Evaluating the biological pump efficiency of the Last Glacial Maximum ocean using δ13C
Although both physical and biological marine changes are required to explain the 100 ppm lower atmospheric pCO2 of the Last Glacial Maximum (LGM, ∼21 ka) as compared to preindustrial (PI) times, their exact contributions are debated. Proxies of past marine carbon cycling (such as δ13C) document thes...
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ftunivbergen:oai:bora.uib.no:11250/2766977 2023-05-15T18:18:54+02:00 Evaluating the biological pump efficiency of the Last Glacial Maximum ocean using δ13C Morée, Anne Schwinger, Jörg Ninnemann, Ulysses S Jeltsch-Thommes, Aurich Bethke, Ingo Heinze, Christoph 2021 application/pdf https://hdl.handle.net/11250/2766977 https://doi.org/10.5194/cp-17-753-2021 eng eng Copernicus Publications Norges forskningsråd: 270061 Notur/NorStore: NN2980K Norges forskningsråd: 229771 Notur/NorStore: NN2345K EC/H2020/641816 Notur/NorStore: NS2980K Notur/NorStore: NS2345K urn:issn:1814-9324 https://hdl.handle.net/11250/2766977 https://doi.org/10.5194/cp-17-753-2021 cristin:1902792 Climate of the Past. 2021, 17, 753-774. Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright Author(s) 2021. Climate of the Past 753-774 17 Journal article Peer reviewed 2021 ftunivbergen https://doi.org/10.5194/cp-17-753-2021 2023-03-14T17:39:07Z Although both physical and biological marine changes are required to explain the 100 ppm lower atmospheric pCO2 of the Last Glacial Maximum (LGM, ∼21 ka) as compared to preindustrial (PI) times, their exact contributions are debated. Proxies of past marine carbon cycling (such as δ13C) document these changes and thus provide constraints for quantifying the drivers of long-term carbon cycle variability. This modeling study discusses the physical and biological changes in the ocean needed to simulate an LGM ocean in satisfactory agreement with proxy data, here focusing especially on δ13C. We prepared a PI and LGM equilibrium simulation using the ocean model NorESM-OC with full biogeochemistry (including the carbon isotopes δ13C and radiocarbon) and dynamic sea ice. The modeled LGM–PI differences are evaluated against a wide range of physical and biogeochemical proxy data and show agreement for key aspects of the physical ocean state within the data uncertainties. However, the lack of a simulated increase of regenerated nutrients for the LGM indicates that additional biogeochemical changes are required to simulate an LGM ocean in agreement with proxy data. In order to examine these changes, we explore the potential effects of different global mean biological pump efficiencies on the simulated marine biogeochemical tracer distributions. Through estimating which biological pump efficiency reduces LGM model–proxy biases the most, we estimate that the global mean biological pump efficiency increased from 38 % (PI) to up to 75 % (LGM). The drivers of such an increase in the biological pump efficiency may be both biological and related to circulation changes that are incompletely captured by our model – such as stronger isolation of Southern Source Water. Finally, even after considering a 75 % biological pump efficiency in the LGM ocean, a remaining model–proxy error in δ13C exists that is 0.07 ‰ larger than the 0.19 ‰ data uncertainty. This error indicates that additional changes in ocean dynamics are needed to simulate ... Article in Journal/Newspaper Sea ice University of Bergen: Bergen Open Research Archive (BORA-UiB) Climate of the Past 17 2 753 774 |
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Open Polar |
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University of Bergen: Bergen Open Research Archive (BORA-UiB) |
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ftunivbergen |
language |
English |
description |
