Tag: Featured

Lucia Glacier, Chile Retreat Opens New Embayment

On By mspeltoIn chile glacier melt, chile glacier retreat

Lucia Glacier retreat from 1987 to 2016 in Landsat images.  Red arrows mark 1987 terminus, yellow arrows 2016 terminus, orange arrow an emerging bedrock area, pink arrow a tributary with increased debris cover and purple dots the snowline.

Lucia Glacier terminates in Lago Berguez at the northern margin of the Southern Patagonia Icefield.  The lake drains into the Rio Pascua.   Willis et al (2012) observed that between February 2000 and March 2012 the Southern Patagonia Icefield rapidly lost volume and that thinning extends even to high elevations.   Mouginot and Rignot (2014) illustrate that velocity peaks at 1 km/year and reamins above 500 m/year  from the terminus to the accumulation zone on Lucia Glacier. The overall retreat has been driven by increasing calving rates from the 1975-2000 to the 2000-10 period (Schaefer et al, 2015). The pattern of retreat is consistent between these glaciers and the region as noted by Davies and Glasser (2012).  They note Lucia Glacier terminus retreat rate from 1870 to 2011 was highest from 1986-2001.  Glasser et al (2016) observed both an increase in glacier proximal lakes and in debris cover on glaciers with glacier retreat from 1987-2015. In this case the glacier is now terminating in an expanding proglacial lake, and except for one western tributary that has had increased significant debris cover, the glacier has limited debris cover.

In 1987 the glacier terminated in a north south front in the lake, at red arrows.  The snowline was at 1050 m.  The western tributary at the pink arrow had 25% debris cover, while the orange arrow indicates a location covered by ice. By 1998 the glacier has retreated into a new arm of Lake Berguez and has an east west front. The snowline is at  1275 m.  The western tributary now has 55% debris cover.  In 2003 the snowline is at 1250 m and the orange arrow indicates and emerged bedrock area forming a new lateral moraine. By 2016 the glacier has retreated 3600 m on the west side and 1700 m on the east side.  The mean frontal retreat is ~2700 m in the 30 year period, 90 m/year   The snowline is at 1150 m in 2015 and 1300 m in 2016.  The western tributary is now 80% debris covered.  The terminus itself in 2003 was 1.3 km wide.  In 2016 the calving front is 1.1 km wide.  Upglacier of the current terminus the calving front will expand to 2 km in width  with a ~1.5 km  retreat.  This indicates the glacier is at a narrow point now that minimizes calving and that continued retreat will soon lead to an increase in calving.  The retreat has exposed steep unstable slopes particularly on the east side of the glacier note below and NASA image.  The retreat is greater than neighboring Gabriel Quiroz Glacier and less than Bernardo Glacier.

Lucia Glacier retreat from 1987 to 2016 in Landsat images.  Red arrows mark 1987 terminus, yellow arrows 2016 terminus, orange arrow an emerging bedrock area, and purple dots the snowline.

 

Google Earth image indicating the front of Lucia Glacier (yellow dots) and slopes destabilized by glacier retreat and thinning, pink arrows.

Gabriel Quiroz Glacier, Chile Retreat Forms New Lake

On By mspeltoIn chile glacier melt, chile glacier retreat

Gabriel Quiroz Glacier, Chile in 1987 and 2016 Landsat images illustrates the retreat.  Red arrow is 1987 terminus, yellow arrow the 2016 terminus, purple arrow a retreating northern tributary and purpe dots the snowline.

Gabriel Quiroz Glacier is a northern outlet glacier of the Southern Patagonia Icefield that drains into the Rio Pascua.  The glacier in 1987 terminated within 250 m of Lago Gabriel Quiroz.  Willis et al (2012) observed that between February 2000 and March 2012 that the Southern Patagonia Icefield is rapidly losing volume and that thinning extends even to high elevations.  The overall retreat has been driven by increasing calving rates from the 1975-2000 to the 2000-10 period (Schaefer et al, 2015). The pattern of retreat is consistent between these glaciers and the region as noted by Davies and Glasser (2012), annual rates of shrinkage in the Patagonian Andes increased in from 0.10% year from 1870-1986, 0.14% year from 1986-2001, and 0.22% year from 2001-2011, though they note Gabriel Quiroz Glacier retreat rate from 1870-2011 was low.  Glasser et al (2016) observed both an increase in glacier proximal lakes and in debris cover on glaciers with glacier retreat from 1987-2015. In this case the glacier is now terminating in a new and expanding proglacial lake, but has limited debris cover.

