Sea ice feedbacks influence the isotopic signature of Greenland ice sheet elevation changes: Last interglacial HadCM3 simulations

Malmierca-Vallet, Irene ORCID: https://orcid.org/0000-0002-2871-9741; Sime, Louise C. ORCID: https://orcid.org/0000-0002-9093-7926; Valdes, Paul J.; Tindall, Julia C.. 2020 Sea ice feedbacks influence the isotopic signature of Greenland ice sheet elevation changes: Last interglacial HadCM3 simulations. Climate of the Past, 16 (6). 2485-2508. https://doi.org/10.5194/cp-16-2485-2020

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Abstract/Summary

Changes in the Greenland ice sheet (GIS) affect global sea level. Greenland stable water isotope (δ18O) records from ice cores offer information on past changes in the surface of the GIS. Here, we use the isotope-enabled Hadley Centre Coupled Model version 3 (HadCM3) climate model to simulate a set of last interglacial (LIG) idealised GIS surface elevation change scenarios focusing on GIS ice core sites. We investigate how δ18O depends on the magnitude and sign of GIS elevation change and evaluate how the response is altered by sea ice changes. We find that modifying GIS elevation induces changes in Northern Hemisphere atmospheric circulation, sea ice and precipitation patterns. These climate feedbacks lead to ice-core-averaged isotopic lapse rates of 0.49 ‰ (100 m)−1 for the lowered GIS states and 0.29 ‰ (100 m)−1 for the enlarged GIS states. This is lower than the spatially derived Greenland lapse rates of 0.62–0.72 ‰ (100 m)−1. These results thus suggest non-linearities in the isotope–elevation relationship and have consequences for the interpretation of past elevation and climate changes across Greenland. In particular, our results suggest that winter sea ice changes may significantly influence isotope–elevation gradients: winter sea ice effect can decrease (increase) modelled core-averaged isotopic lapse rate values by about −19 % (and +28 %) for the lowered (enlarged) GIS states, respectively. The largest influence of sea ice on δ18O changes is found in coastal regions like the Camp Century site.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.5194/cp-16-2485-2020
ISSN:	1814-9324
Date made live:	21 Apr 2020 09:54 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/527524

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.5194/cp-16-2485-2020

ISSN:

1814-9324

Date made live:

21 Apr 2020 09:54 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/527524