Northern Hemisphere ice sheets and ocean interactions during the last glacial period in a coupled ice sheet-climate model

IF 3.8 2区地球科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Climate of The Past Pub Date : 2024-08-07 DOI:10.5194/cp-2024-51

Louise Abot, Aurélien Quiquet, Claire Waelbroeck

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Abstract

Abstract. This study examines the interactions between the Northern Hemisphere ice sheets and the ocean during the last glacial period. We explore the consequences of an ocean subsurface warming on ice sheet dynamics and the associated feedbacks, using the climate model of intermediate complexity iLOVECLIM coupled with the ice sheet model GRISLI. Our study shows that amplified oceanic basal melt rates lead to significant freshwater release from both increased calving and basal melt fluxes. Inland, dynamic thinning occurs over the Eurasian and Iceland ice sheets, leading to destabilization, while the coasts of Greenland and the eastern part of the Laurentide ice sheet are thickening. There, the increased oceanic basal melt rates lead to a reduction in the thickness of the ice shelves and the ice flow at the grounding line, resulting in upstream accumulation. Nevertheless, the influx of fresh water temporarily increases sea-ice extent, reduces convection in the Labrador Sea, weakens the Atlantic meridional overturning circulation, lowers surface temperatures in the Northern Hemisphere and increases the subsurface temperatures in the Nordic Seas. The release of cold and fresh water leads to a decrease in ice sheet discharge (negative feedback) for the Greenland and Eurasian ice sheets. The Laurentide ice sheet is rather stable due to low background temperatures and salinity at shelf drafts in the Baffin Bay and Labrador Sea in the model. Still, we show that we are able to trigger a grounding line retreat by imposing ad-hoc oceanic melt rates (10 m/yr). However, continental ice loss stops as soon as we halt the perturbation. This study emphasizes the complex feedback mechanisms at the ocean-ice sheet interface, stressing the necessity for more accurately constrained model results to enhance our understanding of past changes and the predictions of future ice sheet behaviour and sea level rise.

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冰盖-气候耦合模型中末次冰川期北半球冰盖与海洋的相互作用

摘要本研究探讨了上一个冰川期北半球冰盖与海洋之间的相互作用。我们利用中等复杂程度的气候模式 iLOVECLIM 和冰盖模式 GRISLI，探讨了海洋表层下变暖对冰盖动力学和相关反馈的影响。我们的研究表明，海洋基底融化率的扩大导致冰盖形成和基底融化通量的增加，从而导致大量淡水释放。在内陆，欧亚冰盖和冰岛冰盖发生动态减薄，导致不稳定，而格陵兰岛海岸和劳伦泰德峰冰盖东部则在增厚。在这些地方，海洋基底融化率的增加导致冰架厚度和接地线冰流的减少，从而造成上游的积聚。然而，淡水的涌入暂时增加了海冰范围，减少了拉布拉多海的对流，削弱了大西洋经向翻转环流，降低了北半球的地表温度，增加了北欧海域的地下温度。冷水和淡水的释放导致格陵兰和欧亚冰原的冰排减少（负反馈）。由于模型中巴芬湾和拉布拉多海大陆架吃水处的背景温度和盐度较低，劳伦泰德冰盖相当稳定。不过，我们的研究表明，通过施加临时的海洋融化率（10 米/年），我们能够触发接地线后退。然而，一旦我们停止扰动，大陆冰损失就会停止。这项研究强调了海洋-冰盖界面上复杂的反馈机制，强调有必要对模型结果进行更精确的约束，以加强我们对过去变化的理解，以及对未来冰盖行为和海平面上升的预测。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Climate of The Past 地学-气象与大气科学

CiteScore

7.40

自引率

14.00%

发文量

120

审稿时长

4-8 weeks

期刊介绍： Climate of the Past (CP) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on the climate history of the Earth. CP covers all temporal scales of climate change and variability, from geological time through to multidecadal studies of the last century. Studies focusing mainly on present and future climate are not within scope. The main subject areas are the following: reconstructions of past climate based on instrumental and historical data as well as proxy data from marine and terrestrial (including ice) archives; development and validation of new proxies, improvements of the precision and accuracy of proxy data; theoretical and empirical studies of processes in and feedback mechanisms between all climate system components in relation to past climate change on all space scales and timescales; simulation of past climate and model-based interpretation of palaeoclimate data for a better understanding of present and future climate variability and climate change.