In 1987 the glacier terminates 250 m beyond the western shore of Lago Gabriel Quiroz there is no sign of a proglacial lake at the terminus.  The snowline is at 950 m in 1987,  A tributary from the north almost joins the main glacier, purple arrow.  In 2000 a small proglacial lake is evident at the terminus, which has retreated 300 m. The snowline is at 950 m. By 2015 a substantial proglacial lake has formed with an island in it.  The lake is 1.6 km long, which represents the retreat of the glacier since 1987. The snowline in 2015 is at 1050 m.  In 2016 the proglacial lake is filled with icebergs indicating continue calving driven terminus retreat totaling 2.1 km since 1987. The snowline in 2016 is at 950 m. The terminus remains poised for additional calving retreat, though the calving front has narrowed.  The upper limit of the lake basin is not evident.  The northern tributary has retreated up valley away from the main glacier.  This indicates that even without calving the mass balance of the glacier would be negative and there would be retreat. The retreat is similar to that seen at Balmaceda Glacier,  Bernardo Glacier and Glacier Onelli.   

Gabriel Quiroz Glacier, Chile in 2000 and 2015 Landsat images illustrates the retreat.  Red arrow is 1987 terminus, yellow arrow the 2016 terminus, purple arrow a retreating northern tributary and purpe dots the snowline.

Pedersen Glacier, Alaska Rapid Retreat 1994-2015

On By mspeltoIn alaska glacier retreat, Uncategorized7 Comments

Pedersen Glacier Kenia Peninsula, Alaska retreat from Landsat images in 1994 and 2016. The red arrow indicates 1994 terminus, yellow arrow is 2016 terminus, orange arrow indicates northern tributary and purple dots indicates snowline. 

Pedersen Glacier is an outlet glacier of the Harding Icefield in Kenai Fjords National Park near Seward, Alaska. The glacier drops quickly from the plateau of the icefield through a pair of icefalls terminating in a lake at 25 meters above sea level.  The Harding Icefield glaciers that drain east are in the Kenai Fjords National Park, which has a monitoring program.  Giffen et al (2014) observed that from 1950-2005 all 27 glaciers in the Kenai Icefield region examined retreated.  Giffen et al (2014) observed that Pedersen Glacier retreated slow but steady from 1951-1986 at 706 m (20 m/a) and 434 m (23 m/year) from 1986-2005. Here we compare a 1994, 2013, 2015 and 2016 Landsat imagery illustrating a rapid increase in retreat rate from the previous periods.

In 1994 the terminus proglacial lake at the terminus is small and much of the terminus is on land.  The snowline in 1994 is at 550 m.  The tributary entering from the north, orange arrow, is 400 m wide as it reaches Pedersen Glacier.  In 2005 the Google Earth image below indicates extensive terminus crevassing, indicating substantial terminus velocity, and that the retreat is driven by calving.  In 2005 the lake is now 1.1 km long on its center axis.  By 2015 the glacier has retreated 2600 m since 1994, a rate of 125 m/year, much faster than before.  The snowline is average 800 m.  The northern tributary is now barely reaching the main glacier and has a width of 150 m. Note there was a medial moraine separating the tributary from the main glacier in 1994 and now this is merely a lateral moraine. This tributary is not particularly impacted by calving losses and indicates a rising snowline is also a source of mass loss for the glacier. A comparison of the 2013, 2015 and 2016 terminus indicates the recession has remained rapid.  The glacier is approaching the base of an icefall that would represent the inland limit of the lake and the end of rapid retreat.  The snowline in 2013 averages 850 m and is at 800 m on Sept. 30 2016. The glacier follows the pattern of nearby Bear Glacier, Yakutat Glacier, Harris Glacier and the inital phase of retreat on Brady Glacier.

