Atmosphere-driven ice sheet mass loss paced by topography: Insights from modelling the south-western Scandinavian Ice Sheet

QUATERNARY SCIENCE REVIEWS

卷:195

Article

Akesson, Henning^1,2  Morlighem, Mathieu³  Nisancioglu, Kerim H.^1,2,4  Svendsen, John Inge^1,2  Mangerud, Jan^1,2 

[1] Univ Bergen, Dept Earth Sci, Allegaten 70, N-5007 Bergen, Norway

[2] Bjerknes Ctr Climate Res, Allegaten 70, N-5007 Bergen, Norway

[3] Univ Calif Irvine, Dept Earth Syst Sci, 3218 Croul Hall, Irvine, CA 92697 USA

[4] Univ Oslo, Ctr Earth Evolut & Dynam, Postbox 1028 Blindern, N-0315 Oslo, Norway

关键词: Ice sheet modelling;    Grounding line dynamics;    Marine-terminating glaciers;    Deglaciation;    Ice-ocean interactions;    Surface mass balance;    Younger dryas;    Norway;    Eurasian ice sheet;    Scandinavian ice sheet;   

DOI  :  10.1016/j.quascirev.2018.07.004

来源: Elsevier

【 摘 要 】

Marine-terminating glaciers and ice streams are important controls of ice sheet mass balance. However, understanding of their long-term response to external forcing is limited by relatively short observational records of present-day glaciers and sparse geologic evidence for paleo-glaciers. Here we use a high resolution ice sheet model with an accurate representation of grounding line dynamics to study the deglaciation of the marine-based south-western Norwegian sector of the Scandinavian Ice Sheet and its sensitivity to ocean and atmosphere forcing. We find that the regional response to a uniform climate change is highly dependent on the local bedrock topography, consistent with ice sheet reconstructions. Our simulations suggest that ocean warming is able to trigger initial retreat in several fiords, but is not sufficient to explain retreat everywhere. Widespread retreat requires additional ice thinning driven by surface melt. Once retreat is triggered, the underlying bedrock topography and fjord width control the rate and extent of retreat, while multi-millennial changes over the course of deglaciation are modulated by surface melt. We suggest that fjord geometry, ice-ocean interactions and grounding line dynamics are vital controls of decadal-to centennial scale ice sheet mass loss. However, we postulate that atmospheric changes are the most important drivers of widespread ice sheet demise, and will likely trump oceanic influence on future ice sheet mass loss and resulting sea level rise over centennial and longer time scales. (C) 2018 The Authors. Published by Elsevier Ltd.

【 授权许可】

Free