Greenland ice mass loss during the Younger Dryas driven by Atlantic Meridional Overturning Circulation feedbacks

Understanding feedbacks between the Greenland Ice Sheet (GrIS) and the Atlantic Meridional Overturning Circulation (AMOC) is crucial for reducing uncertainties over future sea level and ocean circulation change. Reconstructing past GrIS dynamics can extend the observational record and elucidate mech...

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Bibliographic Details
Published in:Scientific Reports
Main Authors: Rainsley, E, Menviel, L, Fogwill, CJ, Turney, CSM, Hughes, ALC, Rood, DH
Format: Article in Journal/Newspaper
Language:English
Published: NATURE PUBLISHING GROUP 2018
Subjects:
Science & Technology
Multidisciplinary Sciences
Science & Technology - Other Topics
PRODUCTION-RATE CALIBRATION
LAST GLACIAL TERMINATION
SOUTHEAST GREENLAND
EAST GREENLAND
WEST GREENLAND
JAKOBSHAVN ISBRAE
PRODUCTION-RATES
CLIMATIC CHANGES
HELHEIM GLACIER
OUTLET GLACIERS
Greenland
East Greenland
glacier
Ice Sheet
Jakobshavn
North Atlantic
Sermilik
Online Access:http://hdl.handle.net/10044/1/64540
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000441159000001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
https://doi.org/10.1038/s41598-018-29226-8
Description
Summary:Understanding feedbacks between the Greenland Ice Sheet (GrIS) and the Atlantic Meridional Overturning Circulation (AMOC) is crucial for reducing uncertainties over future sea level and ocean circulation change. Reconstructing past GrIS dynamics can extend the observational record and elucidate mechanisms that operate on multi-decadal timescales. We report a highly-constrained last glacial vertical profile of cosmogenic isotope exposure ages from Sermilik Fjord, a marine-terminating ice stream in the southeast sector of the GrIS. Our reconstruction reveals substantial ice-mass loss throughout the Younger Dryas (12.9-11.7 ka), a period of marked atmospheric and sea-surface cooling. Earth-system modelling reveals that southern GrIS marginal melt was likely driven by strengthening of the Irminger Current at depth due to a weakening of the AMOC during the Younger Dryas. This change in North Atlantic circulation appears to have drawn warm subsurface waters to southeast Greenland despite markedly cooler sea surface temperatures, enhancing thermal erosion at the grounding lines of palaeo ice-streams, supporting interpretation of regional marine-sediment cores. Given current rates of GrIS meltwater input into the North Atlantic and the vulnerability of major ice streams to water temperature changes at the grounding line, this mechanism has important implications for future AMOC changes and northern hemisphere heat transport.

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