Pedersen Glacier Kenia Peninsula, Alaska retreat from Landsat images in 2013 and 2015. The red arrow indicates 1994 terminus, yellow arrow is 2015 terminus, green arrow indicates 2016 terminus and purple dots indicates snowline. 

Pedersen Glacier in 2005, note crevassing at the terminus, pink arrow. The northern tributary is indicated by orange arrow and green arrow indicates 2016 terminus position. 

Monacobreen Separates from Seligerbreen, Svalbard

On By mspeltoIn svalbard glacier retreat

Monacobreen Separation from Seligerbreen in 1999 and 2016 Landsat images.  The red arrow is the 1999 terminus location and yellow arrow the 2016 terminus location. 

Moancobreen  is a glacier that terminates at the head of Liefdefjorden , a branch of Woodfjorden in Spitsbergen, Svalbard. NW Spitsbergen is a region that has experienced extensive long term glacier thinning from 1965 to 2007 (Nuth et al, 2010). Svalbard is host to 163 tidewater glaciers with a collective calving front of 860 km (Błaszczyk et al, 2009), Monacobreen has a 4.4 km wide calving front.  The glacier has surged in the past. Oceanwide Expeditions has expeditions to the region that capture the beauty including the polar bears and ringed seals of the area. 

In 1999 Seligerbreen and Monacobreen had a joint terminus that was 6.5 km wide.  By 2013 the glaciers had separated and the tidewater terminus of Monacobreen was 4.4 km long.  Monacobreen had retreated 2200 m from 1999-2016. The snowline in 2016, see below, was at 525 m.  There are significant melt features apparent in the 2013 Google Earth image of the 500 m elevation area and melt ponds in the 1999 image. The retreat of Monacobreen  is similar to that of most tidewater glaciers in Svalbard such as,  Paierbreen, Hornbreen and Svitjodbreen.

Google Earth image of Monacobreen from 2013, indicating separation had occurred, note plume of sub glacial meltwater outflow. 

TopoSvalbard place name image of the area

Landsat image indicating melt features and snowline in 1999 and 2016 Landsat images. 

Melt water drainage features in the region from 400-550 m on Monacobreen

Mensu Glacier, Siberia Russia Retreat 1994-2016

On By mspeltoIn climate change glacier retreat, glacier climate change, Glacier Observations, russia glacier retreat

Mensu Glacier, Russia in comparison of 1994 and 2016 Landsat images.  Red arrow is the 1994 terminus, yellow arrow 2016 terminus, purple arrow a tributary and purple dots the snowline. 

Mensu Glacier (Lednik Mensu) drains northeast from Gora Belukha in the Russian Altai.  The glacier drains into the Ob River and then the Arctic Ocean.  This glacier has not been the focus of detailed research to date. Khromova et al (2014) report that at the end of the century the glacier degradation in Russian mountain ranges strengthened including glacier area loss of 13% in the Tien Shan, 19% in the Altai and 22.3% in the Polar Urals.  The icecap draining west from Gora Belukha was cored to look at longer term climate records (Fujita et al 2004).  The core at 4500 m is high enough so that significant melt events affecting the record were rare. Shahgedanova et al (2010) noted that the retreat has largely been driven by summer warming. 

In 1994 the glacier terminates at the red arrow at 2150 m.  The glacier has an icefall from 3200 m to 2700 m that generates annual ogives, note Google Earth image below. The snowline in the 1994 Landsat  image averages 3000 m.  There is a tributary joining the main glacier at the purple arrow.  A neighboring glacier terminates in a proglacial lake at the orange arrow.  By 2001 the glacier has retreated and the snowline is at 3100 m. By 2016 the glacier terminates at 2200 m and has retreated 600  m to the yellow arrow.  The tributary at the purple arrow has separated from the main glacier.  This illustrates substantial glacier thinning  6 km above the terminus. The glacier at the orange arrow  no longer reaches the proglacial lake. In August 2016 below the snowline is at 3100 m in September 2016 the snowline has descended to 2800 m.  The lowest 800 m of the glacier has few crevasses, appears stagnant and will be lost to retreat.

Retreat is similar to the nearby Potanin Glacier, Mongolia. 

