greenland glacier separation – From a Glaciers Perspective

Paarliit Sermia in 2000 and 2020 Landsat images. The red arrow indicates the 2000 terminus location and the yellow arrow the 2020/21 terminus location. A denotes the junction of two main glacier branches, while B,C and D indicate tributaries

Paarliit Sermia is one of the most southerly tidewater glaciers in Greenland. It is an outlet glacier of a mountain icefield and not part of the main ice sheet. Similar to other icefield outlet glaciers whether in Alaska (Dawes Glacier) or Patagonia (Upsala) retreat is leading to glacier separation. Greenland tidewater outlet glaciers in this region have experienced substantial retreat since 1990, Weidick et al (2012) and Howat and Eddy (2011). There was also an increase in sea surface temperature (Straneo et al, 2013). Moon et al (2020) noted a there is a rapid reconfiguration of the Greenland Ice Sheet Coastal margin due to retreat. The retreat of glaciers in southern Greenland is changing the physical geography and hence the physical oceanography of the fjords. Here we examine Landsat imagery from 2000-2021 to identify the changes of Paarliit Sermia.

The Greenland Topographic map indicates the terminus down fjord from tributary B, 6.5 km from the main junction of two glacier branches at Junction A. Tributary B, C and D all feed the main glacier. By 2000 the glacier has retreated beyond tributary B and C. The snowline is between 550 m and 600 m in 2000 and 2002. In 2017 the glacier has retreated beyond Tributary D, and the snowline is slightly above 600 m. The two main branches are still joined, with the terminus now just 1 km from Junction A. Former Tributary C and D no longer reach tidewater. In 2020 the two main branches have separated and Point A is no longer a junction glacier has separated into two branches, the snowline is at ~600 m. In mid-June of 2021, the snowline is already at 500 m, despite being early in summer. Paarliit Sermia has retreated 2.4 km from 2000-2021, a rate of ~200 m/year.

Nearby Kangersuneq Quingordleq Glacier retreated 2.8 km from 1999-2016. To the northeast Qaleraliq has experienced a 3.2 km retreat of its west arm and 1.2 km of its east arm from 1992 to 2012. To the northeast Tingmiarmiit Glacier’s retreat from 1999-2015 has led to complete separation of the western and northern tributary. The western tributary is the main glacier and has retreated 2.4 km and the northern tributary has retreated 2.2 km in the 16 year period. In the case of nearby Tasermiut Fjord retreat has led to the fjord losing its tidewater connection.

Paarliit Sermia in 2002 and 2017 Landsat images. The red arrow indicates the 2000 terminus location and the yellow arrow the 2020/21 terminus location. A denotes the junction of two main glacier branches, while B,C and D indicate tributaries

Paarliit Sermia in 1980’s Greenland Topographic map (from Nuna GIS) and 2021 Landsat images. In the Landsat image the red arrow indicates the 2000 terminus location and the yellow arrow the 2020/21 terminus location. On both map and image A denotes the junction of two main glacier branches, while B,C and D indicate tributaries

Tingmiarmit Glacier comparison in 1999 and 2015 Landsat images indicating the separation of tributaries at the terminus. The red arrows indicate the 1999 terminus and the yellow arrows the 2015 terminus location. Point A is peninsula where the tributaries joined, and Point B is a nunatak just upglacier from the 2015 terminus.

Tingmiarmit Glacier (Timmiarmiit also) ends in the Tingmiarmit Kangertivat Fjord in southeast Greenland. The glacier is just south of Heimdal Glacier and is noted by Rignot et al (2012) as having a velocity of 1.4 to 3 km/year. Moon et al (2012) note that most glaciers in SE Greenland experienced a significant velocity increase after 2000. In 1999 the glacier terminus was beyond the junction of two main tributaries, with little variation from 1994. Here we examine 1999-2015 imagery to identify the separation and retreat. The retreat is similar to that of nearby Thrym Glacier, which also had a tributary separation and nearby Puisortoq.

In 1999 the glacier terminates 1 km beyond the junction of the two tributaries, indicated by red arrow on each image. The fjord is 2.2 km wide at this point. The terminus had not changed in 2001 Landsat imagery. By 2010 terminus is now located at the junction of the two glaciers. which still share a single calving front, though the calving front is longer with northern and western facing section. In 2015 retreat has led to complete separation of the western and northern tributary. The western tributary is the main glacier and has retreated 2.4 km and the northern tributary has retreated 2.2 km in the sixteen year period. The retreat of the northern tributary has been slower since 2010. The western tributary now terminates 1.5 km from former junction.The fjord is expanding in width, which suggests the current terminus is not at a stable location. The nunatak marked B is a potential point of stability but not likely as the main arm of the glacier goes south of this location and then the fjord continues to expand. Moon and Joughin (2008) observed an ice sheet tidewater glacier retreat rate increase from 2000-2006, coinciding with an increase here. Howat and Eddy (2010) noted a mean change for this region of -107 m per year. Tingmiarmit Glacier’s rate of retreat was slightly higher at 120 m/year for the 1999-2010 period and . Polar Portal continues to expand the number of glaciers with updated terminus positions from satellite imagery with 20 presently.

Mountain Photographer Jack Brauer captured an excellent image of the terminus area in late August, particularly given it was out a commercial airliner window. This image illustrates the steeper slopes and much smaller contribution of the tributaries to the right (east) of Point A and B. The image also indicates that Point B is likely not a significant pinning point to stabilize the terminus. The map below from the Greenland Geological Data viewer indicates the change with the tributaries now disconnected.