October 1, 2015

Palma Glacier, Alaska Retreat Opens Lake Passage

Posted by Mauri Pelto

Palma Compare
An August 1986 and September 2015 Landsat Image of Palma Glacier, 1986 terminus yellow arrow.
Palma Glacier is an unnamed glacier just west of Brady Glacier and Glacier Bay that is the principal glacier draining into Palma Bay.  Here we examined the changes in this glacier from 1986 to 2015 with Landsat Imagery.  The glacier has terminated in a lake at the head of a river draining into Palma Bay at least since the 1950 USGS map was prepared.The neighboring Brady Glacier advanced for much of the 20th century,  its tributary lobes began to retreat after 1970.  The main Brady Glacier terminus did not begin to retreat until 2009 and is poised to begin a rapid retreat as lake development at the terminus continues due to ongoing thinning (Pelto et al, 2013)..

palma glacier ge

Google Earth image of the Palma Bay and Palma Glacier region

In 1986 Palma glacier flowed south out of the mountains before turning sharply west for 2 km before terminating in a lake at the yellow arrow. The lake had considerable debris covered ice bergs that had recently calved. By 1999 the glacier had retreated to the westward turn, red arrow, but did extend to the south side of the lake.  By 2014 the glacier had retreated from the westward turn, red arrow, and the strip of land between the two lakes at the purple arrow has been exposed and vegetated. it is now possible to paddle up one lake and portage to the next. The snowline purple dots is at 1000 m.  In 2015 this September image at top is after an early season snowfall, the last image below is an August image indicating the snowline is again at 1000 m with several weeks left in the melt season.  The glacier has retreated 2100 meters from 1986 to 2015 and still terminates in the lake. The retreat has slowed since 1999 after the lake narrowed at the westward turn. Retreat will continue as a snowline at 1000 m is to high to sustain even the current size of Palma Glacier.

palma Glacier1986
1986 Landsat image

palma glacier1999
1999 Landsat Image
palma glacier 2014
2014 Landsat Image
Palma snowline Aug 2015
2015 Landsat Image