Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation
Abstract Recent analysis of a sediment core in the eastern Arabian Sea revealed a negative pulse of about 1% in the δ 18 O value of the planktonic Foraminifera around the last glacial maximum (LGM). This pulse has been attributed to (i) increased runoff into the Bay of Bengal from the east‐flowing s...
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crwiley:10.1002/jqs.3390070306 2024-06-02T08:13:26+00:00 Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation Gupta, S. K. Sharma, P. Shah, S. K. 1992 http://dx.doi.org/10.1002/jqs.3390070306 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.3390070306 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.3390070306 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Journal of Quaternary Science volume 7, issue 3, page 247-255 ISSN 0267-8179 1099-1417 journal-article 1992 crwiley https://doi.org/10.1002/jqs.3390070306 2024-05-03T11:37:07Z Abstract Recent analysis of a sediment core in the eastern Arabian Sea revealed a negative pulse of about 1% in the δ 18 O value of the planktonic Foraminifera around the last glacial maximum (LGM). This pulse has been attributed to (i) increased runoff into the Bay of Bengal from the east‐flowing south Indian rivers due to enhancement of the northeast winter monsoon, and (ii) an increase in Arabian sea‐surface temperature caused by the weakening of the southwest monsoon at the LGM. We show that the speculation on which the latter hypothesis is based, is not supported by observational data and cannot fully account for the observed magnitude of the spike. With a view to assessing the validity of the first mechanism, we have modelled the mixed layer of the Bay of Bengal as a well‐mixed box. The model calculations show that to account for the pulse requires a change of about 10% in either the annual rate of river input or its isotopic composition. For the northeast monsoon to account for the pulse it would mean that the rainfall should have increased by a factor of five to ten during the LGM. No evidence for such an increase is indicated in the available palaeoclimatic data. We explain the freshwater spike by invoking increased discharge of glacial meltwater from the Tibetan plateau into the Bay of Bengal. We show that the proxy climate data from the Indo‐Tibetan region that has become available recently provides substantial evidence for the occurrence of a warming event around the LGM, which supports our mechanism. Article in Journal/Newspaper Planktonic foraminifera Wiley Online Library Indian The Spike ENVELOPE(-37.317,-37.317,-54.017,-54.017) Journal of Quaternary Science 7 3 247 255 |
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Open Polar |
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Wiley Online Library |
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crwiley |
language |
English |
description |
Abstract Recent analysis of a sediment core in the eastern Arabian Sea revealed a negative pulse of about 1% in the δ 18 O value of the planktonic Foraminifera around the last glacial maximum (LGM). This pulse has been attributed to (i) increased runoff into the Bay of Bengal from the east‐flowing south Indian rivers due to enhancement of the northeast winter monsoon, and (ii) an increase in Arabian sea‐surface temperature caused by the weakening of the southwest monsoon at the LGM. We show that the speculation on which the latter hypothesis is based, is not supported by observational data and cannot fully account for the observed magnitude of the spike. With a view to assessing the validity of the first mechanism, we have modelled the mixed layer of the Bay of Bengal as a well‐mixed box. The model calculations show that to account for the pulse requires a change of about 10% in either the annual rate of river input or its isotopic composition. For the northeast monsoon to account for the pulse it would mean that the rainfall should have increased by a factor of five to ten during the LGM. No evidence for such an increase is indicated in the available palaeoclimatic data. We explain the freshwater spike by invoking increased discharge of glacial meltwater from the Tibetan plateau into the Bay of Bengal. We show that the proxy climate data from the Indo‐Tibetan region that has become available recently provides substantial evidence for the occurrence of a warming event around the LGM, which supports our mechanism. |
format |
Article in Journal/Newspaper |
author |
Gupta, S. K. Sharma, P. Shah, S. K. |
spellingShingle |
Gupta, S. K. Sharma, P. Shah, S. K. Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation |
author_facet |
Gupta, S. K. Sharma, P. Shah, S. K. |
author_sort |
Gupta, S. K. |
title |
Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation |
title_short |
Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation |
title_full |
Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation |
title_fullStr |
Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation |
title_full_unstemmed |
Source of a freshwater influx at the last glacial maximum in the Indian Ocean: An alternative interpretation |
title_sort |
source of a freshwater influx at the last glacial maximum in the indian ocean: an alternative interpretation |
publisher |
Wiley |
publishDate |
1992 |
url |
http://dx.doi.org/10.1002/jqs.3390070306 https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjqs.3390070306 https://onlinelibrary.wiley.com/doi/pdf/10.1002/jqs.3390070306 |
long_lat |
ENVELOPE(-37.317,-37.317,-54.017,-54.017) |
geographic |
Indian The Spike |
geographic_facet |
Indian The Spike |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_source |
Journal of Quaternary Science volume 7, issue 3, page 247-255 ISSN 0267-8179 1099-1417 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/jqs.3390070306 |
container_title |
Journal of Quaternary Science |
container_volume |
7 |
container_issue |
3 |
container_start_page |
247 |
op_container_end_page |
255 |
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1800736952767479808 |