Nioghalvfjerdsbræ (79) Glacier, Northeast Greenland

On June 18, 2013June 18, 2013 By mspeltoIn Glacier Observations6 Comments

The Northeast Ice Stream in Greenland taps deeper into the heart of the Greenland Ice Sheet than any other glacier system. The ice stream has high velocities extending 700 km into the ice sheet, much longer than even Jakobshavn, first figure. This makes it a potential weakness for the northern sector of the GIS. The ice stream has three major outlets the Storestrommen, Zachariae and Nioghalvfjerdsbræ (79 Glacier). Fahnestock et (2001) identified that the initiation of fast flow occurred within 100 km of the ice divide and is driven by a high geothermal heat flux. Here we examine changes in the 79 Glacier using MODIS and Landsat imagery of the lower reach of the glacier. Nioghalvfjerdsbræ has a 20 km wide ice shelf, and the bed remains below sea level over a distance of 150 km upstream from the grounding line, and 200 km inland of the calving front, as indicated by the third figure below from Thomas et al, (2009).

Velocity of the Greenland Ice Sheet indicating extent of NE Ice Stream, (Bailey and Pelto, 2011).

Velocity map From Joughin et al (2010)

Bedrock Profile, surface profile and thickness change on a 79 Glacier Profile (Thomas, et al, 2009).

The most extensive field study of this remote glacier was conducted by GEUS(Geologic Survey of Denmark and Greenland) from 1996-1998(Thomsen et al. 1997). Thomsen et al (1997) denotes a floating ice tongue that is 60 km long and 20 km wide until expanding at the terminus to 30 km.They identified surface velocities in the terminus tongue section of the glacier, surface mass balance, ice thickness and bottom melting. he multi-year survey of the glacier by GEUS indicated that basal melting was approximately 4-5 m per year, much larger than the surface melt of 1 m per year. There works also indicates a rather uniform velocity for the floating ice tongue across the width of the glacier. Examination of ice thickness change on 79 Glacier indicates surface lowering predominated between 1994 and 1999, at rates of about 0.1ma–1, with almost exact balance further inland. Conditions were similar between 1999 and 2007, but with thinning rates increasing to about 0.3ma–1 over the seaward 150 km, and surface lowering of parts of the ice shelf by 0.5– 1ma–1 (Thomas et al, 2009).

Thomsen et al (2007) found surface velocities of 500 to 700 m per year in the region examined here, declining toward the ice front. The ice thickness declined from 325 to 175 m in thickness over a span 25 km in this same region. This is in a zone of limited change in width and most of the change has to be from basal melting. Given velocities observed of 600 m/year this would indicate a thinning of 150 m in a span of 40 years to traverse this reach. This would be a thinning for nearly 4 m per year via basal melting, a similar magnitude to the direct borehole observations.

Seroussi et al (2011) indicate the velocity declining from 800 m/year to 600 m/year in the reach examined here.

Velocity of 79 Glacier and Zachariae Ice Stream from Jougin et al (2010).

Joughin et al (2010) observed no significant change in speed for the inland part of the Northeast Greenland Ice Stream. They further noted that for 79 Glacier there was no significant speed-up, and any change visible on its floating ice shelf can be attributed to tidal effects. Straneo et al (2012) found that the warmest (deep) AW is found near Helheim, Jakobshavn and followed by Kangerdlugssuaq and 79, with Petermann having the coldest. This suggests that basal melting can be an even more significant volume loss than on Petermann.

Here we pay particular attention to a section of the glacier that is 20-40 km from the calving front. A series of Landsat images from 2001 to 2013 track specific features as they move down glacier. The features A-D are each adjacent to specific unique features, specific meanders in two supraglacial streams. The movement of these features indicate the velocity over the 12 year period in this region, approximately 600 m/year. This agrees with the more detailed analysis of Seroussi et al (2011) , Thomas et al (2009) and Thomsen et al (1997). Further the spacing of these points has not changed indicating that the glacier in this region is moving as a single unit with relatively similar velocities. Further the persistence of the same streams and the ponds indicates The surface melting has led to development of numerous ponds and streams on the surface of the glacier. The lack of drainage of these features indicates the lack of crevassing, rifting or moulins to deliver water to the base of the glacier. The Petermann Glacier had several prominent rifts running transverse to glacier flow, that were clear weaknesses that would lead to future calving. 79 Glacier lacks such large rifts, just upstream of Point A is a prominent feature that at least at this point is not a rift. Pat Lockerby has noted these features in MODIS, but given the lack of water drainage and distinct break, these are not currently cracks.