Mensu Glacier, Russia in comparison of 2001 and 2016 Landsat images.  Red arrow is the 1994 terminus, yellow arrow 2016 terminus, purple arrow a tributary and purple dots the snowline. 

Google Earth image indicating the snowline at the top of the icefall and the ogives beginning at the bottom near the orange arrow.

 

Terminus of Mensu Glacier in 2013 note lack of crevassing.

Bonnet Glacier, Alberta Retreat & New Lake Formation

On By mspeltoIn alberta glacier retreat

Bonnet Glacier, Alberta compared in Landsat images from 1987 and 2016. The red arrows mark the 1987 terminus, yellow arrows are the 2016 terminus location and the orange arrow notes a separate glacier that has disappeared.

Bonnet Glacier is at the headwaters of Douglas Creek that feeds into the Red Deer River.  The glacier drains north from Bonnet Peak in the Sawback Range 30 km east of the crest of the Rocky Mountains and 40 km north of Banff.   Here we examine changes in this glacier from 1987 to 2016, a period when retreat has led to the formation of new alpine lakes. An inventory of glaciers in the Canadian Rockies indicate area loss of 15% from 1985 to 2005 (Bolch et al, 2010), with Alberta glaciers losing area at a higher rate.  Tennant et al (2012) noted that from 1919-2006 the glaciers in the central and southern Canadian Rocky Mountains lost 40% of their area.  Of the 523 glaciers they observed 17 disappeared and 124 separated. The more famous Columbia Icefield, 125km northwest, has lost 23 % of its area from 1919-2009 with ice loss at a minimum during the 1970′s (Tennant and Menounos, 2013). 

In 1987 the glacier had two primary termini, red arrows with no evident proglacial lakes at either terminus, red arrows.  In 1987 the glacier spilled over a bedrock bench shortly above the terminus in both cases onto a lower bench   The glacier has 25% retained snowpack.  The orange  arrow indicates a small avalanche fed glacier on the east side of the ridge extending north from the glacier. In 1988 the lack of proglacial lakes is noted at the pink arrows.  The retained snowpack is again 25% of the glacier area, well short of the 50-60% needed for a glacier to be in equilibrium. In 1990 the snowcovered area is 30% there is a small lake developing at the northern most terminus. In 2015 four new alpine lakes have formed two are separated from the glacier due to retreat, with both active termini also terminating in lakes. The retained snowpack covers 10% of the glacier in 2015. In 2016 snowcover is retained on 20% of the glacier. The glacier has lost 20% of its total area since 1987 with the main terminus retreating 900 m and the secondary terminus 425 m.   The 900 m retreat is ~20% of the total glacier length. The lack of retained snowcover even in these August Landsat images indicate a glacier that cannot survive current climate. The retreat is less impressive than on the larger Freshfield Glacier  and more in line with retreat and separation seen on Conway Glacier  and Fraser Glacier.

Bonnet Glacier, Alberta compared in Landsat images from 1988, 1990 and 2015. The pink arrows mark the locations where lakes developed after 1988 and the orange arrow notes a separate glacier that has disappeared.

Topographic map of the Bonnet Glacier region, Alberta.

Potanin Glacier Area, Mongolia Retreat & Fragmentation

On By mspeltoIn Mongolia glacier retreat2 Comments

Potanin Glacier, Mongolia comparsion in 1991 and 2016 Landsat images.  Yellow dots indicate 2016 terminus, purple dots the snowline, red arrow the southeast margin of proglacial lake, and purple arrows peripheral alpine glaciers that are fragmenting. 

Potanin Glacier is in the Altay Mountains of the Tavan Bogd region in western Mongolia, and is the nations longest glacier.  The glacier ranges from 2800 to 4000 m a.s.l. and is length is about 11 km long. Konya et al (2008) note the ELA was roughly estimated as 3600 m. The conclude that given the area altitude distribution this indicates the  mass balance of Potanin Glacier is negative and it is probable that the glacier is experiencing a negative trend. Konya et al (2010) observed that ablation calculated by an equation using the measured radiation showed good correlation with observed daily ablation, whereas a degree-day model had good correlation with cumulative observed ablation.  This region has experienced a substantial warming of  1.6 C in the last sixty year, which has led to a 4.2% decrease in glacier area from 1989 to 2009 in the Tovan Bogd region (Krumwiede et al, 2014). A 2016 expedition to the area led by Aaron Putnam, UMaine Climate Change Institute provides an excellent view of the region (Climate Change, Northwestern, 2016).  There expedition was focused on assessing the timing of ice loss at the end of the last ice age. This warming abruptly ended the last ice age and Putnam’s team was looking for the switches that initiate such climate events.

