Tag: Featured

Soler Glacier Retreat and Lake Expansion

On By mspeltoIn chile glacier melt, chile glacier retreat

Soler Glacier in 1987 and 2020 Landsat images.  Red arrow indicates 1987 terminus location, yellow arrow indicates 2020 terminus location on north side of glacier.  Yellow dots indicate margin of lake and purple arrows indicate specific locations where glacier thinning is evident.

Soler Glacier is an outlet glacier on the east side of the Northern Patagonia Icefield (NPI). The terminus response of this glacier has been slower and more limited than on most NPI glaciers.  Aniya and Fujita (1986)  reported a total retreat of 200-350 m from 1944 to 1984.  Glasser et al (2016) note the recent 100 m rise in snowline elevations for the NPI, which along with landslide transport explains the large increase in debris cover since 1987 on NPI from 168 km2 to 306 km2 .  Loriaux and Casassa (2013) examined the expansion of lakes on the Northern Patagonia Ice Cap reporting that from 1945 to 2011 lake area expanded 65%, 66 km2. For Soler Glacier lake formation did not occur until the last decade and debris cover has changed little as well. Willis et al, (2012) identified thinning of ~2 m/year in the ablation zone from 1987-2011. This thinning is now leading to the development of a significant proglacial lake that is examined using Landsat images from 1987-2020.

In 1987 the glacier is still up against the Little Ice Age moraine, though it had thinned considerably resulting in retreat down the slope of this vast moraine. By 2000 a small lake had developed both on the north and south side of the main terminus with a total area of ~0.3 km2, red dots. In 2016 and 2019 this lake had expanded, with the northern arm mostly filled with ice, orange dots.  In October 2020 the lake has an area of ~1 km2 and is mostly open water. The extensive thinning of the terminus tongue continues to drive both retreat and lake expansion.  The thining is evident at Point A where bedrock knobs have emerged from the ice near the snowline.  The three purple arrows on the south side of the glacier indicate thinning as these bedrock features are increasingly distant from the glacier. The terminus has retreated 500 m in the glacier center, 2100 m on the north side and 1300 m on the south side from 1987-2020.  The terminus tongue in its lowest 1.5 km continue to thin and will collapse in the lake in the near future. The end of summer snowline has averaged 1450 m in recent years leading to continued mass loss without calving in the lake (Glasser et al 2016).

Lake development here lags that of other glacier around the NPI such as Exploradores, Nef, Steffen and San Quintin.

Soler Glacier in 2000 and 2019 Landsat images.  Red arrow indicates 1987 terminus location, yellow arrow indicates 2020 terminus location on north side of glacier.  Red dots  and orange dots indicate margin of lake.

Soler Glacier in 2016 Landsat image.  Red arrow indicates 1987 terminus location, yellow arrow indicates 2020 terminus location on north side of glacier.  

Coley Glacier and Sjögren Glacier, Antarctic Peninsula Exhibit Rapid Melt Feb. 2020

On By mspeltoIn Antarctic Glacier retreat

Coley Glacier in Landsat images from Feb. 4, 2020 and Feb. 13, 2020. Magenta dots indicate the snowline

The impact of a period of record warm weather over the Antarctic Peninsula during February 2020 was rapid development of melt features and expansion of melt area on many glaciers near the tip of the Peninsula, where the temperature records were set at Esperenza and Marambio Base. Here we examine Landsat imagery at Coley Glacier on James Ross Island and Sjögren Glacier to identify surface melt extent and surface melt feature development (see map below). Coley Glacier is 30 km west and Sjögren Glacier 120 km west of Marambio Base respectively. Xavier Fettweis, University of Liege Belgium, used the MAR climate model output forced by the Global Forecast System (GFS) to generate daily melt maps for Antarctica, for Esperanza the melt map indicates that daily melt increased to above 30 mm/day on Feb. 6, with a maximum temperature on the warmest day of 18.3 C (65 F). The impact was noted at Eagle Island Ice Cap and  Boydell Glacier where melt ponds and melt saturated snowpack quickly developed. On Eagle Island Ice Cap melt averaged 22 mm/day ffrom Feb 6-Feb 11(Xavier Fettweis, 2020).

Coley Glacier retreated ~1.5 km from 2001-2015.  On Feb. 4 snowcover extends to the terminus of the glacier, this is a thin snowpack resulting from a recent summer snow event.  The bay is also largely filled with sea ice.  Nine days late on Feb. 13 the bay is free of sea ice and the snowline has rise to 400 m, at the base or just on top of the escarpment.  The loss of snow and sea ice in just nine days is a remarkable melt rate for Antarctica. On March 7 2020 the snowline is also at 400 m and melt plumes are evident at the glacier front indicating ongoing melt conditions.