2001 Landsat image

2004 Landsat image

2009 Landsat image

2011 Landsat image

2013 Landsat image

The second set of images indicates the change in terminus position at the northeastern terminus from 2000 to 2011, purple dots, often referred to as Spaltegletscher. The yellow arrow indicates a longitudinal rift that has developed since 2000 that is nearly connected to another rift near the margin of 79 Glacier. Espen Olsen at the Arctic Sea Ice Forum has suggested that this is what will lead to this area breaking off. The orange arrow indicates the same location marking the terminus of the glacier at its northwest corner. The last image is from June 16, 2013 this MODIS image indicates the two rifts red and yellow arrow at the start of the Spaltegletscher terminus. Followed by Landsat image from June 17, 2013 indicating the new terminus position more clearly and the same rifts. Another iceberg has peeled off since 2011, and the total ice loss since 2001 is 70-80 square kilometers. Jason Box, Ohio State had noted a loss of about 50 square kilometers from 2000 to 2010. Also apparent is an area of active calving and icebergs in front of Zachariae, check out the new icebergs in the June 17, 2013 Landsat atZachariae Ice Stream
2000 Landsat image

2010 Landsat image

2011 Landsat image

June 16, 2013 MODIS image, yellow and red arrows indicate two rifts at the start of Spaltegletscher.

June 17, 2013 Landsat Image

Qinngua Avannarleq Retreat, Southwest Greenland

On June 13, 2013 By mspeltoIn Glacier Observations1 Comment

Qinngua Avannarleq is at the head of Evighfjorden an arm of Kangerlussuatsiaq Fjord in southwest Greenland. Leclercq et al (2012) notes the glacier is 15 km long and has an area of 57 square kilometers. They further note that the glacier retreated 0.5 km from 1850-1960. Here we examine Landsat imagery from 1996, 2000, 2009, 20011 and 2012. In each image the yellow arrow points to a tributary from the northeast that met the glacier at the terminus in 1996, the red arrow indicates the 2012 terminus location and Points A-D identify locations where bedrock exposure is expanding with glacier thinning. In 1996 and 2000 the terminus was 1.8 km wide and merged with a tributary from the north right at the terminus. In 1996 and 2000 Point C and D are uninterrupted glacier cover. At Point A and B there are narrow glacier tongues passing between rock exposures. By 2011 and 2012 the terminus has retreated 1.3 km from the 1996 position. At Point A the tributary that separated the rock outcrops has now disappeared leaving uninterrupted rock. At Point B the bedrock area has expanded and the narrow tributary no longer connects to the main glacier. At Point C a ridge of bedrock has extended 1 km further into the ice cap. At Point D a new bedrock knob has emerged amidst the main glacier. The retreat of over 1 km since 1996 is a greater retreat than had occurred from 1850-1990 (Leclerq et al (2012). The retreat of this glacier is similar to that of Narssap Sermia Glacier and Qaleriq Glacier. A nunatak 12 km inland also indicates thinning with a stranded section of ice, red arrows. This area also features very dirty ice, black arrows, that increases the albedo, which bring to mind the Dark Snow Project.
1996 Landsat Image

2000 Landsat Image

2009 Landsat Image

2011 Landsat image

2012 Landsat image

Canada Glacier Retreat Post Index

On June 12, 2013 By mspeltoIn Glacier Observations1 Comment

Canada Glacier Index
Canada has more than 20,000 glaciers spread across its arctic islands and in the mountains of the western provinces. Below is a list of 32 glaciers in Canada that are all retreating and chronicled glacier by glacier. I have had the pleasure of working on 10 Canadian glaciers.

Great Glacier, National Railroad Archive 1914 image.

