Antarctic ice-sheet response to atmospheric CO 2 and insolation in the Middle Miocene
Foraminiferal oxygen isotopes from deep-sea sediment cores suggest that a rapid expansion of the Antarctic ice sheet took place in the Middle Miocene around 13.9 million years ago. The origin for this transition is still not understood satisfactorily. One possible cause is a drop in the partial pres...
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ftdoajarticles:oai:doaj.org/article:41b3c1b6a30741f683613d9bf1a9b81e 2023-05-15T13:40:09+02:00 Antarctic ice-sheet response to atmospheric CO 2 and insolation in the Middle Miocene M. Schulz A. Paul P. M. Langebroek 2009-10-01T00:00:00Z https://doaj.org/article/41b3c1b6a30741f683613d9bf1a9b81e EN eng Copernicus Publications http://www.clim-past.net/5/633/2009/cp-5-633-2009.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 https://doaj.org/article/41b3c1b6a30741f683613d9bf1a9b81e Climate of the Past, Vol 5, Iss 4, Pp 633-646 (2009) Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 article 2009 ftdoajarticles 2022-12-31T13:24:40Z Foraminiferal oxygen isotopes from deep-sea sediment cores suggest that a rapid expansion of the Antarctic ice sheet took place in the Middle Miocene around 13.9 million years ago. The origin for this transition is still not understood satisfactorily. One possible cause is a drop in the partial pressure of atmospheric carbon dioxide ( p CO 2 ) in combination with orbital forcing. A complication is the large uncertainty in the magnitude and timing of the reconstructed p CO 2 variability and additionally the low temporal resolution of the available p CO 2 records in the Middle Miocene. We used an ice sheet-climate model of reduced complexity to assess variations in Antarctic ice sheet volume induced by p CO 2 and insolation forcing in the Middle Miocene. The ice-sheet sensitivity to atmospheric CO 2 was tested for several scenarios with constant p CO 2 forcing or a regular decrease in p CO 2 . This showed that small, ephemeral ice sheets existed under relatively high atmospheric CO 2 conditions (between 640–900 ppm), whereas more stable, large ice sheets occurred when p CO 2 was less than ~600 ppm. The main result of this study is that the p CO 2 -level must have declined just before or during the period of oxygen-isotope increase, thereby crossing a p CO 2 glaciation threshold of around 615 ppm. After the decline, the exact timing of the Antarctic ice-sheet expansion depends also on the relative minimum in summer insolation at approximately 13.89 million years ago. Although the mechanisms described appear to be robust, the exact values of the p CO 2 thresholds are likely to be model-dependent. Article in Journal/Newspaper Antarc* Antarctic Ice Sheet Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
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 M. Schulz A. Paul P. M. Langebroek Antarctic ice-sheet response to atmospheric CO 2 and insolation in the Middle Miocene |
topic_facet |
Environmental pollution TD172-193.5 Environmental protection TD169-171.8 Environmental sciences GE1-350 |
description |
Foraminiferal oxygen isotopes from deep-sea sediment cores suggest that a rapid expansion of the Antarctic ice sheet took place in the Middle Miocene around 13.9 million years ago. The origin for this transition is still not understood satisfactorily. One possible cause is a drop in the partial pressure of atmospheric carbon dioxide ( p CO 2 ) in combination with orbital forcing. A complication is the large uncertainty in the magnitude and timing of the reconstructed p CO 2 variability and additionally the low temporal resolution of the available p CO 2 records in the Middle Miocene. We used an ice sheet-climate model of reduced complexity to assess variations in Antarctic ice sheet volume induced by p CO 2 and insolation forcing in the Middle Miocene. The ice-sheet sensitivity to atmospheric CO 2 was tested for several scenarios with constant p CO 2 forcing or a regular decrease in p CO 2 . This showed that small, ephemeral ice sheets existed under relatively high atmospheric CO 2 conditions (between 640–900 ppm), whereas more stable, large ice sheets occurred when p CO 2 was less than ~600 ppm. The main result of this study is that the p CO 2 -level must have declined just before or during the period of oxygen-isotope increase, thereby crossing a p CO 2 glaciation threshold of around 615 ppm. After the decline, the exact timing of the Antarctic ice-sheet expansion depends also on the relative minimum in summer insolation at approximately 13.89 million years ago. Although the mechanisms described appear to be robust, the exact values of the p CO 2 thresholds are likely to be model-dependent. |
format |
Article in Journal/Newspaper |
author |
M. Schulz A. Paul P. M. Langebroek |
author_facet |
M. Schulz A. Paul P. M. Langebroek |
author_sort |
M. Schulz |
title |
Antarctic ice-sheet response to atmospheric CO 2 and insolation in the Middle Miocene |
title_short |
Antarctic ice-sheet response to atmospheric CO 2 and insolation in the Middle Miocene |
title_full |
Antarctic ice-sheet response to atmospheric CO 2 and insolation in the Middle Miocene |
title_fullStr |
Antarctic ice-sheet response to atmospheric CO 2 and insolation in the Middle Miocene |
title_full_unstemmed |
Antarctic ice-sheet response to atmospheric CO 2 and insolation in the Middle Miocene |
title_sort |
antarctic ice-sheet response to atmospheric co 2 and insolation in the middle miocene |
publisher |
Copernicus Publications |
publishDate |
2009 |
url |
https://doaj.org/article/41b3c1b6a30741f683613d9bf1a9b81e |
geographic |
Antarctic The Antarctic |
geographic_facet |
Antarctic The Antarctic |
genre |
Antarc* Antarctic Ice Sheet |
genre_facet |
Antarc* Antarctic Ice Sheet |
op_source |
Climate of the Past, Vol 5, Iss 4, Pp 633-646 (2009) |
op_relation |
http://www.clim-past.net/5/633/2009/cp-5-633-2009.pdf https://doaj.org/toc/1814-9324 https://doaj.org/toc/1814-9332 1814-9324 1814-9332 https://doaj.org/article/41b3c1b6a30741f683613d9bf1a9b81e |
_version_ |
1766128656252403712 |