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Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period

Greenland ice cores provide excellent evidence of past abrupt climate changes. However, there is no universally accepted theory of how and why these Dansgaard–Oeschger (DO) events occur. Several mechanisms have been proposed to explain DO events, including sea ice, ice shelf buildup, ice sheets, atm...

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Detalles Bibliográficos
Autores principales: Sime, Louise C., Hopcroft, Peter O., Rhodes, Rachael H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6410777/
https://www.ncbi.nlm.nih.gov/pubmed/30760586
http://dx.doi.org/10.1073/pnas.1807261116
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author Sime, Louise C.
Hopcroft, Peter O.
Rhodes, Rachael H.
author_facet Sime, Louise C.
Hopcroft, Peter O.
Rhodes, Rachael H.
author_sort Sime, Louise C.
collection PubMed
description Greenland ice cores provide excellent evidence of past abrupt climate changes. However, there is no universally accepted theory of how and why these Dansgaard–Oeschger (DO) events occur. Several mechanisms have been proposed to explain DO events, including sea ice, ice shelf buildup, ice sheets, atmospheric circulation, and meltwater changes. DO event temperature reconstructions depend on the stable water isotope ([Formula: see text] O) and nitrogen isotope measurements from Greenland ice cores: interpretation of these measurements holds the key to understanding the nature of DO events. Here, we demonstrate the primary importance of sea ice as a control on Greenland ice core [Formula: see text] O: 95% of the variability in [Formula: see text] O in southern Greenland is explained by DO event sea ice changes. Our suite of DO events, simulated using a general circulation model, accurately captures the amplitude of [Formula: see text] O enrichment during the abrupt DO event onsets. Simulated geographical variability is broadly consistent with available ice core evidence. We find an hitherto unknown sensitivity of the [Formula: see text] O paleothermometer to the magnitude of DO event temperature increase: the change in [Formula: see text] O per Kelvin temperature increase reduces with DO event amplitude. We show that this effect is controlled by precipitation seasonality.
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spelling pubmed-64107772019-03-13 Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period Sime, Louise C. Hopcroft, Peter O. Rhodes, Rachael H. Proc Natl Acad Sci U S A Physical Sciences Greenland ice cores provide excellent evidence of past abrupt climate changes. However, there is no universally accepted theory of how and why these Dansgaard–Oeschger (DO) events occur. Several mechanisms have been proposed to explain DO events, including sea ice, ice shelf buildup, ice sheets, atmospheric circulation, and meltwater changes. DO event temperature reconstructions depend on the stable water isotope ([Formula: see text] O) and nitrogen isotope measurements from Greenland ice cores: interpretation of these measurements holds the key to understanding the nature of DO events. Here, we demonstrate the primary importance of sea ice as a control on Greenland ice core [Formula: see text] O: 95% of the variability in [Formula: see text] O in southern Greenland is explained by DO event sea ice changes. Our suite of DO events, simulated using a general circulation model, accurately captures the amplitude of [Formula: see text] O enrichment during the abrupt DO event onsets. Simulated geographical variability is broadly consistent with available ice core evidence. We find an hitherto unknown sensitivity of the [Formula: see text] O paleothermometer to the magnitude of DO event temperature increase: the change in [Formula: see text] O per Kelvin temperature increase reduces with DO event amplitude. We show that this effect is controlled by precipitation seasonality. National Academy of Sciences 2019-03-05 2019-02-13 /pmc/articles/PMC6410777/ /pubmed/30760586 http://dx.doi.org/10.1073/pnas.1807261116 Text en Copyright © 2019 the Author(s). Published by PNAS. http://creativecommons.org/licenses/by/4.0/ This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY) (http://creativecommons.org/licenses/by/4.0/) .
spellingShingle Physical Sciences
Sime, Louise C.
Hopcroft, Peter O.
Rhodes, Rachael H.
Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period
title Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period
title_full Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period
title_fullStr Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period
title_full_unstemmed Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period
title_short Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period
title_sort impact of abrupt sea ice loss on greenland water isotopes during the last glacial period
topic Physical Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6410777/
https://www.ncbi.nlm.nih.gov/pubmed/30760586
http://dx.doi.org/10.1073/pnas.1807261116
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