Linear response of east Greenland's tidewater glaciers to ocean/atmosphere warming

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Cowton, T.R., Sole, A.J., Nienow, P.W., Slater, D.A., Christoffersen, P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Academy of Sciences 2018
• Subjects: Greenland; glacier; Ice Sheet; Tidewater
• Online Access: https://eprints.whiterose.ac.uk/133634/; https://eprints.whiterose.ac.uk/133634/1/Revised%20manuscript%20ACCEPTED.pdf; https://doi.org/10.1073/pnas.1801769115

Predicting the retreat of tidewater outlet glaciers forms a major obstacle to forecasting the rate of mass loss from the Greenland Ice Sheet. This reflects the challenges of modeling the highly dynamic, topographically complex, and data-poor environment of the glacier-fjord systems that link the ice sheet to the ocean. To avoid these difficulties, we investigate the extent to which tidewater glacier retreat can be explained by simple variables: air temperature, meltwater runoff, ocean temperature, and two simple parameterizations of "ocean/atmosphere" forcing based on the combined influence of runoff and ocean temperature. Over a 20-y period at 10 large tidewater outlet glaciers along the east coast of Greenland, we find that ocean/atmosphere forcing can explain up to 76% of the variability in terminus position at individual glaciers and 54% of variation in terminus position across all 10 glaciers. Our findings indicate that (i) the retreat of east Greenland's tidewater glaciers is best explained as a product of both oceanic and atmospheric warming and (ii) despite the complexity of tidewater glacier behavior, over multiyear timescales a significant proportion of terminus position change can be explained as a simple function of this forcing. These findings thus demonstrate that simple parameterizations can play an important role in predicting the response of the ice sheet to future climate warming.