Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p CO 2 and seawater composition over the last 130 000 years: a model study
We have developed and employed an Earth system model to explore the forcings of atmospheric p CO 2 change and the chemical and isotopic evolution of seawater over the last glacial cycle. Concentrations of dissolved phosphorus (DP), reactive nitrogen, molecular oxygen, dissolved inorganic carbon (DIC...
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Copernicus Publications
2016
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Online Access: | https://doi.org/10.5194/cp-12-339-2016 https://doaj.org/article/e2e1d7c878cd4990b5f5a4e2da34b2ff |
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ftdoajarticles:oai:doaj.org/article:e2e1d7c878cd4990b5f5a4e2da34b2ff 2023-05-15T18:24:54+02:00 Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p CO 2 and seawater composition over the last 130 000 years: a model study K. Wallmann B. Schneider M. Sarnthein 2016-02-01T00:00:00Z https://doi.org/10.5194/cp-12-339-2016 https://doaj.org/article/e2e1d7c878cd4990b5f5a4e2da34b2ff EN eng Copernicus Publications http://www.clim-past.net/12/339/2016/cp-12-339-2016.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 doi:10.5194/cp-12-339-2016 https://doaj.org/article/e2e1d7c878cd4990b5f5a4e2da34b2ff Climate of the Past, Vol 12, Iss 2, Pp 339-375 (2016) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2016 ftdoajarticles https://doi.org/10.5194/cp-12-339-2016 2022-12-31T13:46:24Z We have developed and employed an Earth system model to explore the forcings of atmospheric p CO 2 change and the chemical and isotopic evolution of seawater over the last glacial cycle. Concentrations of dissolved phosphorus (DP), reactive nitrogen, molecular oxygen, dissolved inorganic carbon (DIC), total alkalinity (TA), 13 C-DIC, and 14 C-DIC were calculated for 24 ocean boxes. The bi-directional water fluxes between these model boxes were derived from a 3-D circulation field of the modern ocean (Opa 8.2, NEMO) and tuned such that tracer distributions calculated by the box model were consistent with observational data from the modern ocean. To model the last 130 kyr, we employed records of past changes in sea-level, ocean circulation, and dust deposition. According to the model, about half of the glacial p CO 2 drawdown may be attributed to marine regressions. The glacial sea-level low-stands implied steepened ocean margins, a reduced burial of particulate organic carbon, phosphorus, and neritic carbonate at the margin seafloor, a decline in benthic denitrification, and enhanced weathering of emerged shelf sediments. In turn, low-stands led to a distinct rise in the standing stocks of DIC, TA, and nutrients in the global ocean, promoted the glacial sequestration of atmospheric CO 2 in the ocean, and added 13 C- and 14 C-depleted DIC to the ocean as recorded in benthic foraminifera signals. The other half of the glacial drop in p CO 2 was linked to inferred shoaling of Atlantic meridional overturning circulation and more efficient utilization of nutrients in the Southern Ocean. The diminished ventilation of deep water in the glacial Atlantic and Southern Ocean led to significant 14 C depletions with respect to the atmosphere. According to our model, the deglacial rapid and stepwise rise in atmospheric p CO 2 was induced by upwelling both in the Southern Ocean and subarctic North Pacific and promoted by a drop in nutrient utilization in the Southern Ocean. The deglacial sea-level rise led to a gradual decline ... Article in Journal/Newspaper Southern Ocean Subarctic Directory of Open Access Journals: DOAJ Articles Pacific Southern Ocean Climate of the Past 12 2 339 375 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
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ftdoajarticles |
language |
English |
topic |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
spellingShingle |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 K. Wallmann B. Schneider M. Sarnthein Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p CO 2 and seawater composition over the last 130 000 years: a model study |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
We have developed and employed an Earth system model to explore the forcings of atmospheric p CO 2 change and the chemical and isotopic evolution of seawater over the last glacial cycle. Concentrations of dissolved phosphorus (DP), reactive nitrogen, molecular oxygen, dissolved inorganic carbon (DIC), total alkalinity (TA), 13 C-DIC, and 14 C-DIC were calculated for 24 ocean boxes. The bi-directional water fluxes between these model boxes were derived from a 3-D circulation field of the modern ocean (Opa 8.2, NEMO) and tuned such that tracer distributions calculated by the box model were consistent with observational data from the modern ocean. To model the last 130 kyr, we employed records of past changes in sea-level, ocean circulation, and dust deposition. According to the model, about half of the glacial p CO 2 drawdown may be attributed to marine regressions. The glacial sea-level low-stands implied steepened ocean margins, a reduced burial of particulate organic carbon, phosphorus, and neritic carbonate at the margin seafloor, a decline in benthic denitrification, and enhanced weathering of emerged shelf sediments. In turn, low-stands led to a distinct rise in the standing stocks of DIC, TA, and nutrients in the global ocean, promoted the glacial sequestration of atmospheric CO 2 in the ocean, and added 13 C- and 14 C-depleted DIC to the ocean as recorded in benthic foraminifera signals. The other half of the glacial drop in p CO 2 was linked to inferred shoaling of Atlantic meridional overturning circulation and more efficient utilization of nutrients in the Southern Ocean. The diminished ventilation of deep water in the glacial Atlantic and Southern Ocean led to significant 14 C depletions with respect to the atmosphere. According to our model, the deglacial rapid and stepwise rise in atmospheric p CO 2 was induced by upwelling both in the Southern Ocean and subarctic North Pacific and promoted by a drop in nutrient utilization in the Southern Ocean. The deglacial sea-level rise led to a gradual decline ... |
format |
Article in Journal/Newspaper |
author |
K. Wallmann B. Schneider M. Sarnthein |
author_facet |
K. Wallmann B. Schneider M. Sarnthein |
author_sort |
K. Wallmann |
title |
Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p CO 2 and seawater composition over the last 130 000 years: a model study |
title_short |
Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p CO 2 and seawater composition over the last 130 000 years: a model study |
title_full |
Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p CO 2 and seawater composition over the last 130 000 years: a model study |
title_fullStr |
Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p CO 2 and seawater composition over the last 130 000 years: a model study |
title_full_unstemmed |
Effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p CO 2 and seawater composition over the last 130 000 years: a model study |
title_sort |
effects of eustatic sea-level change, ocean dynamics, and nutrient utilization on atmospheric p co 2 and seawater composition over the last 130 000 years: a model study |
publisher |
Copernicus Publications |
publishDate |
2016 |
url |
https://doi.org/10.5194/cp-12-339-2016 https://doaj.org/article/e2e1d7c878cd4990b5f5a4e2da34b2ff |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
Southern Ocean Subarctic |
genre_facet |
Southern Ocean Subarctic |
op_source |
Climate of the Past, Vol 12, Iss 2, Pp 339-375 (2016) |
op_relation |
http://www.clim-past.net/12/339/2016/cp-12-339-2016.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 doi:10.5194/cp-12-339-2016 https://doaj.org/article/e2e1d7c878cd4990b5f5a4e2da34b2ff |
op_doi |
https://doi.org/10.5194/cp-12-339-2016 |
container_title |
Climate of the Past |
container_volume |
12 |
container_issue |
2 |
container_start_page |
339 |
op_container_end_page |
375 |
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1766205929209987072 |