Here we examine Landsat imagery from 1991 to 2016 to identify changes in Potanin Glacier and neighboring glaciers. In 1991 Potanin Glacier terminates near a 500 m diameter proglacial lake, red arrow.  The snowline is at 3600 m, purple dots. Three peripheral alpine glaciers at purple arrows 1-3 are each single contiguous glaciers. In 1996 the proglacial lake remains, the snowline is at 3500 m and the peripheral alpine glaciers remain contiguous. By 2014 the proglacial lake is 30% of its former size, with the southeastern margin of the lake remains the same. The snowline is at 3500 m in 2014.  In 2016 the three neighboring alpine glaciers have fragmented into multiple sections. Each section remaining has also lost significant area.  This is indicative of negative mass balance in the region during the period.  The smaller glaciers are more responsive to climate and subsequent mass balance change.  The yellow dots on the 1991 and 2016 image represent the 2016 margin. The margin has experience modest retreat averaging 250 m from 1992-2016. At Point 1 the glacier has fragmented into three sections since 1991 with the southern most nearly gone.  At Point 2 the glacier has separated into two parts with the eastern one largely gone. The continued fragmentation of smaller glaciers will lead to their disappearance in the coming decades.  The large supraglacial streams that are present indicate the limited velocity and high melt rates in the terminus region, see below. The mass balance of the World Glacier Monitoring Service Maliy Aktru, in the Russian Altay has been negative in all but five years since 1990. 

Potanin Glacier, Mongolia comparsion in 1996 and 2014 Landsat images. Purple dots the snowline, red arrow the southeast margin of proglacial lake, and purple arrows peripheral alpine glaciers that are fragmenting.

 

Streams channels on surface of Potanin Glacier in Google Earth image. The extent and size indicates limited velocity and high ablation. 

West Ganglung Glacier, Tibet Glacier Loses 20% of Length

On By mspeltoIn china glacier retreat, Himalaya glacier retreat

Landsat image comparison from 1991, 2001 and 2016 of West Ganglung Glacier, red arrow is the 1991 terminus, yellow arrow the 2016 terminus, green arrow the eastern glacier proglacial terminus lake and purple arrow expanding zone between a former tributary and West Ganglung Glacier

West Ganglung Glacier is on the China-India border 6 km west of Ganglun Grangri Peak meltwater enters the Sultej River and then Mapam Tso.  the glacier terminates in a proglacial lake at 5200 m with its head on the border at 5750 m. This region is part of the Indus Basin, the second China glacier inventory noted a 23% decline in glacier area from 1970 to 2007 (Guo et al 2015) Assessing the sensitivity of the Sutlej River basin to climate change Miller et al (2012) noted that with a warmer climate melt contributions from lower parts are reduced because of decreased snow cover and a shorter melting season.  Significant glacier area loss will also lead to less runoff despite an increase in rate. Singh et al (2012) noted a decline in runoff from the Sutlej basin after 2000, whereas there had been a rise before that. 

Here we examine teh unnamed West Ganglung Glacier change from 1991 to 2016 in a series of Landsat images. In 1991 the glacier terminates at the red arrow, and the lake is 1050 m long. At the glacier just to the east there is a small proglacial lake 200 m long. By 2001 glacier retreat had led to lake expansion to 1400 m long. The proglacial lake at the end of the eastern glacier is now 350 m long. By 2016 the proglacial lake at the terminus had expanded to a length of 1850 m, a retreat of 800 m in 27 years.  The proglacial lake at the terminus of the eastern glacier in 2016 is 650 m long, indicating a retreat of 450 m.  In both case the retreat is a significant loss of overall glacier length, ~20%.  The purple arrow indicates the increasing separation between a tributary and the West Ganglung Glacier glacier.

