A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years
The circulation of intermediate waters plays an important role in global heat and carbon transport in the ocean and changes in their distribution are closely tied to glacial–interglacial climate change. Coupled radiocarbon and U/Th measurements on deep-sea Desmophyllum dianthus corals allow for the...
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ftcaltechauth:oai:authors.library.caltech.edu:61966 2023-05-15T13:57:16+02:00 A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years Hines, Sophia K. V. Southon, John R. Adkins, Jess F. 2015-12-15 application/pdf https://authors.library.caltech.edu/61966/ https://authors.library.caltech.edu/61966/2/mmc4.pdf https://authors.library.caltech.edu/61966/3/mmc5.pdf https://resolver.caltech.edu/CaltechAUTHORS:20151106-150028884 en eng Elsevier https://authors.library.caltech.edu/61966/2/mmc4.pdf https://authors.library.caltech.edu/61966/3/mmc5.pdf Hines, Sophia K. V. and Southon, John R. and Adkins, Jess F. (2015) A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years. Earth and Planetary Science Letters, 432 . pp. 46-58. ISSN 0012-821X. doi:10.1016/j.epsl.2015.09.038. https://resolver.caltech.edu/CaltechAUTHORS:20151106-150028884 <https://resolver.caltech.edu/CaltechAUTHORS:20151106-150028884> other Article PeerReviewed 2015 ftcaltechauth https://doi.org/10.1016/j.epsl.2015.09.038 2021-11-11T19:06:46Z The circulation of intermediate waters plays an important role in global heat and carbon transport in the ocean and changes in their distribution are closely tied to glacial–interglacial climate change. Coupled radiocarbon and U/Th measurements on deep-sea Desmophyllum dianthus corals allow for the reconstruction of past intermediate water ventilation. We present a high-resolution time series of Antarctic Intermediate Water radiocarbon from 44 corals spanning 30 ka through the start of the Holocene, encompassing the transition into the Last Glacial Maximum (LGM) and the last deglaciation. Corals were collected south of Tasmania from water depths between 1430 and 1950 m with 80% of them between 1500 and 1700 m, giving us a continuous record from a narrow depth range. The record shows three distinct periods of circulation: the MIS 3–2 transition, the LGM/Heinrich Stadial 1 (extending from ∼22 to 16 kyr BP), and the Antarctic Cold Reversal (ACR). The MIS 3–2 transition and the ACR are characterized by abrupt changes in intermediate water radiocarbon while the LGM time period generally follows the atmosphere at a constant offset, in support of the idea that the LGM ocean was at steady state for its ^(14)C distribution. Closer inspection of the LGM time period reveals a 40‰ jump at ∼19 ka from an atmospheric offset of roughly 230‰ to 190‰, coincident with an observed 10–15 m rise in sea level and a southward shift of the Subantarctic and Polar Fronts, an abrupt change not seen in deeper records. During the ACR time period intermediate water radiocarbon is on average less offset from the atmosphere (∼110‰∼110‰) and much more variable. This variability has been captured within the lifetimes of three individual corals with changes of up to 35‰ over ∼40 yr, likely caused by the movement of Southern Ocean fronts. This surprising result of relatively young and variable intermediate water radiocarbon during the ACR seems to go against the canonical idea of reduced circulation and ventilation in the south during this time period. However comparisons with other records from the Southern Ocean highlight zonal asymmetries, which can explain the deviation of our Tasmanian record from those in Drake Passage and the eastern Pacific. These signals seen in Tasmanian intermediate water Δ^(14)C can also be found in Greenland ice core δ^(18)O and East Asian monsoon strength. Throughout the LGM and the deglaciation, our Tasmanian intermediate water record is sensitive to times when the upper and lower cells of the meridional overturning circulation are more or less interconnected, which has important implications for the global climate system on glacial–interglacial time scales. Article in Journal/Newspaper Antarc* Antarctic Drake Passage Greenland Greenland ice core ice core Southern Ocean Caltech Authors (California Institute of Technology) Antarctic Drake Passage Greenland Pacific Southern Ocean The Antarctic Earth and Planetary Science Letters 432 46 58 |
institution |
Open Polar |
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Caltech Authors (California Institute of Technology) |
op_collection_id |
ftcaltechauth |
language |
English |
description |