Coley Glacier in March 7, 2020 viewed in the Antarctic REMA Explorer

Sjögren Glacier retreated 10-11 km from 2001-2016. On Sjögren Glacier on Feb. 11 the snowline is at 500 m, compared to ~200 m on January 12, having shifted 8 km upglacier. The false color Landsat image, deep blue coloration below the snowline indicates the presence of meltwater at the surface. Melt plumes are evident at the glacier front, yellow arrows.  The snowline is still at 500 m on March 7, with meltwater plumes indicating that significant meltwater is still exiting the glacier. The lower 15 km of the glacier was in the ablation zone for an extended period during the Antarctic summer of 2020.

The above examples added to those at Eagle Island Ice Cap and  Boydell Glacier illustrate the extent of the melt event.

Sjögren Glacier in Landsat images above from Feb. 11, 2020 and below from March 7, 2020 viewed in the Antarctic REMA Explorer.  Yellow arrows indicated meltwater plumes and magenta dots the snowline. Contours are at 100 m intervals.

Sjögren Glacier in Feb. 11, 2020 Landsat image indicating snowline with magenta dots.  The areas with significant surface meltwater have a deep blue color.

Base map for region indicating Esperanza Base=ES, Marambio=M, James Ross Island=JRI, Coley Glacier=C, Sjogren=Sj and Eagle Island=EI

Gangotri Glacier, India Smallest Observed Accumulation Zone in 2020

On By mspeltoIn India glacier retreat4 Comments

Gangotri Glacier snowline averaging 5600 m on Oct. 16, 2020 in Landsat image, magenta dots indicate the snowline.  Yellow line is the Randolph Glacier Inventory margin. Tributaries: K=Kirti; G=Ghanohim, Su=Sumeru, M=Maiandi, S=Swachhand.

Gangotri Glacier, India is in the Bhagirathi River watershed and is the largest glacier in the Garhwal Range of the Himalaya.  Gangotri Glacier supports hydropower as its meltwater runoff passes through three hydropower plants generating 1430 Megawatts including the  Tehri Dam, Maneri Bhali I and II.  From 1968-2006 the glacier retreated 800 meters, ~20 meters/year (Bhambri et al 2011). The glacier has continued to thin and tributary inflow has declined with a tributary (Chaturangi) separating during this period .  Bhambri et al (2011) noted that recession rates have in the region have increased since 1990.  Bhattachaya et al (2016) expanded on this work noting that the velocity of Gangotri Glacier declined during 2006-2014  by 6.7% from 1993-2006, indicating a reduced volume of accumulation flowing downglacier. They also noted an increase in the rate of debris-covered area expansion on the main trunk of Gangotri Glacier from 2006-2015, indicative of an expanding ablation zone. Bhattachaya et al (2016)  report a retreat rate of 9 m/year 2006-2015, which is less than before, but the down-wasting in the same period 2006-2015 was higher than during 1968-2006.

Gangotri Glacier boundary and flow directions on Digital Globe image with GLIMS glacier outline indicated.

Gangotri Glacier is a summer accumulation glacier with the peak ablation period low on the glacier coinciding with peak snowfall high on the glacier during the summer monsoon.  In the post monsoon period of October and November precipitation is low and melt rates decline. Kundu et al (2015) noted that from Sept. 2012 to January 2013 the snowline elevation varied from 5080 m to 5174 m . This contrasts to an ELA of 4875 m reported by (Bhattachaya et al 2016) and 5100 m (Bhushan et al 2017).

On October 9, 2016  the snowline was at 4850 m on the main trunk and on the tributary Ghanohim Glacier, and 4750 m on the tributary Kirti Glacier.  By November 30th a Landsat image indicates the snowline has risen to 5400 m on the main trunk and Ghanohim, the snowline is at 5800-5900 m on the glaciers in the Swachhand tributary valley, at 5600 m on Maiandi Glacier and 5700 m on the last tributary entering from the north. A Landsat image from Dec. 9th indicate that the snowline remains approximately the same as on Nov. 30th. The substantial post monsoon snowline rise in 2016 is illustrated in this article on Gangotri Glacier.

Gangotri Glacier snowline purple dots in Landsat 11-30-16 image, red arrow is terminus.

