-2.6), basin-wide averaged Ω arag 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 ... |
format |
Article in Journal/Newspaper |
author |
J. Terhaar O. Torres T. Bourgeois L. Kwiatkowski |
author_facet |
J. Terhaar O. Torres T. Bourgeois L. Kwiatkowski |
author_sort |
J. Terhaar |
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 |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/bg-18-2221-2021 https://doaj.org/article/dd5fa057cdc14d2a82dab4814b5e145e |
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, Vol 18, Pp 2221-2240 (2021) |
op_relation |
https://bg.copernicus.org/articles/18/2221/2021/bg-18-2221-2021.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 doi:10.5194/bg-18-2221-2021 1726-4170 1726-4189 https://doaj.org/article/dd5fa057cdc14d2a82dab4814b5e145e |
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 |
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1766309367307567104 |