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

Rainsley, E., Menviel, L., Fogwill, C. J., Turney, C. S.M., Hughes, A. L.C. and Rood, D. H. (2018) Greenland ice mass loss during the Younger Dryas driven by Atlantic Meridional Overturning Circulation feedbacks. Scientific Reports, 8, 11307. (doi: 10.1038/s41598-018-29226-8) (PMID:30093676) (PMCID:PMC6085367)

Abstract

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.

• Item Type: Articles
• Additional Information: The newly-reported dates were funded by the Royal Society (London; Fogwill, RG080557), as was part of the fieldwork. LM is supported by the Australian Research Council through grant DE150100107. Hughes and part of the fieldwork were funded by the Leverhulme Trust GLIMPSE Project F/00391/J.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Rood, Dr Dylan
• Authors: Rainsley, E., Menviel, L., Fogwill, C. J., Turney, C. S.M., Hughes, A. L.C., and Rood, D. H.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Scientific Reports
• Publisher: Nature Research
• ISSN: 2045-2322
• ISSN (Online): 2045-2322
• Copyright Holders: Copyright © 2018 The Authors
• First Published: First published in Scientific Reports 8: 11307
• Publisher Policy: Reproduced under a Creative Commons License