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Persistent influence of ice sheet melting on high northern latitude climate during the early Last Interglacial

Govin, A.; Braconnot, P.; Capron, E.; Cortijo, E.; Duplessy, J.-C.; Jansen, E.; Labeyrie, L.; Landais, A.; Marti, O.; Michel, E.; Mosquet, E.; Risebrobakken, B.; Swingedouw, D.; Waelbroeck, C.. 2012 Persistent influence of ice sheet melting on high northern latitude climate during the early Last Interglacial. Climate of the Past, 8 (2). 483-507. 10.5194/cp-8-483-2012

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Abstract/Summary

Although the Last Interglacial (LIG) is often considered as a possible analogue for future climate in high latitudes, its precise climate evolution and associated causes remain uncertain. Here we compile high-resolution marine sediment records from the North Atlantic, Labrador Sea, Norwegian Sea and the Southern Ocean. We document a delay in the establishment of peak interglacial conditions in the North Atlantic, Labrador and Norwegian Seas as compared to the Southern Ocean. In particular, we observe a persistent iceberg melting at high northern latitudes at the beginning of the LIG. It is associated with (1) colder and fresher surface-water conditions in the North Atlantic, Labrador and Norwegian Seas, and (2) a weaker ventilation of North Atlantic deep waters during the early LIG (129–125 ka) compared to the late LIG. Results from an ocean-atmosphere coupled model with insolation as a sole forcing for three key periods of the LIG show warmer North Atlantic surface waters and stronger Atlantic overturning during the early LIG (126 ka) than the late LIG (122 ka). Hence, insolation variations alone do not explain the delay in peak interglacial conditions observed at high northern latitudes. Additionally, we consider an idealized meltwater scenario at 126 ka where the freshwater input is interactively computed in response to the high boreal summer insolation. The model simulates colder, fresher North Atlantic surface waters and weaker Atlantic overturning during the early LIG (126 ka) compared to the late LIG (122 ka). This result suggests that both insolation and ice sheet melting have to be considered to reproduce the climatic pattern that we identify during the early LIG. Our model-data comparison also reveals a number of limitations and reinforces the need for further detailed investigations using coupled climate-ice sheet models and transient simulations.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.5194/cp-8-483-2012
Programmes: BAS Programmes > Polar Science for Planet Earth (2009 - ) > Chemistry and Past Climate
ISSN: 1814-9332
Additional Information. Not used in RCUK Gateway to Research.: This work is distributed under the Creative Commons Attribution 3.0 License together with an author copyright. This license does not conflict with the regulations of the Crown Copyright.
Date made live: 08 Apr 2013 14:06 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/500924

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