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

Sime, Louise ORCID: https://orcid.org/0000-0002-9093-7926; Hopcroft, Peter O.; Rhodes, Rachael H.. 2019 Impact of abrupt sea ice loss on Greenland water isotopes during the last glacial period. Proceedings of the National Academy of Sciences of the United States of America, 116 (10). 4099-4104. 10.1073/pnas.1807261116

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Text Copyright © 2019 the Author(s). Published by PNAS. This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY) Sime.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (1MB) | Preview

Abstract/Summary

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 (δ18O) 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 δ18O: 95% of the variability in δ18O 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 δ18O 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 δ18O paleothermometer to the magnitude of DO event temperature increase: the change in δ18O per Kelvin temperature increase reduces with DO event amplitude. We show that this effect is controlled by precipitation seasonality.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1073/pnas.1807261116
ISSN:	17520894
Additional Keywords:	abrupt warmings, climate change, Arctic, sea ice, paleoclimate
Date made live:	28 Feb 2019 16:34 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/519752

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