Abstract

The contribution of Antarctica’s ice sheet to global sea-level rise depends on the very dynamic behavior of glaciers and ice shelves. One important parameter of ice-sheet dynamics is the location of glacier and ice-shelf fronts. Numerous remote sensing studies on Antarctic glacier and ice-shelf front positions exist, but no long-term record on circum-Antarctic front dynamics has been established so far. The article outlines the potential of remote sensing to map, extract, and measure calving front dynamics. Furthermore, this review provides an overview of the spatial and temporal availability of Antarctic calving front observations for the first time. Single measurements are compiled to a circum-Antarctic record of glacier and ice shelf retreat/advance. We find sufficient frontal records for the Antarctic Peninsula and Victoria Land, whereas on the West Antarctic Ice Sheet (WAIS), measurements only concentrate on specific glaciers and ice sheets. Frontal records for the East Antarctic Ice Sheet exist since the 1970s. Studies agree on the general retreat of calving fronts along the Antarctic Peninsula. East Antarctic calving fronts also showed retreating tendencies between 1970s until the early 1990s, but have advanced since the 2000s. Exceptions of this general trend are Victoria Land, Wilkes Land, and the northernmost Dronning Maud Land. For the WAIS, no clear trend in long-term front fluctuations could be identified, as observations of different studies vary in space and time, and fronts highly fluctuate. For further calving front analysis, regular mapping intervals as well as glacier morphology should be included. We propose to exploit current and future developments in Earth observations to create frequent standardized measurements for circum-Antarctic assessments of glacier and ice-shelf front dynamics in regard to ice-sheet mass balance and climate forcing.

Highlights

  • Relevance of Antarctica and Scope of this ReviewAntarctica is a continent of superlatives

  • This review provides a comprehensive overview of ice shelf and glacier front measurements along the Antarctic coastline

  • A uniform circum-Antarctic record on calving front locations will allow a better linkage between changes in boundary conditions and glacier and ice shelf retreat

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Summary

Introduction

Relevance of Antarctica and Scope of this Review. The Antarctic ice sheet stores about 91% [1] of the global glacier ice on an area of 13.9 × 103 km2 [2]. If the Antarctic ice sheet melted completely, this mass loss would raise our global sea level by 58.3 m [3]. Between 1992–2017, the annual mass loss of the Antarctic ice sheet was −109 Gt/yr ± 56, which was equal to a rise of 0.3 mm/yr in sea level [4]. The Antarctic coastline has a length of about 43,449 km [5], which is longer than the circumference of the Earth, with 75% of the coastline being ice shelves, which cover an area of 1.56 × 106 km2 [6]. Innumerable smaller glaciers are located along the Antarctic coast. The total number of Antarctic glaciers is unknown, but rough estimates range from 2752 [7] to 3274 glaciers [3]

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