Google Earth image of West Ganglung Glacier, red arrow is the 1991 terminus, yellow arrow the 2016 terminus, green arrow the eastern glacier proglacil terminus lake and purple arrow expanding zone between a former tributary and West Ganglung Glacier

 

Landsat image from2014 of West Ganglung Glacier, red arrow is the 1991 terminus, yellow arrow the 2016 terminus, and green arrow the eastern glacier proglacial terminus lake.

Torfajökull, Iceland Accumulation Zone Demise Drives Recession

On By mspeltoIn iceland glacier retreat

Torfajökull in 1994, adn 2014 Landsat images.  Note the lack of retained snowpack in 2014 and emerging bedrock areas within icecap, purple arrows.

Torfajökull is a small ice cap north of  Myrsdaljökull in Iceland.  The glacier’s lowest elevation is 750 m and the highest elevation is 1150 m.  This low of an elevation range in a climate driving higher snowlines places this type of ice cap at great risk for losing its accumulation zone and its ability to survive.   The Iceland Glaciological Society spearheads an annual terminus monitoring program led by Oddur Sigurðsson. In 2013 the report indicates all seven glaciers in the region near Torfajokull were in retreat.  In this post we look at the loss of the accumulation zone in 2014 and the longer term change in size noted by the Iceland Glaciological Society. This is not a good area for acquiring a suntan as the lack of clear imagery indicates for 2015 or 2016. 

In 2006 the Iceland Glaciological Society began monitoring the terminus of this glacier, the measurement is completed at the northeastern terminus.  From 2006-2014 the glacier has retreated 150 m.  The monitored terminus the location where areas of bedrock have begun to emerge from beneath the thinning ice cap, purple arrows. The bedrock areas exposed within the ice cap were not evident in 1994 images or the 2000 glacier outline. The loss of glacier area from 1946-2000 in the Iceland Glaciological Society map indicates area loss around the entire margin of the icecap including the highest elevations, located on the southern margin.  Recession at the head of a glacier suggests a glacier that lacks a persistent accumulation zone.

The change from 2000 to 2014 has been more pronounced on the eastern lobes that extend away from the main glacier.  The loss in ice cap area from 2000-2014 is ~10%.  In 2014 the glacier had 12% retained snowcover on August 12th, note Landsat image above and Google Earth below, by Sept.2014 there was no retained snowpack.  There is some retained firn the lightest blue, but even this is limited indicating that the snowpack from the previous few winters had not survived over most of the glacier either.

This is a recipe for glacier loss. The snowline on Aug. 12, 2014 shown below on Myrsdaljökull was at 1225 m, well above the top elevation of Torfajökull.  This glacier lacks the higher accumulation zone of some smaller Icelandic ice caps such as Eiriksjökull.

 

Iceland Glaciological Society map of glacier boundaries in 1890, 1946 and 2000, with the 2014 boundary added from the Landsat images above.  

Landsat image of Myrdalsjokull on 8/12/2014 with snowline at purple dots., 1225 m.

Sabbione Glacier, Italy Retreat & Fragmentation

On By mspeltoIn Italy glacier retreat

Sabbione Glacier in 1999, 2001 and 2016 Landsat images.  Red arrow is 1999 terminus location, red arrow the 2016 terminus location and the purple area new rock outcrops emerging in the midst of the glacier.

Sabbione Glacier is on the Swiss-Itlaian border.  The glacier drains into Lago Sabbione an artificial lake that in turn drains into Lago Morasco, which is a 29MW hydropower facility. The lake also has good fishing. This glacier in 1988 reached the shore of Lago Sabbione. Today glacier retreat has changed its nature dramatically.  It is not as close to disappearance as nearby Cavagnoli Glacier or Careser Glacier.  Huss and Fischer (2016) indicate that the majority of the small alpine glaciers, less than 0.5 square kilometers will disappear in the next 25 years.
In a series of Landsat images from 1999, 2001 and 2016 and a picture from Lago Sabbione in 2007, the retreat from the lake is evident. The 1988 terminus in an image below is indicated by a red arrow, the 2010 terminus by a yellow arrow, the new outcrop in the midst of the glacier by a magenta arrow. The retreat from 1988 to 1999 is 240 m, there is no rock outcrops emerging in 1999 or 2001. The glacier is 2.5 km long beginning at 3200 m and terminating at 2550 m in 1999. By 2007 image below the rock outcrop has become apparent. By 2016 the glacier has retreated 950 m from the lake and 700 m since 1999 and is now less than 2 km long.  The outcrop in the glacier center is 200 m wide. Of greater concern for the future of the glacier than retreat is the emergence of rock outcrops in the midst of the middle portion of the glacier, and smaller ones on the upper glacier. In 2016 the glacier only has 15% snow cover in this late August image, much less than the 50-60% needed for equilibrium balance. This indicates a glacier that is not in equilibrium lacks a persistent accumulation zone, indicating it will not survive current climate  (Pelto, 2010). In the most recent survey published by the Italian Glacier Commission indicates all glaciers in this region of Italy retreated in 2015.

