Driving Forces of Circum-Antarctic Glacier and Ice Shelf Front Retreat over the Last Two Decades

• Main Authors: Baumhoer, Celia A., Dietz, Andreas J., Kneisel, Christof, Paeth, Heiko, Kuenzer, Claudia
• Format: Text
• Language: English
• Published: 2020
• Subjects: Antarctic; Antarctic Peninsula; The Antarctic; West Antarctica; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Ice Shelves; Sea ice
• Online Access: https://doi.org/10.5194/tc-2020-224; https://tc.copernicus.org/preprints/tc-2020-224/

The safety band of Antarctica consisting of floating glacier tongues and ice shelves buttresses ice discharge of the Antarctic Ice Sheet. Recent disintegration events of ice shelves and glacier retreat indicate a weakening of this important safety band. Predicting calving front retreat is a real challenge due to complex ice dynamics in a data-scarce environment being unique for each ice shelf and glacier. We explore to what extent easy to access remote sensing and modelling data can help to define environmental conditions leading to calving front retreat. For the first time, we present a circum-Antarctic record of glacier and ice shelf front retreat over the last two decades in combination with environmental variables such as air temperature, sea ice days, snowmelt, sea surface temperature and wind direction. We find that the Antarctic ice sheet area shrank 29,618 ± 29 km 2 in extent between 1997–2008 and gained an area of 7,108 ± 144.4 km 2 between 2009 and 2018. Retreat concentrated along the Antarctic Peninsula and West Antarctica including the biggest ice shelves Ross and Ronne. Glacier and ice shelf retreat comes along with one or several changes in environmental variables. Decreasing sea ice days, intense snow melt, weakening easterlies and relative changes in sea surface temperature were identified as enabling factors for retreat. In contrast, relative increases in air temperature did not correlate with calving front retreat. To better understand drivers of glacier and ice shelf retreat it is of high importance to analyse the magnitude of basal melt through the intrusion of warm Circumpolar Deep Water (CDW) driven by strengthening westerlies and to further assess surface hydrology processes such as meltwater ponding, runoff and lake drainage.