Dexterity Ice Cap, Baffin Island

At the south end of Dexterity Fjord on the northeast coast of Baffin Island is an unnamed icecap that I will refer to as Dexterity Icecap. Gardner et al (2012). Gardner et al 2011 and Sharp et al (2011) both note that the first decade of the 21st century had the warmest temperatures of the last 50 years, the period of record. identified that the mass loss had doubled in the last decade versus the previous four for Baffin Island. dexterity geLandsat images from 1990, 1994 and 2011 are used to assess the changes in this icecap. Red arrows are used to identify nunataks within the icecep, bedrock islands amidst the glacier. In 1990 and 1994 there are three evident nunataks. By 2011 there are six nunataks indicating this ice cap is thinning. In 2011 the ice cap has only 5-10% snowcover, the rest has melted away, not a good sign for an ice cap. There are a series of letters A-F on each image indicating particular locations. It is evident that the terminus has shrunk in width in particular in 2011 from the 1990’s. At Point B the glacier has receded from the edge of a small lake. At Point C a small ice cap has separated from its larger neighbor between the 1990’s and 2011. At Point D it is difficult to discern the terminus in the lake in 1990 and 1994. That the lake is open in 2011 and has numerous icebergs and the open water can absorb more heat from the sun, suggests that this terminus could suffer from enhanced melting and calving going forward. Point E represents a small tongue of ice that in the 1990’s extended to the top of gully, but by 2011 was gone. Point F indicates an ice cap that has a very tenuous connection to the Dexterity Ice Cap. It is the width of the ice cap that has diminished the most from 800-900 meters in the 1990’s to 500-600 m in 2011. The retreat of Dexterity Ice Cap is similar to that of Penny Ice Cap further south on Baffin Island and Devon Ice Cap further north in the Canadian Arctic. A paper out this past week concludes that there is an ongoing irreversible mass loss of glaciers in the Canadian Arctic Lenearts et al (2013).

dexterity icecap 1990

dexterity icecap 1994

dexterity icecap 2011

Penny Ice Cap southwestern margin retreat

Examination of 1991 and 2009 Landsat imagery highlights the retreat of the Penny Ice Cap at its southwestern margin. The glaciers and lakes in this region are unnamed. The Penny Ice Cap is one of two large ice caps on Baffin Island and is the southernmost of the two, with an area of more than 5600 square kilometers. On the east side the glacier exit the ice cap through spectacular mountains. The westside spreads across rolling upland terrain. In this post we examine the margin at the southwest corner, where the ice cap ends in a series of upland lakes. Changes in the margin are identifed from Landsat images from 1991-top, 2003-middle and 2009-bottom. The snowline in this region is near 900 meters in the 1991 and 2003 images. In the 2009 image the snowline is at least 1100 meters leaving the southwest corner of the Penny Ice Cap with a minimal accumulation zone. Zdanowizc et al (2012) note that in recent years the ice cap has experienced heightened melt and that little retained snowpack survives the summer, that most of the retained accumulation is refrozen meltwater (superimposed ice). In each image key locations are indicated: the nunataks are marked with violet arrows as is the margin downstream of the nunataks, key islands and peninsulas are noted with green arrows that are at the 1991 margin, the orange arrow indicates a region just east of a key marker lake. Landsat imagery from 2003 and 2009 indicates the same locations. It is evident that new islands, lakes and peninsulas are developing. The retreat and formation of new lakes at the orange and violet marginal arrow are apparent the appearance of new islands in the lakes at the green arrows is also evident. One of the largest marginal changes is downstream of the nunataks. In 1991 the margin here had no notable indent from the rest of the margin and the glacier surface was not notably debris covered. In 2009 the margin has developed a new lake as an indent has formed and the glacier surface has more evident debris. This debris is too thin to insulate the ice underneath and instead will reduce the albedo and enhance melting. The nunatak is also expanding particularly toward the margin. Overlaying the 1991 and 2009 images in Google earth provides comparison of the margin of 1991 to the Google Earth imagery and 2009 imagery. The retreat along this section of the ice cap is 300-400 meters during this 18 year period. The driving force has been an increase in temperature and this has caused mass losses on ice caps throughout the Canadian Arctic (Gardner, et al. 2011) and (Sharp et al, 2011). The mass losses of the Penny Ice Cap are also affecting the eastern margin around Coronation Glacier.

Penny Ice Cap Retreat, Baffin Island

The Penny Ice Cap is extends north from the Pangnirtung Pass regiion of Baffin Island.. To capture the majesty of the region, you have to turn to the artwork of Cory Trepanier, seen below is his Great Glacier study, not to the science data. The ice cap has been shrinking as evidenced by the retreat of a number of outlet glaciers. This post focuses on two of these glaciers. The first is Turner Glacier which flows 11 km downvalley from the ice cap ending in the Pangnirtung Valley. In 1961Turner Glacier reached to the summit lake in Pangnirtung Pass. In 1953 the glacier front was also much wider as seen in an Arctic Institute of North America Photograph. In the images below Turner Glacier enters from the left center of the image. By 2004 (top image) the glacier had receded 280 meters from the lake shore and 600 meters from the moraine it was in contact with in 1953. By 2009 the retreat was 570 meters from the lake shore and 900 meters from the moraine, bottom image. The 2009 image is an August 2009 Landsat Image. . In particular retreat after 2000 has been more rapid. Coronation Glacier is the largest outlet glacier of the Penny Ice Cap, it extends 35 km from the edge of the ice cap terminating in Coronation Fjord. Syvitski (1992) noted that Coronation glacier has been retreated at an average rate of 12 meters per year from 1890-1988Coronation Glacier. The focus at Coronation Glacier (C) is the imagery from 2004 and 2009 both indicating a lack of snow cover on some of the small glaciers adjacent to this glacier. Glaciers A and B are nearly snow free in both summers, and this is still in August. The small glacier labelled D is snow free in 2009. . In this five year interval The Coronation Glacier has retreated 200 m. Note the change in the glacier terminus position with respect to the stream entering the north side of the fjord at the terminus. The limited snow cover on Baffin Island mirrors that of most of the Canadian Arctic in recent years with high melt rates leading to mass balance losses and sea level rise as published this week by Gardner and others (2011).