Neve Glacier Retreat, North Cascades, Washington

On June 10, 2013June 10, 2013 By mspeltoIn Glacier Observations

I have had the opportunity to visit the Neve Glacier on eight occasions, it is not easy to get to. In the North Cascades it is one of a handful of glaciers with a large higher elevation accumulation zone, that is not on a volcano. The glacier feeds Diablo Lake, part of the Skagit River hydropower system. The terminus of the glacier in 1975 was in basin that receives considerable avalanche deposition slowing the retreat. In this post we focus on the thinning of the glacier leading to expansion of bedrock exposures at four locations above the former terminus, that by 2011 had led to this low lying basin being dynamically cutoff from the upper glacier. In each image the red letters A-D are located in the same spot, and the purple arrow on the Google Earth images indicates the terminus position. The first image is an aerial view of the glacier from Austin Post, USGS from 1975: at point A there is a quite small exposure of bedrock, at Point B and C there is a good connection of feeder glaciers from the higher slopes to the main valley glacier. At Point D there is continuous glacier cover. This was the case during my first two visits to the glacier in 1985 and 1988, second image. The third image is from 1990 and reflects limted change from 1975 as well, the blue arrows indicate glacier flow.

. By 1996 notable thinning of the glacier was apparent adjacent to Point A, in 2001 and 2002 the thin nature of the ice around the bedrock at Point A is evident.

. The accumulation zone of the glacier around Point B and D in 2001 indicates no bedrock exposure at D and a connection of the upper glacier at Point B; however at Point D in 2009 the large new bedrock areas that have resulted from thinning has occurred.

A comparison of the Google Earth imagery from 1990, 2006 and 2009 indicate the expanding bedrock at each Point. A closeup of Point A from 2009 has the bedrock delineated with red dots indicating that the left arm of the glacier that formerly encircled Point A, now ends above Point A and that the right hand arm is only 35 m wide and despite the steep slope has no crevassing and is stagnant. At Point B the upper glacier no longer reaches the main trunk. At Point C the connection to the main glacier has decreased by 50% in its width from 140 m to 70 m, and at Point D several large bedrock areas have emerged.

In 2013 or 2014 the upper glacier will likely separate from the former terminus region below the Point A bedrock region. The thinning of this glacier is typical of North Cascade glaciers (Pelto, 2007), though the retreat has been unusually small (Pelto, 2010).

Excelsior Glacier Retreat, Alaska

On June 6, 2013June 6, 2013 By mspeltoIn Glacier Observations3 Comments

Excelsior Glacier in Alaska has terminated in a lake for the last century. Here we examine the retreat of this glacier from 1984 to 2011 using Landsat imagery. This glacier is seen as a model for the impending retreat of Brady Glacier examined in a paper we just published (Pelto et al, 2013). In 1909 the glacier ended on the strip of forested land between the lake and the ocean (Molnia, 2007). By 1950 the glacier had retreated 2 km from this strip of land creating the new lake (USGS-Molnia, 2008) In 1909 the glacier had ended on land at the south end of the lake, indicating a retreat of 4.5-5.0 km in approximately a 75 year period. In 1984 (first image below) Excelsior Glacier ended at the pink arrow and the lake extending beyond the terminus was 4.7 km long, the yellow arrow indicates the 2011 position and just south (under) the arrow is a glacier dammed lake. The lake width has changed little and is 1.4-1.8 km wide in the region the terminus has been retreating through during the last 30 years. By 1989 the glacier had retreated 500 m and the lake was filled with numerous icebergs. By 2001 the glacier had retreated 1500-1700 m from the 1984 position, a rate of 100 meters per year, and the glacier dammed lake south of the yellow arrow is still apparent, as are a couple of large icebergs. The 2003 Google Earth image indicates further retreat and again a couple of large icebergs and a large crack near the center of the terminus indicating a new iceberg getting ready to separate. By 2011 the glacier had retreated past the formerly glacier dammed lake and ended at the prominent ridge just north of this former lake and the new inlet that replaces it. The glacier has retreated 3400-3700 m depending where on the front the measurement is made. This is a rate of over 100 meters per year since 1984.
Another big change is the thinning and narrowing of the tributary entering on the east side of the glacier north of the terminus. This is illustrated in the last image with a combined 1989 image left and 2011 rigth and the red arrows pointing out three significant points of thinning and new rock-moraine exposure. This glacier has behaved in a similar fashion to so many Alaskan glacier from the nearby Bear Glacier, to British Columbia’s Melbern Glacieror Porcupine Glacier and southeast Alaska’s Chickamin and Norris Glaciers of southeast Alaska

1984 Landsat Image

1989 Landsat image

2001 Landsat image

2003 Google Earth image

2011 Landsat Image

1989-2011 Landsat image

Zayul Chu Headwaters Glacier Retreat, Tibet, China

On June 3, 2013 By mspeltoIn Glacier Observations1 Comment

The headwaters of the Zayul Chu River is a series of glaciers. This river becomes the Lohit River as it enters India. The impact of glaciers is visible just from the color of the water, the greenish tone being generated from glacier flour. The Lohit River is also the focus on a hydropower development plan that proposes six dams that would generate 7450 MW.

