Preprints
https://doi.org/10.5194/tc-2020-376
https://doi.org/10.5194/tc-2020-376

  25 Jan 2021

25 Jan 2021

Review status: this preprint is currently under review for the journal TC.

High-resolution inventory to capture glacier disintegration in the Austrian Silvretta

Andrea Fischer, Bernd Seiser, Kay Helfricht, and Martin Stocker-Waldhuber Andrea Fischer et al.
  • Institute for Interdisciplinary Mountain Research, Austrian Academy of Sciences, Innsbruck, Austria

Abstract. Eastern Alpine glaciers have been receding since the LIA maximum, but the majority of glacier margins could be delineated unambiguously for the last Austrian glacier inventories. Even debris-covered termini, changes in slope, colour or the position of englacial streams enabled at least an in situ survey of glacier outlines. Today the outlines of totally debris-covered glacier ice are fuzzy and raise the theoretical discussion if these glaciogenic features are still glaciers and should be part of the respective inventory – or part of an inventory of transient cryogenic landforms. A new high-resolution glacier inventory (area and surface elevation) was compiled for the years 2017 and 2018 to quantify glacier changes for the Austrian Silvretta region in full. Glacier outlines were mapped manually, based on orthophotos and elevation models and patterns of volume change of 1 to 0.5 m spatial resolution. The vertical accuracy of the DEMs generated from 6 to 8 LiDAR points per m2 is in the order of centimetres. calculated in relation to the previous inventories dating from 2004/2006 (LiDAR), 2002, 1969 (photogrammetry) and to the Little Ice Age maximum extent (moraines). Between 2004/06 and 2017/2018, the 46 glaciers of the Austrian Silvretta lost −29 ± 4 % of their area and now cover 13.1 ± 0.4 km2. This is only 32 ± 2 % of their LIA extent of 40.9 ± 4.1 km2. The area change rate increased from −0.6 %/year (1969–2002) to −2.4 %/year (2004/06–2017/18). The annual geodetic mass balance showed a loss increasing from −0.2 ± 0.1 m w.e./year (1969–2002) to –0.8 m ±0.1 w.e./year (2004/06–2017/18) with an interim peak in 2002–2004/06 at −1.5 ± 0.7 m w.e./year. Identifying the glacier outlines offers a wide range of possible interpretations of former glaciers that have evolved into small and now totally debris-covered cryogenic geomorphological structures. Only the patterns and amounts of volume changes allow us to estimate the area of the buried glacier remnants. To keep track of the buried ice and its fate, and to distinguish increasing debris cover from ice loss, we recommend inventory repeat frequencies of three to five years and surface elevation data with a spatial resolution of one metre.

Andrea Fischer et al.

Status: open (extended)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2020-376', Anonymous Referee #1, 21 Feb 2021 reply
    • AC1: 'Reply on RC1', Andrea Fischer, 29 Mar 2021 reply
  • RC2: 'Comment on tc-2020-376', Anonymous Referee #2, 22 Mar 2021 reply
    • AC2: 'Reply on RC2', Andrea Fischer, 01 Apr 2021 reply

Andrea Fischer et al.

Andrea Fischer et al.

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Short summary
Eastern Alpine glaciers have been receding since the LIA maximum, but the majority of glacier margins could be delineated unambiguously. Today the outlines of totally debris-covered glacier ice are fuzzy and raise the discussion if these features are still glaciers. We investigated the fate of glacier remnants with high resolution elevation models, analyzing also thickness changes of buried ice. In the past 13 years, the 46 glaciers of Silvretta lost 1/3 of its area.