December 7, 2014
Sinclair Mountain is on the east side of the Lynn Canal in southeast Alaska. The mountains hosts too substantial glacier, the south flowing unnamed glacier is referred to here as Sinclair Glacier. This glacier terminated in a lake in the 1982 map of the Skagway region. I observed this glacier from the air in 1982 and it was ending in this lake. Here we examine Landsat imagery from 1984 to 2014 to identify changes.
USGS Skagway map
Google Earth Image
In 1984 the glacier ended at a prominent peninsula in the lake, red arrow in each image, the lake was 1700 m long. The snowline was at 950 m, indicated by the purple arrow, this was at the end of the melt season. The glacier was joined by two tributaries from the west side, orange arrows. In 1986 there is a small amount of terminus retreat visible. By 2001 the glacier has retreated out of the lake, which is 2.9 km long. By 2004 the southern tributary at the orange arrow is no longer connected to the glacier. The glacier has retreated 1.3 km from 1984-2004. The snowline is at 950 m with a month left in the melt season. In 2009 the image is not great quality, but the northern tributary is still connected to the main glacier by a thin tongue of ice at an icefall at 850 m. By 2013 the northern tributary is no longer connected to the main glacier, there is bare rock extending across the full width of the former icefall area. In 2014 the image is from the end of July and the snowline is already above 950 m. It is evident that the glacier will lose nearly all of its snowcover by the end of the melt season on October 10th. The glacier has retreated 900 meters since 2004, and 2.2 km since 1984. The recent loss of tributaries indicates less contribution of ice to the glacier and that retreat will continue. This retreat is the same as that of nearby Field Glacier, Meade Glacier and Ferebee Glacier.