The circulation of intermediate waters plays an important role in global heat and carbon transport in the ocean and changes in their distribution are closely tied to glacial–interglacial climate change. Coupled radiocarbon and U/Th measurements on deep-sea Desmophyllum dianthus corals allow for the reconstruction of past intermediate water ventilation. We present a high-resolution time series of Antarctic Intermediate Water radiocarbon from 44 corals spanning 30 ka through the start of the Holocene, encompassing the transition into the Last Glacial Maximum (LGM) and the last deglaciation. Corals were collected south of Tasmania from water depths between 1430 and 1950 m with 80% of them between 1500 and 1700 m, giving us a continuous record from a narrow depth range. The record shows three distinct periods of circulation: the MIS 3–2 transition, the LGM/Heinrich Stadial 1 (extending from ∼22 to 16 kyr BP), and the Antarctic Cold Reversal (ACR). The MIS 3–2 transition and the ACR are characterized by abrupt changes in intermediate water radiocarbon while the LGM time period generally follows the atmosphere at a constant offset, in support of the idea that the LGM ocean was at steady state for its ^(14)C distribution. Closer inspection of the LGM time period reveals a 40‰ jump at ∼19 ka from an atmospheric offset of roughly 230‰ to 190‰, coincident with an observed 10–15 m rise in sea level and a southward shift of the Subantarctic and Polar Fronts, an abrupt change not seen in deeper records. During the ACR time period intermediate water radiocarbon is on average less offset from the atmosphere (∼110‰∼110‰) and much more variable. This variability has been captured within the lifetimes of three individual corals with changes of up to 35‰ over ∼40 yr, likely caused by the movement of Southern Ocean fronts. This surprising result of relatively young and variable intermediate water radiocarbon during the ACR seems to go against the canonical idea of reduced circulation and ventilation in the south during this time period. However comparisons with other records from the Southern Ocean highlight zonal asymmetries, which can explain the deviation of our Tasmanian record from those in Drake Passage and the eastern Pacific. These signals seen in Tasmanian intermediate water Δ^(14)C can also be found in Greenland ice core δ^(18)O and East Asian monsoon strength. Throughout the LGM and the deglaciation, our Tasmanian intermediate water record is sensitive to times when the upper and lower cells of the meridional overturning circulation are more or less interconnected, which has important implications for the global climate system on glacial–interglacial time scales. |
format |
Article in Journal/Newspaper |
author |
Hines, Sophia K. V. Southon, John R. Adkins, Jess F. |
spellingShingle |
Hines, Sophia K. V. Southon, John R. Adkins, Jess F. A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years |
author_facet |
Hines, Sophia K. V. Southon, John R. Adkins, Jess F. |
author_sort |
Hines, Sophia K. V. |
title |
A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years |
title_short |
A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years |
title_full |
A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years |
title_fullStr |
A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years |
title_full_unstemmed |
A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years |
title_sort |
high-resolution record of southern ocean intermediate water radiocarbon over the past 30,000 years |
publisher |
Elsevier |
publishDate |
2015 |
url |
https://authors.library.caltech.edu/61966/ https://authors.library.caltech.edu/61966/2/mmc4.pdf https://authors.library.caltech.edu/61966/3/mmc5.pdf https://resolver.caltech.edu/CaltechAUTHORS:20151106-150028884 |
geographic |
Antarctic Drake Passage Greenland Pacific Southern Ocean The Antarctic |
geographic_facet |
Antarctic Drake Passage Greenland Pacific Southern Ocean The Antarctic |
genre |
Antarc* Antarctic Drake Passage Greenland Greenland ice core ice core Southern Ocean |
genre_facet |
Antarc* Antarctic Drake Passage Greenland Greenland ice core ice core Southern Ocean |
op_relation |
https://authors.library.caltech.edu/61966/2/mmc4.pdf https://authors.library.caltech.edu/61966/3/mmc5.pdf Hines, Sophia K. V. and Southon, John R. and Adkins, Jess F. (2015) A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years. Earth and Planetary Science Letters, 432 . pp. 46-58. ISSN 0012-821X. doi:10.1016/j.epsl.2015.09.038. https://resolver.caltech.edu/CaltechAUTHORS:20151106-150028884 <https://resolver.caltech.edu/CaltechAUTHORS:20151106-150028884> |
op_rights |
other |
op_doi |
https://doi.org/10.1016/j.epsl.2015.09.038 |
container_title |
Earth and Planetary Science Letters |
container_volume |
432 |
container_start_page |
46 |
op_container_end_page |
58 |
_version_ |
1766264863350325248 |