Effects of extreme melt events on ice flow and sea level rise of the Greenland Ice Sheet

IF 4.4 2区地球科学 Q1 GEOGRAPHY, PHYSICAL

Cryosphere Pub Date : 2023-07-27 DOI:10.5194/tc-17-3083-2023

J. Beckmann, R. Winkelmann

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引用次数: 2

Abstract

Abstract. Over the past decade, Greenland has experienced several extreme melt events, the most pronounced ones in the years 2010, 2012 and 2019. With progressing climate change, such extreme melt events can be expected to occur more frequently and potentially become more severe and persistent. So far, however, projections of ice loss and sea level change from Greenland typically rely on scenarios which only take gradual changes in the climate into account. Using the Parallel Ice Sheet Model (PISM), we investigate the effect of extreme melt events on the overall mass balance of the Greenland Ice Sheet and the changes in ice flow, invoked by the altered surface topography. As a first constraint, this study estimates the overall effect of extreme melt events on the cumulative mass loss of the Greenland Ice Sheet. We find that the sea level contribution from Greenland might increase by 2 to 45 cm (0.2 % to 14 %) by the year 2300 if extreme events occur more frequently in the future under a Representative Concentration Pathway 8.5 (RCP8.5) scenario, and the ice sheet area might be reduced by an additional 6000 to 26 000 km2 by 2300 in comparison to future warming scenarios without extremes. In conclusion, projecting the future sea level contribution from the Greenland Ice Sheet requires consideration of the changes in both the frequency and intensity of extreme events. It is crucial to individually address these extremes at a monthly resolution as temperature forcing with the same excess temperature but evenly distributed over longer timescales (e.g., seasonal) leads to less sea level rise than for the simulations of the resolved extremes. Extremes lead to additional mass loss and thinning. This, in turn, reduces the driving stress and surface velocities, ultimately dampening the ice loss attributed to ice flow and discharge. Overall, we find that the surface elevation feedback largely amplifies melting for scenarios with and without extremes, with additional mass loss attributed to this feedback having the greatest impact on projected sea level.

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极端融化事件对格陵兰冰盖冰流和海平面上升的影响

摘要在过去的十年里，格陵兰岛经历了几次极端的融化事件，最明显的是在2010年、2012年和2019年。随着气候变化的加剧，这种极端的融化事件预计会更频繁地发生，并可能变得更加严重和持续。然而，到目前为止，格陵兰岛的冰损失和海平面变化的预测通常依赖于只考虑气候逐渐变化的情景。利用平行冰盖模式(PISM)，我们研究了极端融化事件对格陵兰冰盖整体质量平衡的影响，以及由地表地形变化引起的冰流变化。作为第一个约束条件，本研究估计了极端融化事件对格陵兰冰盖累积质量损失的总体影响。我们发现，在代表性浓度路径8.5 (RCP8.5)情景下，如果极端事件在未来更频繁地发生，到2300年，格陵兰岛对海平面的贡献可能会增加2至45厘米(0.2%至14%)，到2300年，与没有极端事件的未来变暖情景相比，冰盖面积可能会额外减少6000至26000平方公里。总之，预测格陵兰冰盖对未来海平面的贡献需要考虑极端事件频率和强度的变化。以月为分辨率单独处理这些极端事件是至关重要的，因为具有相同超额温度但在较长时间尺度上均匀分布的温度强迫(例如，季节)导致的海平面上升幅度小于模拟已解决的极端事件。极端情况导致更多的质量损失和变薄。这反过来又降低了驱动应力和表面速度，最终抑制了冰流和冰排放造成的冰损失。总的来说，我们发现，无论有没有极端情况，地表高度反馈都在很大程度上放大了融化，由于这种反馈造成的额外质量损失对预估海平面的影响最大。

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

Cryosphere GEOGRAPHY, PHYSICAL-GEOSCIENCES, MULTIDISCIPLINARY

CiteScore

8.70

自引率

17.30%

发文量

240

审稿时长

4-8 weeks

期刊介绍： The Cryosphere (TC) is a not-for-profit international scientific journal dedicated to the publication and discussion of research articles, short communications, and review papers on all aspects of frozen water and ground on Earth and on other planetary bodies. The main subject areas are the following: ice sheets and glaciers; planetary ice bodies; permafrost and seasonally frozen ground; seasonal snow cover; sea ice; river and lake ice; remote sensing, numerical modelling, in situ and laboratory studies of the above and including studies of the interaction of the cryosphere with the rest of the climate system.