Glaciers at the Headwater of Zayul Chu noted by red, yellow and purple arrows.

Map of proposed Hydropower Project for Lohit River, yellow arrows indicate dams.

Table of hydropower characteristics for six proposed sites on Lohit River.

Lohit River, color indicates glacier contribution

Here we examine three glaciers that have seen lake expansion at the terminus in the last 25 years using satellite imagery from 1987, 1996, 2009 and 2011. In 1987 there was no lake at the end of the glacier ending at the purple arrow. In 1987 the glacier ending at the red arrow, ended in a narrow lake. At the yellow arrow the glacier ended in a small round lake in 1987. By 1996 the glacier at the red arrow has retreated leading to a lake that is 100 m longer than a decade before. The glacier at the yellow arrow has pulled from the lake it had ended in. In 2009 a small lake has formed at the end of the glacier with the purple arrow, a distance of 200 m. The glacier at the red arrow has retreated from the lake it had formerly ended in, a distance of 400 m. The glacier at the yellow arrow has retreated 200 m from the lake it had ended in. Each of these glaciers ends between 4200 and 4600 m and begins above 5300 m. The glaciers retain snowpack on the upper reaches each summer and will continue to retreat but can survive current climate. The retreat of the Zayul Chu headwaters glaciers parallels those of the Bode Zangbo Headwaters a short distance to the north and the Hkakabo Razi Glaciers a short distance south.

1987 Landsat image

1996 Landsat image

2009 Landsat image

2011 Landsat image

Hkakabo Razi Glacier Retreat, Myanmar and China Border

On May 30, 2013 By mspeltoIn Glacier Observations3 Comments

Hkakabo Razi is the highest peak in Myanmar and straddles the border with China. The Myanmar side (east) of the mountain drains into the Irrawaddy River and on the China side (west) to the Brahmaputra River. First of all how many people thought Myanmar had glaciers? Secondly this is a remote peak that only one party has managed to climb. In the Google Earth image the blue arrows indicate icefall regions and the direction of flow into these areas. Here we examine the changes in several glaciers using Landsat imagery from 1987, 1996 and 2009. The red arrows indicate several locations in each image where in 1987 and 1996 sections of a each glacier coalesce. By 2009 in each of the red arrow locations the sections of the glacier have separated. The change in terminus position of three glaciers is also noted, the yellow dot indicates the terminus of the main west flowing glacier. The retreat from 1996 to 2009 is 250 m. The green dot indicates a location at the terminus of an east side glacier. In 1996 the terminus is at the down slope side of the dot and in 2009 the terminus barely reaches the up slope side of the green dot a retreat of 200 m. The pink arrow indicates the terminus of a steep east side glacier. In 1996 the glacier ended at a prominent cleft in the rock, pink arrow and by 2009 had retreated 200 m from this feature. These glaciers have behaved in a similar fashion to Hailuogou Glacier and the glaciers at the headwater of the Bode Zangbo.
1987 Landsat image

1996 Landsat image

2009 Landsat image

Bode Zangbo Headwaters Glacier Retreat, Tibet, China

On May 27, 2013May 27, 2013 By mspeltoIn Glacier Observations3 Comments

In the eastern portion of the Nyainqêntanglha Shan, there is a raindrop shaped group of mountains encircled by the Bode Zangbo to the west and Yu Chu Zangbo (maps indicate several names here) to the the east. At the headwater of the Bode Zangbo are a series of glaciers ending in valley occupied by several new lakes formed by glacier retreat. The Bode Zangbo is the site of a proposed new 9600 kW hydropower project financed by Datang Power International. The Bode Tsangbo than joins the Parlung Zangbo and then Yarlung Tsangpo that becomes the Brahmaputra River in India. Both of the latter rivers are the focus of ongoing intensive hydropower development as indicated by the map from Tashi Tsering, with most existing dams being upstream on the Yarlung, red arrow indicates glacier site. Here we focus on two glaciers in particular indicated by a red and yellow arrow in each Landsat or Google Earth image. Both glaciers are unnamed. In fact the first image is the area in general from Google Earth with all the layers activate to show names, and there are none in this mountain region. In the lower left of the image China National Road 318 is visible that in this region connects Bomê County and Nyingchi.

