Penny ice cap rising snowline – From a Glaciers Perspective

This is a portion of the island emerging from beneath the terminus with the 20-50 m high ice front in July 2023, the main portion of the island extends to the left and then out from the glacier. (Bischke/Biner/Bessen/Klemmensen)

Coronation Glacier is the largest outlet glacier of the Penny Ice Cap on Baffin Island. The glacier has an area of ~660 square kilometers and extends 35 km from the edge of the ice cap terminating in Coronation Fjord. Retreat from 1989 to 2023 has been 1050 m on the northern side of the fjord and 900 m on the south side of the fjord. The average retreat of 975 m in 33 years is ~30 m/year, much faster than the 1880-1988 period. Locations 1-9 are tributaries that have each narrowed or retreated from the main stem of the glacier. I reported on a new island forming at the terminus in 2016, and I have been hoping to identify someone who would visit the island. The island now has an area of 0.25 km², its character is evident in images below. Amanda Bischke reached out on behalf of a four person climbing team heading into the area this summer. In mid-July the team had reached the front of the glaciers and over the next 20 days explored the glacier and its tributary. Here I analyse images taken by the team of Amanda Bischke, Shira Biner, Noah Bessen and James Klemmensen in conjunction with Sentinel images. One striking aspect of the Sentinel image from August 16, 2023 is how the snowline is on the ice cap feeding tributary 1-3 at 1500 m. This has become a common theme, and is resulting in less flow from the ice cap down these tributaries leading to detachment. Tributary 1, 3 and 6 have separated from the main glacier, while Tributary 2,4,7 and 9 have detachments nearly or completely severing the glacier enroute to the main glacier.

I appreciate the collaboration with the climbing party who have posted an initial report, I will update when further reports are published. Of their four first ascents, The Drawbridge was a visually compelling line to me. If you are heading out into a seldom visited glaciated area on a climbing expedtion reach out and see what would be valuable to observe. We can see overall changes from satellite imagery, but not the details. Two examples here are what the surface of the island is composed of, sand and small rocks in this case, or a developing detachment such as at the chasm are not evident from satellite imagery.

As the glacier retreats the Island continues to expand from 2017-2023. The tributaries I hoped the climbing team could document where possible if they were still attached.

The climbing team visiting the oldest part of the island looking toward newest part (Bischke/Biner/Bessen/Klemmensen)

A view of the island from the north side of Coronation Glacier (Bischke/Biner/Bessen/Klemmensen)

Sentinel image of the expanding island at the Coronation Glacier terminus in Sentinel images.

Tributary 1 detached from main glacier, note high snowline (Bischke/Biner/Bessen/Klemmensen)

Tributary 2 has a detachment point before the main glacier, though relict ice below still connects. Note snow is only retained at very top of ice cap with a month of melt season left. (Bischke/Biner/Bessen/Klemmensen)

Tributary 6 is still connected all the a detachment is occurring halfway from ice cap to main glacier. (Bischke/Biner/Bessen/Klemmensen)

Tributary 7 and 8 are still connected, though 7 has a detachment now (Bischke/Biner/Bessen/Klemmensen)

Triburary 9 had an interesting barrier to the climbers a deep chasm carved by an outlet stream draining meltwater, some of which had pooled in the lake shown. (Bischke/Biner/Bessen/Klemmensen)

Penny Ice Cap Northern Outlet Glacier #43 in 1989 and 2016 Landsat images. Red arrow indicates 1989 terminus, yellow arrow 2016 terminus. Two peripheral ice masses are at Point A and B.

The primary northern outlet from the Penny ice Cap is an unnamed glacier, noted as #43 in the recent study by Van Wychen et al (2015). it is one of two large tidewater outlet glaciers on Baffin Island. Here we examine the response driven by climate change of this glacier from 1989 to 2016 using Landsat and Sentinel Imagery. Van Wychen et al (2015) observe that it is one of the two largest discharging glacier on the island and the Penny Ice Cap, with Coronation Glacier. They observed peak velocities of over 100 m/year, 20 km upglacier of the terminus, declining to less than 20 m/year in the lower 10 km of the glacier. Zdanowizc et al (2012) noted that in recent years the ice cap has experienced heightened melt, a longer melt season and that little retained snowpack survives the summer, that most of the retained accumulation is refrozen meltwater or superimposed ice. Geodetic methods indicate surface lowering of up to 1 m/year on all ice masses on Baffin Island and Bylot Island between 1963 and 2006 (Gardner et al.2012).

In 1989 the glacier terminated 1 km south of a terminal moraine peninsula that extends most of the way across the fjord. By 2014 glacier retreat is accompanied by the formation of two deltaics areas in front of the glacier, orange arrows in images below. It is not clear if these are islands, a shoal in the fjord or the head of the fjord. Retreat from 1989 to 2016 is 900 m on the west side of the terminus, 600 m on the east side. Two peripheral ice masses at Point A and B lack snowcover in 2016 and have lost area as well. Extensive transverse crevasses develop in the last 700 m upglacier of the terminus, indicating the force imbalance that enables and enhances calving at the ice front, yellow arrow. The reduced retained snowpack on the Penny Ice Cap is leading to reduced discharge and glacier retreat. With a high snowline in 2016 indicated by the lack of retained snowpack on ice masses at Point A and B, it is clear this trend is ongoing. The impact is less dramatic than those noted in the Clephane Bay area of Baffin Island.

Penny Ice Cap Northern Outlet Glacier in 2016 Sentinel 2 image. Yellow arrow indicates crevassing triggered by calving processes, orange arrows developing deltaics areas.

A 2014 Google Earth image of glacier front. Red arrow indicates 1989 terminus, yellow arrow 2016 terminus and orange arrows deltaic land areas building.