Kerguelen Island Glacier Retreat Expands Lake District

Eastern Outlet glaciers of Cook Ice Cap in a 2001 Landsat and 2019 Sentinel image indicating retreat from 2001 terminus positions (red arrows) to 2019 terminus location (yellow arrows) (Source: Mauri Pelto).

The east side of the Cook Ice Cap on Kerguelen Island outlet glaciers have retreated, expanding and forming a new group of lakes (Pelto, 2016). Here we examine the changes from 2001-2019, using Landsat and Sentinel imagery. Retreat of glacier in the region was examined by Berthier et al (2009) and is exemplified by the retreat of Ampere Glacier.  Verfaillie et al (2016) examined the surface mass balance using MODIS data, field data, and models.  The accelerating glacier wastage on Kerguelen Island was observed do be due to reduced net accumulation and resulting rise in the transient snowline since the 1970s, when a significant warming began.  This has led to nunatak expansion on the ice cap.

In 2001, the northern outlet glacier terminates in a wide portion of the proglacial lake #1.  The central outlet, #2, has two terminus locations the northern is in a proglacial lake that is kilometers long and the southern arm terminates on land.  The southern outlet terminates on land.  By 2011, the northern outlet has retreated into a narrow section of the proglacial lake. The center terminus has retreated with a new lake forming in front of its southern arm. The southern outlet has retreated revealing a new developing lake.  In 2014, the northern terminus has retreated from the primary proglacial lake. The central terminus is producing icebergs from both arms. The lake continues to expand at the southern outlet. The 2019 image is from early in the melt season. The northern terminus has retreated 1100m since 2001, and is no longer calving in a substantial lake. The central terminus has retreated with the northern and southern arm retreated 1500-1800m, with a new lake forming in front of the southern arm.  The southern outlet glacier has retreated the most, 2100m since 2001, leading to the formation of a new lake of the same length. Outlet glaciers of the ice cap that are not calving are also retreating indicating that the retreat has been driven by rising snowline and enhanced by calving. The central and southern outlets continue to calve and should continue retreat more rapidly than the northern outlet.

Eastern Outlet glaciers of Cook Ice Cap in a 2001 Landsat and 2019 Sentinel image indicating retreat from 2001 terminus positions (red arrows) to 2019 terminus location (yellow arrows) (Source: Mauri Pelto).
Digital Globe image of the Cook Ice Cap, with the main outlet, Ampere Glacier and the three glaciers examined here 1-3 (Source: Mauri Pelto).

This story originally appeared on the AGU blog From a Glaciers Perspective.