The red arrow indicates a glacier that was 3 km long in 1986 beginning at 5500 m and ending at a moraine at 4900 m. The red arrow points to the low lying terminus piedmont lobe. The second glacier ends in a lake, with the yellow arrow indicating a peninsula on the northeast side of the lake where the glacier ends in 1986. The blue arrow simply indicates the drainage direction of the stream. In 1986 the Bode Zangbo Headwaters Glaciers at the red arrow has no lake at its terminus, the terminus has a toe that turns south down the main valley to end at a series of moraines. By 1999 a tiny lake is evident. In 2000 and the 2001 Google Earth image the lake is still barely detectable. By 2011 a full fledged deep blue lake has developed, where the terminus of the glacier had been. The lake is 600 m long and 400 m long, indicating a 550-600 m retreat in the last decade of the glacier. At the yellow arrow there is limited change from 1986 to 2000, with the glacier still ending in proximity to the peninsula. By 2011 the glacier has retreated 350 m from the 1986 position. The other glaciers in the valley have also been in retreat, but given the location of the scan line errors and clouds it is harder to point out the specific retreat. The yellow dots in the late summer 2011 image indicates the snowline at 5150 m. This is the same snowline and terminus behavior as noted for Jiongla Glacier 110 km west northwest. The glacier follows the pattern of many other glaciers retreating in the region leading to lake expansion, Longbasba Glacier.

1986 Landsat Image

1999 Landsat Image

2000 Landsat Image

2001 Google Earth Image

2011 Landsat Image

Jiongla Glacier Retreat, Tibet, China

On May 23, 2013May 27, 2013 By mspeltoIn Glacier Observations3 Comments

Jiongla Glacier is at the northern boundary of the .Brahmaputra River Basin.) at the east end of the Nyainqentanglha Shan. The glacier drains the western slopes of Koma Kangri Peak and ends in a lake before feeding into the Parlung Zangbo and then Yarlung Tsanpo. Ninglian and Shichang (2010) in the China National Report on Cryospheric Sciences noted a loss in glacier area of 15 to 17 % in the region. ICIMOD (2011) notes that the basin has 11, 500 glaciers covering an area of 14,000 square kilometers. Here we examine satellite imagery from 19988, 2000, 2009, 2010 and 2011. The pink arrow denotes the 1988 terminus and the yellow arrow the 2011 terminus.
2003 Google Earth image

In 1988 the lake where Jiongla Glacier ends is at 4000 meters and is 2 km long. By 2000 the glacier has retreated 1300 meters. By 2009 the lake is 4 km long, a 2 km retreat in 20 years. The retreat from 2009 to 2011 is not evident in the satellite imagery used here. There are icebergs visible in the lake particularly in the 2003, 2009 and 2011 images indicating that this one a key reason for rapid recent retreat. In reviewing the satellite images for the region cloud cover made it difficult to find imagery near the end of the melt season. The 2011 image is from near the end of the melt season and indicates a snowline at 5150 m, green arrows, this is too high for equilibrium, with limited glacier area above 5500 m and the terminus at 4000 meters. This suggests that retreat will continue. The last image is a 2003 terminus closeup that indicates vigorous flow through an icefall, red arrow, 2 km behind the terminus. This indicates the lake will end before this point and the glacier does not have a substantial stagnant terminus tongue. This also suggests the rate of retreat will soon slow. The retreat here is similar to that of Sepu Kangri Glacier and Requiang Glacier. This glacier feeds the Parlung Zangbo which is the site of numerous planned hydropower projects, last image, . before joining the Yarlung Tsanpo which becomes the Brahmaputra River
Landsat image 1988

Landsat image 2000

Landsat image 2009

Landsat image 2010

Landsat image 2011

Galaxy Glacier Rapid Retreat, Pukulkul Basin Glacier disappears, British Columbia

