November 18, 2016
Barnes Ice Cap transect and closeup of divide area in August 2016. Black dots indicate summit divide of the ice cap. Notice the channels extending away from the divide. These are not stream channels, as they are too wide, but they are meltwater formed valleys that are preferred pathways for the meltwater transport.
Barnes Ice Cap located in the center of Bafﬁn Island, Canada covers an area of ~5800 km2. The ice cap is approximately 150 km long, 60 km wide and has maximum ice thickness of ~730 m and a maximum ice elevation of 1124 m above sea level (asl) at the summit of the north dome (Andrews, 2002). They also note a retreat of the southeast margin of 4 m/year from 1961-1993 on the southeast margin (Jacobs et al 1997). Dupont et al (2012) identified that the melt season increased from 66 days fro the 1979-87 period to 87 days from 2002-2010. They also noted that ICESat altimeter data indicated the thinning of the BIC at a mean rate of 0.75 m/year for the 2003–2009 period. Gilbert et al (2016) Figure 5 indicates the ELA was at 950 in the 1960-80 period and is at 1100 m from 2002-2010 this leaves a limited accumulation zone area. observe that Barnes Ice Cap has nearly lost its accumulation area over the last 10 years, in part due to the longer melt season. The glacier does tend to not retain snowcover the accumulation zone consists of superimposed ice at the crest. Papasodoro et al (2016) noted that glacier wide balances were −0.52 m w.e./year from 1960 to 2013 and doubled to −1.06m w.e./year from 2005 to 2013. They also The drainage channel development suggests meltwater transport from versus refreezing of meltwater in 2016.
Landsat comparison of the northwest margin of the Barnes Ice Cap in 1990 and 2016. Red arrows indicate terminus locations in 1990. Purple arrows indicate an area of stream development parallel to the ice front. The bright area at the margin of the ice cap is Pleistocene ice (Andrews, 2002).
Here we examined Landsat imagery from 1990-2016 to illustrate the retreat of the northwest region of the icecap and to take a look at the 2016 melt features and lack of any retained snowcover on the ice cap. In 2016 the melt channels from the divide at the crest of the ice cap are impressive. There is no retained snowcover at the summit of the ice cap even on August 9th with several week left in the melt season. The melt pathways visible in the imagery from 2016 extend 10 km downslope from the crest of the icecap. In 1990 the ice cap terminated at the red arrows, this included contact with a peninsula in Nivlalis Lake and an island in Conn Lake. By 2011 and 2014 the glacier had retreated from the locations. In 2016 the total retreat of the margin has been 600 m at Nivalis Lake, 1100 m at the island in Conn Lake and 450 m further east at the red arrow halfway to Bieler Lake. This is a slow retreat rate compared to many glaciers, but represents a much higher rate than before 1990, with rates of 18-42 m/year. There is a new section of river parallel to the ice cap margin between Conn and Bieler Laker.
2011 Landsat image of northern margin indicating retreat from the 1990 postiion red arrows.
2014 Landsat image of northern margin indicating retreat from the 1990 postiion red arrows.