Although both physical and biological marine changes are required to explain the 100 ppm lower atmospheric pCO2 of the Last Glacial Maximum (LGM, ∼21 ka) as compared to preindustrial (PI) times, their exact contributions are debated. Proxies of past marine carbon cycling (such as δ13C) document these changes and thus provide constraints for quantifying the drivers of long-term carbon cycle variability. This modeling study discusses the physical and biological changes in the ocean needed to simulate an LGM ocean in satisfactory agreement with proxy data, here focusing especially on δ13C. We prepared a PI and LGM equilibrium simulation using the ocean model NorESM-OC with full biogeochemistry (including the carbon isotopes δ13C and radiocarbon) and dynamic sea ice. The modeled LGM–PI differences are evaluated against a wide range of physical and biogeochemical proxy data and show agreement for key aspects of the physical ocean state within the data uncertainties. However, the lack of a simulated increase of regenerated nutrients for the LGM indicates that additional biogeochemical changes are required to simulate an LGM ocean in agreement with proxy data. In order to examine these changes, we explore the potential effects of different global mean biological pump efficiencies on the simulated marine biogeochemical tracer distributions. Through estimating which biological pump efficiency reduces LGM model–proxy biases the most, we estimate that the global mean biological pump efficiency increased from 38 % (PI) to up to 75 % (LGM). The drivers of such an increase in the biological pump efficiency may be both biological and related to circulation changes that are incompletely captured by our model – such as stronger isolation of Southern Source Water. Finally, even after considering a 75 % biological pump efficiency in the LGM ocean, a remaining model–proxy error in δ13C exists that is 0.07 ‰ larger than the 0.19 ‰ data uncertainty. This error indicates that additional changes in ocean dynamics are needed to simulate ... |
format |
Article in Journal/Newspaper |
author |
Morée, Anne Schwinger, Jörg Ninnemann, Ulysses S Jeltsch-Thommes, Aurich Bethke, Ingo Heinze, Christoph |
spellingShingle |
Morée, Anne Schwinger, Jörg Ninnemann, Ulysses S Jeltsch-Thommes, Aurich Bethke, Ingo Heinze, Christoph Evaluating the biological pump efficiency of the Last Glacial Maximum ocean using δ13C |
author_facet |
Morée, Anne Schwinger, Jörg Ninnemann, Ulysses S Jeltsch-Thommes, Aurich Bethke, Ingo Heinze, Christoph |
author_sort |
Morée, Anne |
title |
Evaluating the biological pump efficiency of the Last Glacial Maximum ocean using δ13C |
title_short |
Evaluating the biological pump efficiency of the Last Glacial Maximum ocean using δ13C |
title_full |
Evaluating the biological pump efficiency of the Last Glacial Maximum ocean using δ13C |
title_fullStr |
Evaluating the biological pump efficiency of the Last Glacial Maximum ocean using δ13C |
title_full_unstemmed |
Evaluating the biological pump efficiency of the Last Glacial Maximum ocean using δ13C |
title_sort |
evaluating the biological pump efficiency of the last glacial maximum ocean using δ13c |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://hdl.handle.net/11250/2766977 https://doi.org/10.5194/cp-17-753-2021 |
genre |
Sea ice |
genre_facet |
Sea ice |
op_source |
Climate of the Past 753-774 17 |
op_relation |
Norges forskningsråd: 270061 Notur/NorStore: NN2980K Norges forskningsråd: 229771 Notur/NorStore: NN2345K EC/H2020/641816 Notur/NorStore: NS2980K Notur/NorStore: NS2345K urn:issn:1814-9324 https://hdl.handle.net/11250/2766977 https://doi.org/10.5194/cp-17-753-2021 cristin:1902792 Climate of the Past. 2021, 17, 753-774. |
op_rights |
Navngivelse 4.0 Internasjonal http://creativecommons.org/licenses/by/4.0/deed.no Copyright Author(s) 2021. |
op_doi |
https://doi.org/10.5194/cp-17-753-2021 |
container_title |
Climate of the Past |
container_volume |
17 |
container_issue |
2 |
container_start_page |
753 |
op_container_end_page |
774 |
_version_ |
1766195654355320832 |