On May 21, 2013 By mspeltoIn Glacier Observations2 Comments

Over the ridge south from Stave Glacier is a 1.5 km long unnamed glacier, that is on the west flank of Galaxy Peak, hence referred to here as Galaxy Glacier. The glacier is in Garibaldi Provinical Park, British Columbia. Koch et al (2009) in their detailed survey of glaciers in the park chronicled the Park’s glacier retreat from 1952 to 2002. Koch et al (2009) Found that all 45 glaciers are retreating, and Stave Glacier was experiencing its fastest retreat from 1976-1996, with a 750 m retreat. Satellite imagery from 2012 indicates the Stave Glacier retreat rate from 1996 to 2012 is 1600 m or 100 m per year, even faster. Here we utilize Landsat imagery from 1985, 1987, 1992 and 2009, plus Google Earth imagery form 2006 to examine the retreat and separation of Galaxy Glacier. The orange arrow indicates the terminus of the Galaxy Glacier (G) in 1985 where it joined the glacier (P) in the Pukulkul Basin where several lakes have been forming. This basin is just north of Pukulkul Peak. In 1985 Galaxy Glacier and the Pukulkul Basin Glacier are joined at the orange arrow, the red arrow marks the 2009 terminus and the purple arrow indicates the connection to the highest accumulation area on the east slope of Corbold Peak. By 1987 Galaxy Glacier has separated from the Pukulkul Basin Glacier, the latter has an area of 0.45 square kilometers and is larger than the lake it ends in. By 1992 the Galaxy Glacier is separated by 500 meters from Pukulkul Basin Glacier. The area of bare rock at the purple arrow at the top of Galaxy Glacier has expanded. By 2006 the Pukulkul Basin Glacier is gone and a 2.5 km long series of lakes is in its place. Galaxy Glacier has retreated 800 m from the new lake, and 650 meters from its 1985 position. The purple arrow indicates two large rock outcrops effectively ending significant glacier inflow from the upper east slopes of Corbold Peak. By 2009 the Pukulkul Basin Lake has a deeper blue as the glacier input has declined. The glacier is 90% bare of snowcover and the bedrock at the purple arrow has continued to expand. A closeup of the glacier from the 2006 Google Earth imagery indicates exposed firn layers at the blue arrows. This indicates that all the snowcover not just from the most recent winter has been lost but a number of previous winters as well. This is indicative of a glacier that has no consistent accumulation zone and cannot survive (Pelto, 2010). This glacier similar to the nearby Helm Glacier cannot survive current climate. The purple arrows indicate the limited connection to the upper slopes of Corbold Peak. The red arrow indicates the current terminus position. Galaxy Glacier has lost half of its area in the last 25 years, and the 800 m retreat is one-third of its total length.
1985 Landsat

1987 Landsat

1992 Landsat

2006 Google Earth

2009 Landsat

2006 Google Earth Cloesup

Malavalle Glacier Retreat, Italy

On May 19, 2013May 20, 2013 By mspeltoIn Glacier Observations2 Comments

Malavalle Glacier is an Italian glacier draining south from the Austrian border. The glacier has an interesting cartographic history with maps spanning several centuries indicating its evolution. The Italian Glaciological Committee indicates the retreat of this glacier from 1938 to 2004, from 1938 to 1958 the glacier retreated 500 m. A map from 1937 provided by Nicholas Fisher indicates the terminus of the glacier, with the orange arrow indicating the location of a lake that the glacier ended in 1985, the yellow arrow the 1937 terminus and a purple arrow the location of a prominent ridge. Below the indicated lake in 1937 the glacier descended a steep icefall and then had a gentle terminus. The rapid retreat to 1958 removed the entire section of the glacier on and below this icefall. The second image is a 2002 view of the glacier from Google Earth, the red arrow indicate two small proglacial lakes that formed. From 1958 to 1978 the retreat essentially ended, with just 30 m of retreat. From 1978 to 2004 recession accelerated with 180 m of retreat. Here we examine Landsat imagery from 1985, 1990, 2000, 2010 and 2011 to identify a retreat of 540 meters from 1985 to 2011. In each image the orange arrow indicates the location of the lake where the glacier terminated in 1985, and in 2011 the purple arrow indicates the 2011 terminus. In 1990 there is a narrow strip of rock between the glacier and the lake. By 2000 the glacier has further retreated from the lake, and the majority of the glacier is bare ice. In 2010 snowpack on the glacier is again limited. In 2011 the terminus has not only retreated 540 m from the lake, but the current terminus is also quite narrow. The last image is from the Italian Glaciological Committee of the glacier showing the terminus position from 1885 to 1997. The retreat is similar to that of Lobbia Glacier and Sabbione Glacier. However, Malavalle has a higher elevation accumulation zone above 3100 meters below the summit of Wilder Freiger that continues to retain snowpack.
1985 Landsat

