Long Peak Glacier, Southeast Alaska

“Long Peak” Glacier is an unnamed glacier southeast of Juneau, Alaska. The glacier occupies a narrow northeast oriented avalanche fed valley, light blue arrows indicate the avalanche feeding regions around the glacier. In 1948, as indicated in the USGS map,the glacier extended from 1600 m to 500 m, a small lake is shown at the terminus, with an overall length of 3.8 km. The glacier is a short distance southwest of the retreating Speel Glacier, and it does drain into the Speel River. Here we examine Landsat imagery of changes in this glacier from 1984 to 2013. This is a small, remote glacier that receives that has not attracted attention. It is close to the Long Lake Snotel snowpack measurement station operated by the USDA. I observed the glacier in 1998 from a helicopter and thought it did not look poised to survive our warming climate for long. long peak glacier
Here we examine Landsat imagery from 1984-2013 to observe glacier retreat and lake expansion. By 1984 the lake had expanded to 750 m in length, with a glacier retreat of 500 m from the mapped terminus. The snowline is marked with purple dots, the 2013 terminus with a red arrow, and the orange arrow indicates a debris covered region of the glacier. Only 20% of the glacier is snowcovered and the melt season is not yet over in the 1984 image. This same pattern of snowcover remaining is seen in 1993, 1995, 1996, 1997 and 1998 for example. By 1999 the glacier has retreated an additional 300-350 m, the snowcovered area is greater but this is an August image. In 2013 a late June and a Late July image depict the loss of snowcover during a month. The overall length of the glacier is now 2.6 km, indicating a retreat of 1200 m since and a retreat of 700 m from 1984-2013. The glacier is still terminating in the lake that has expanded by the same amount. This glacier has not only retreated but also thinned and the slopes above the glacier have greened a bit particularly on the north side. This glacier cannot survive with the level of retained snowcover it has (Pelto, 2010). Ongoing mass balance work on the Lemon Creek Glacier of the Juneau Icefield, where the Juneau Icefield Research Program is beginning measurements next week, has thinned by 29 m during the 1955-2013 period (Pelto et al, 2013). In 2014 the Long Lake Snotel site at an elevation of 850 feet, lost its snowpack on June 11, a bit earlier than normal, indicating this glacier will lose most of its snowpack in 2014.

long peak 1984
1984 Landsat image

long peak 1997
1997 Landsat image

long peak 1999
1999 Landsat image

long peak june 2013June 2013 Landsat image

long peak 2013
July 2013 Landsat image


Sacagawea Glacier, Wyoming is Disappearing

Sacagawea Glacier in the Wind River Range of Wyoming lost 35% of its area between 1966 and 2006. This glacier on the west slope of Sacagawea Peak and Helen Peak and just north of Upper Fremont Glacier. Here we compare Google Earth imagery of the glacier that indicates the change during this forty year period. In 1966 the glacier had an area of square kilometers. The first image is the USGS map of the glacier from 1966 imagery. The orange outline is the glacier margin at this time and the red outline the 2006 glacier boundary. By 1994 Google Earth images indicate a retreat of 270 m along its main terminus. A small lake has also begun to form along the southern section of the terminus. The northern section of the glacier below Helen Peak had by 1994 become practically disconnected from the main section of the glacier. In 1994 the exposed blue ice area is extensive, indicating that most of the glacier was consistently losing its snowcover. With retained snowcover limited to the steeper slopes above 3700 m. By 2006 the lake was 400 m long and 150 wide along the southern section of the terminus. The terminus retreat along the main terminus averaged 350 m since 1966. The northern section of the glacier is fully detached from the rest of the glacier. The fraction of snowcovered area is 10% in 2006, which was typical for the 2003-2006 period. This is insufficient to maintain a glacier, the snowcovered area for temperate alpine glaciers such as the Sacagawea that lacks extensive avalanching is 55-65 % snowcover at the end of the melt season. The locations marked with Point A in red are locations where rock formerly beneath the glacier has been exposed as the glacier melted from that location. By 2013 a Landsat image of the glacier indicates that the glacier is beginning to recede from the terminus lake, further that there is almost no retained snowcover in 2013 and that the glacier is separated into three segments note the yellow arrows. The upper margin of the glacier is receding which indicates thinning in the accumulation zone, an indicator that this glacier does not have a significant accumulation zone and cannot survive current climate (Pelto, 2010). In a Planet Action Project Pelto (2010)reported that 2/3 of the 15 Wind River glaciers examined were not going to survive current climate. This includes Minor Glacier, Sourdough Glacier, Grasshopper Glacier and Lower Fremont Glacier.sacagawea comparison
1966 USGS map

Sacagawea Glacier 1994
1994 Google Earth

sacajawea 2006
2006 Google Earth

sacagawea 2013
2013 Landsat Image

Analysis of Sacagawea Glacier and Upper Fremont Glacier, Wind River Range, Wyoming

Kirtisho Glacier Retreat, Georgia

The southern flank of the Caucasus Mountains is in the nation of Georgia. Ten kilometers southwest of the Lednik Karaugom Glacier, Russia from the previous post is Kirtisho Glacier a 4.5 km long valley glacier, a small subglacier KS is also examined in this post.caucasus submap The glaciers in the Causcasus Mountains have been undergoing a significant retreat, the USGS, (2010) Satellite Image Atlas of Asia, noted that nearly all of the 65 glaciers examined in this region experienced significant retreat from 1987-2004. Shahgedanova et al, (2009) noted a 8 meters per year average retreat rate for the 1985-2000 period. To get a feel for the terrain watch the trailer for the On the Trails of the Glaciers- Caucasus 2011. The video does not show Kirtisho Glacier but does indicate the nature of the terrain. This is a project of an Italian group Macromicro, that had contacted me about an upcoming expedition to Alaska in 2013. Landsat images from 1986 (second image) and 2012 (third image) along with 2011 Google Earth imagery (top and bottom image) are shown below. Kirtisho Glacier has a top elevation of 3700 meters and a terminus that in 2012 is at 2600 meters, and was 2400 m in 1986. The snowline has typically been at 3300 meters, blue arrow, which is too high to sustain the terminus at 2600 m. The terminus position in 1986 is indicated by a red and yellow arrow that are also used in the 2012 imagery and the 2011 terminus closeup. The magenta arrow in the Landsat images indicates the beginning of a separation from an northern tributary, which is close to the snowline. The terminus itself is not crevassed in the lowest 400 meters, suggesting retreat will continue for this nearly stagnant section. KS the small glacier to the south, has decreased in area from 0.45 km2 in 1986 to 0.20 km2 in 2012. We also examine this more below. kirtisho glacier profile

kirtisho 1986Kirtisho 2012

kirtisho terminus The KS glacier viewed up close is quite thin, with limited crevasses. The red arrows indicate rock protruding through this glacier in many locations. These rocks indicate how thin the ice is, and will help absorb heat and hasten melting as the rock outcrops expand. In 2011 and in the 2012 imagery there is no remaining snow on the glacier. A glacier without a persistent accumulation zone cannot survive (Pelto, 2010). KS glacier will not survive much longer. ks 2011