Google Earth image of Sabbione Glacier and Lago Sabbione.


1988 Landsat image of Sabbione Glacier

Llewellyn Glacier, BC Proglacial Lake Merging From Retreat

On By mspeltoIn Canada glacier retreat, glacier climate change, Glacier Observations

Llewellyn Glacier comparison in 1984 Landsat and 2016 Sentinel images.  Red arrows the 1984 terminus locations for proglacial lakes A-D, yellow arrows the 2016 terminus locations for A and B. Point E was the peninsula separating proglacial lakes A and B, which are now joined due to glacier retreat. 

The second largest glacier of the Juneau Icefield is the Llewellyn Glacier which is in British Columbia. The Juneau Icefield Research Program has a research camp, C-26 on this glacier and it is the typical exit route from the icefield at the end of the field season.  Here we examine changes in the terminus from 1984-2016 as a result of higher snowlines indicative of an expanded ablation zone and negative mass balance. 

I first visited the glacier in 1981 and I was also on the icefield in 1984 when the Landsat image was acquired that is used as the start point for comparison. In 1984 the glacier had several termini ending in proglacial lakes A-D. We exited the glacier on the west side of proglacial lake A in 1984 onto a proglacial outwash plain referred to as the ball bearing highway.   At Point B the terminus ended in a deeper wider proglacial lake than Lake A. At Point C and D the glacier ended in a series of small lakes.  Point E is the peninsula separating proglacial lake A and B in 1984. Proglacial Lake B had a surface water level 10-15 m higher than Lake A in 1984. In 2011 the glacier still reached Point E  separating the two lakes, which still had different water levels. In 2013 the gap first opened between the two lakes, and the water level fell in Lake B. In the summer of 2016 and spring of 2017 the gap has persisted and widened to  150 m.  From 1984 to 2016 the terminus in Lake A has retreated 1300 m, the terminus at Lake B 2100 m, terminus at Point C 800 m and terminus at Point D 1100 m. The narrow tongue of ice at the pink arrow will not survive long. The crevasse pattern suggests the glacier has another 1.5- 2 km to retreat before lake development will cease. 

The snowline during the 1998-2013 period averaged 1900 m too high for an equilibrium balance.  In a sequence of images from 2013 illustrates the rise is snowline from  1450 m on June 21,  to 1780 m on August 1 and  1810 m on Sept. 2.   The persistently higher snowlines since 1990 have led substantial thinning, Melkonian et al. (2013) note thinning of more than 1 m per year at the terminus diminishing to little change above 1500 m from 2000-2009. This will drive continued retreat, supplemented by calving into the still growing proglacial Lake at Point A and B.  The retreat of this glacier follows that of other glaciers of the Juneau Icefield including nearby Tulsequah Glacier, noted by Pelto et al (2013) and Pelto (2016) .

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Upernavik, NW Greenland New Islands, Nunataks and Former Glacier Base Exposed

On By mspeltoIn Greenland glacier retreat

Upernavik Glacier in Landsat images from August 2000 and August 2016.  Each Point is at the same location in both image, and the changes are noted in the discussion below.  The same locations are also identified in the July 2001 and Aug. 2016 image below. 