1990 Landsat

2000 Landsat

2010 Landsat

2011 Landsat

Lake Cachet 2 Jökulhlaup Colonia Glacier, Chile

On May 15, 2013 By mspeltoIn Glacier Observations

Colonia Glacier drains east from the Northern Patagonia Icefield feeding the Rio Colonia and then Baker River, Chile. A Feb 8th 2013 Landsat image caught the impacts of a jökulhlaup in progress, glacier lake outburst flood. This post examines the filling and emptying of Cachet Lake 2 and its impacts and the continued retreat of Colonia Glacier. The glacier is unusual in the number of lakes that are adjacent to or feed into the adjacent glacier dammed or proglacial lakes. In the image below Lake A=Arco Lake, Lake B=East Terminal Lake, Lake C=Cachet, Lake D= West terminal Lake, Lake E=Colonia Lake and Lake F=Cachet 2. The glaciers recent retreat has been closely monitored by the Laboratorio de Glaciología in Valdivia, Chile. Aniya and others (1999)observed that Colonia Glacier began a rapid retreat after 1985, with a comparison of a RADARSAT image from 1997 and a Landsat 1987 image indicating a retreat of 400 m. From 1997-2005 the retreat has further accelerated, with a general frontal retreat of 2.5 km. The retreat has continued to 2013 as examined below.

In the spring of 2008 Baker River suddenly tripled in size, in less than 48 hours, roads, bridges, and farms were severely damaged. Lake Cachet 2 had vanished the 5 square kilometer glacial lake had emptied 200 million cubic meters of water in just a matter of hours. This lake drained beneath the glacier after sufficient water had filled the lake to buoy part of the glacier and subglacial conduits had begun to develop. Since Cachet 2 emptied in April 2008, the lake has emptied thirteen times, with the Feb 7-8 release in 2013 the most recent. In 2008 the General Directorate of Water (DGA) setup a station to monitor the water level and telemeters this information, so that any outburst can be quickly identified. The two pictures below are of the Lago Cachet 2 basin filled and empty
In this case notification came from Fabian Espinoza at the DGA.
Below is a sequence of images from Sept. 17, 2012 when the lake is full, then on Feb. 8, 2013 just as the lake is finishing draining and then on March 28, 2013 after the lake has mostly refilled. The yellow arrow indicate Lago Cachet 2, the red arrow where the terminus has its last connection to a peninsula between the two proglacial terminus lakes and the purple arrow to the outwash plain between the proglacial terminus lake and Lake Colonia. In the Sept. 2012 image the east terminus lake has its normal water level and the outwash plain is 3 km long between the lakes. On Feb. 8th the water level in both Colonia Lake and the east and west terminus lake have been raised and most of the outwash plain is flooded. Even Colonia Lake has risen considerably, notice the southeastern edge of the outwash plain flooded by the outburst. By March 28, 2013 Lago Cachet is mostly filled again and the outwash plain is normal. The terminus connection to the red arrow peninsula has declined in width from 1 km in 2012 to less than 500 m by March 2013. The Feb. 2013 image indicates that the high water level in the terminus lakes partially submerged the terminus.
Sept. 17 Landsat

Feb. 8 Landsat

March 28, Landsat

The terminus of the glacier continues to retreat and its area in the proglacial terminus lake basin contract. Below is a sequence of images from 1999, 2003, 2005, 2011 and 2013. In 1999 the terminus lakes barely exists. By 2004 the lakes have a combined area of 1.4 square kilometers. In the Google Earth image from 2005 this has expanded to 2.3 square kilometers. By 2012 the terminus lakes have expanded to an area of 4.0 square kilometers, and the glacier terminus has lost the same area. The connection to the red arrow peninsula will be lost very soon, which should lead to further terminus tongue breakup. This is much like the breakup observed at Glaciar Steffen and Glaciar Gualas