Stability of Ice Shelves and Ice Cliffs in a Changing Climate

IF 11.3 1区地球科学 Q1 ASTRONOMY & ASTROPHYSICS

Annual Review of Earth and Planetary Sciences Pub Date : 2024-01-12 DOI:10.1146/annurev-earth-040522-122817

Jeremy N. Bassis, Anna Crawford, Samuel B. Kachuck, Douglas I. Benn, Catherine Walker, Joanna Millstein, Ravindra Duddu, Jan Åström, Helen Fricker, Adrian Luckman

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引用次数: 0

Abstract

The largest uncertainty in future sea-level rise is loss of ice from the Greenland and Antarctic Ice Sheets. Ice shelves, freely floating platforms of ice that fringe the ice sheets, play a crucial role in restraining discharge of grounded ice into the ocean through buttressing. However, since the 1990s, several ice shelves have thinned, retreated, and collapsed. If this pattern continues, it could expose thick cliffs that become structurally unstable and collapse in a process called marine ice cliff instability (MICI). However, the feedbacks between calving, retreat, and other forcings are not well understood. Here we review observed modes of calving from ice shelves and marine-terminating glaciers, and their relation to environmental forces. We show that the primary driver of calving is long-term internal glaciological stress, but as ice shelves thin they may become more vulnerable to environmental forcing. This vulnerability—and the potential for MICI—comes from a combination of the distribution of preexisting flaws within the ice and regions where the stress is large enough to initiate fracture. Although significant progress has been made modeling these processes, theories must now be tested against a wide range of environmental and glaciological conditions in both modern and paleo conditions. ▪ Ice shelves, floating platforms of ice fed by ice sheets, shed mass in a near-instantaneous fashion through iceberg calving. ▪ Most ice shelves exhibit a stable cycle of calving front advance and retreat that is insensitive to small changes in environmental conditions. ▪ Some ice shelves have retreated or collapsed completely, and in the future this could expose thick cliffs that could become structurally unstable called ice cliff instability. ▪ The potential for ice shelf and ice cliff instability is controlled by the presence and evolution of flaws or fractures within the ice.Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 52 is May 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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冰架和冰崖在不断变化的气候中的稳定性

未来海平面上升的最大不确定因素是格陵兰和南极冰原的冰量减少。冰架是冰原边缘自由漂浮的冰平台，在通过承托作用限制接地冰流入海洋方面发挥着至关重要的作用。然而，自 20 世纪 90 年代以来，一些冰架已经变薄、后退和坍塌。如果这种模式继续下去，可能会暴露出厚厚的悬崖，使其结构变得不稳定，并在一个称为海洋冰崖不稳定性（MICI）的过程中坍塌。然而，人们对冰盖形成、退缩和其他作用力之间的反馈作用还不甚了解。在此，我们回顾了观测到的冰架和海洋末端冰川的碎裂模式及其与环境力量的关系。我们表明，冰架断裂的主要驱动力是长期的内部冰川压力，但随着冰架变薄，它们可能会变得更容易受到环境的影响。这种脆弱性--以及 MICI 的可能性--来自冰层内部预先存在的缺陷的分布以及应力大到足以引发断裂的区域的组合。尽管在这些过程的建模方面已经取得了重大进展，但现在必须根据现代和古生物条件下的各种环境和冰川条件对理论进行检验。冰架是由冰原喂养的浮冰平台，通过冰山崩裂以近乎瞬时的方式形成。大多数冰架表现出稳定的冰山前沿推进和后退周期，对环境条件的微小变化不敏感。一些冰架已经完全后退或坍塌，未来这可能会暴露出厚厚的悬崖，从而导致结构不稳定，即所谓的冰崖不稳定性。冰架和冰崖不稳定性的可能性受控于冰内缺陷或裂缝的存在和演变。《地球和行星科学年度评论》第 52 卷的最终在线出版日期预计为 2024 年 5 月。修订后的预计日期请参见 http://www.annualreviews.org/page/journal/pubdates。

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

Annual Review of Earth and Planetary Sciences 地学天文-地球科学综合

CiteScore

25.10

自引率

0.00%

发文量

期刊介绍： Since its establishment in 1973, the Annual Review of Earth and Planetary Sciences has been dedicated to providing comprehensive coverage of advancements in the field. This esteemed publication examines various aspects of earth and planetary sciences, encompassing climate, environment, geological hazards, planet formation, and the evolution of life. To ensure wider accessibility, the latest volume of the journal has transitioned from a gated model to open access through the Subscribe to Open program by Annual Reviews. Consequently, all articles published in this volume are now available under the Creative Commons Attribution (CC BY) license.