Upernavik Glacier is on the NW Greenland Coast the next major outlet north of Rinks Glacier.  Today the glacier has four separate main calving termini, that was a single terminus until 1980. The retreat of this glacier is exposing new islands, nunataks etc that is examined in Landsat images from 2000 to 2016.   Howat and Eddy (2011) observed the terminus change of 71 outlet glaciers in NW Greenland from 2000-2010 and found that 98% had retreated. The retreat has occurred irrespective of the different characteristics of various glaciers (Bailey and Pelto, SkS).  Box and Decker (2011) note that ice loss for Upernavik Glacier’s combined termini was 7.9 square kilometers per year from 2000-2010.   Larsen et al (2016) observed asynchronous changes in dynamic behavior of four outlets of Upernavik between 1992 and 2013. Velocities were stable for all outlets at between 1992 and 2005. The northernmost glacier began acceleration and thinning in 2006 -2011. The second most northerly outlet began acceleration and thinning in 2009 and this continued through at least  2013. The southern glaciers showed little change.  They observed that the southernmost which is the focus here underwent a small deceleration between 1992 and 2013.  Velocity data for the 1999-2014 period of the southernmost outlet is available using an online map browser (Rosenau et al; 2015), indicates the highest velocity of the southernmost branch occurred in 2013 and 2014,  which would also lead to enhanced thinning.  Moon et al (2014) observed the velocity of the southernmost arm of Upernavik to have a velocity of 2-3 km per year with a modest seasonal velocity fluctuation of ~15%. They note that Upernavik Glacier is a type 2 glacier, exhibiting relatively stable velocity from late summer through winter into spring, followed by a  strong early summer speedup and midsummer slow down. 

Here we examine the changes from 2000 to 2016 at ten locations near the front of the southern most of the main outlets of Upernavik Glacier.  This reveals the formation of new islands, exposure of the former glacier bed and expansion of nunataks. 

Point 1: In 2000 and 2001 this is a nunatak just below the number that is separated by 500 m of glacier from the edge of the ice sheet.  In 2016 this point is a knob at the edge of the glacier.

Point 2: This is an area of bedrock, just below the number where the glacier terminates in 2000 and 2001.  In 2016 this is an island that is 2.5 km from the ice front.

Point 3: In 2000 and 2001 this indicates a small area of bedrock just above the number, that is less than 300 m across. In 2016 this is a large area of bedrock that is over 1 km across and is merging with other bedrock areas near the glacier front.

Point 4: Is a small area of bedrock just west of the number that is 2 km from the ice front in 2000 and 2001. In 2016 this area of bedrock has merged with bedrock at the terminus of glacier and extends 3 km from the ice front inland.

Point 5.  This is a region surround the number that is under ice in 2000 and 2001, there is a narrow rib of rock extending from the edge of the glacier to Point 5.  In 2016 a large area of the former glacier bed is exposed with numerous streamlined bedrock features.

Point 6 is a small area of bedrock in 2000 and 2001 that is 2 km from the glacier edge. In 2016 this has become an area that extends 1 km from north to south and has a narrow bedrock connection to the glacier edge.  The former glacier bed will continue to be expose between Point 5 and Point 6.

Point 7: In 2000 and 2001 this point marks the ice front where a medial moraine reaches the terminus.  In 2016 this is an area of bedrock that will either become a new island or merge with bedrock at Point 1.

Point 8: Just west of the number in 2000 and 2001 is a single small outcrop of bedrock less than 200 m across. In 2016 the area of bedrock extends south for 1 km from the main nunatak that is also expanding.

Point 9:  In 2000 and 2001 this location is covered by ice 500 m north of a nunatak.  In 2016 a new bedrock knob has emerged that will soon join the main nunatak.

Point 10: In 2000 and 2001 this location is covered by ice 5 km from the ice front. In 2016 a one kilometer long bedrock rib has emerged due to glacier thinning.

The retreat of this glacier exposing new islands and nunataks is repeated at Steenstrup Glacier, Alison Gletscher and Kong Oscar Glacier

Upernavik Glacier in Landsat images fromJuly 2001 and Aug. 2016.  Each Point is at the same location in both image, and the changes are noted in the discussion above.

View of the Upernavik four main calving fronts.  The focus here is on what is deemed the south trunk.  This is from the University of Dresden velocity map portal.