On October 16, 2020 a warm/dry post monsoon season has led to the snowline rising rapidly on Gangorti Glacier. On Kirti the snowline is at 5500 m, on Ghanohim at 5400 m, on Sumeru at 5500 m, on the main stem 5600-5700 m, on Maiandi at 5700 m and on Swachhand at 5800 m.  The snowline is averages 5600 m the same as in 2016.  Below the snowline there is limited older firn exposed, indicating that limited snow is retained below 5400 m on Gangotri Glacier from year to year. The bare glacier ice has a lower albedo then snow increasing melt and further reducing glacier mass balance.

The accumulation area ratio is the percentage of a glacier in the accumulation zone and is typically above 50% for a glacier in equilibrium.  On Gangotri Glacier in November 30, 2016 the accumulation area ratio was 20-24%, indicating a large mass balance deficit. On October 16, 2020 the AAR of Gangotri Glacier was 23%.  More important the firn line indicates that the AAR is now consistently at ~25%. This will drive continued retreat and will accelerate the retreat. How far upglacier on Gangotri Glacier do you have to travel to reach the snowline?  On the central flow line 29-30 km along the 31-33 km length. The increase in temperature has led to a tendency for snowlines to rise in the post monsoon period and remain high into the winter season on other Himalayan glaciers such as West Rongbuk Glacier and around Mount Everest in 2019.

Central flowline for Gangotri Glacier, 32 km long, with 29.5 km in the ablation zone. Landsat image from 10-26-2020.

Mount Cayley Glacier, BC Loses 40% of Length 1985-2020

On By mspeltoIn British Columbia glacier retreat

Mount Cayley Glacier (MC) and Brandywine Glacier (B) near Callaghan Lake (CL) in 1985 and 2020 Landsat Images. Yellow arrow indicates 2020 terminus, red arrow indicates 1985 terminus location.

Mount Cayley Glacier and Brandywine Glacier drain the northeast flanks of Mount Cayley and Brandywine Mountain in the Coast Range,  25 km west of Whistler, BC.  Both glaciers drain in to Callaghan Creek, a tributary to Cheakamus Rover. Retreat of Mount Cayley Glacier has led to separation into two glaciers. Retreat of Brandywine Glacier has led to development of a proglacial lake. BC Hydro operates the 157 MW Cheakamus Generating Station with a tunnel and two penstocks carrying the water 11 kilometres from Daisy Lake Reservoir  to the Cheakamus GS. The Cheakamus River has substantial salmon populations including Pink, Coho, Steelhead and Chum. For Chum BC Hydro maintains an annual escapement and spawning survey.  The main run for Chum is in the fall from Oct. 15 to early December, with most years seeing more than 100,000 adult Chum heading upstream to spawn (Middleton et al 2019). This is a 4% survival rate from the typical salmon fry population that exceeds 2.5 million (Middleton et al 2019). Here we examine Landsat imagery to indicate the glacier change from 1985-2020.

In 1985 Mount Cayley Glacier had two branches that merged and terminated in a proglacial lake at  1520 m. The east arm flowed north from the west ridge of Brandywine Peak and the west branch drained the east side of Mount Cayley.  The west arm was 3.75  km long and the east branch 1.8 km long. Brandywine Glacier was 1.2 km long terminating at 1575 m. By 1993 the two arms of the Cayley Glacier had separated. The snowline was particularly high with less than 10% of each glacier retaining small snowpatches above 2000 m.  The end of winter in 2015 a UBC Ski trip  across this area illustrates how beatiful it is and how snowy. Depsite this snow covered look, the snowpack in 2015 was low and near the end of a warm summer the snowline was again above 2000 m. In 2017 the proglacial lake in front of Brandywine Glacier is 300 m long.  The snowline is lower at 1850 m. In 2020 Brandywine Glacier  continues to terminate in the small proglacial lake and has retreated 400 m during the 1985-2020 period. The east arm and west arm of Cayley Glacier have retreated  950 m and 1400 m respectively in this 35 year interval. In both case this is 40% of the entire length of the glacier lost. The glacier now terminates at 1720 m.

In 2020 the snowline was  1900-1950 m.  The continued limited area of the accumulation zone is driving mass balance losses and retreat.  Across this region Menounos et al (2018) identified a mass loss for glaciers in this region of ~0.5 m year from 2000-2018.  This has driven retreat of small and large glaciers such as Franklin Glacier, Bridge Glacier and Stave Glacier. In 2015 the snowline was the highest of the last 37 years in the North Cascades, WA a short distance south (Pelto, 2018).

Mount Cayley Glacier (MC) and Brandywine Glacier (B) near Callaghan Lake (CL) in 1993 and 2017 Landsat Images. Yellow arrow indicates 2020 terminus, red arrow indicates 1985 terminus location.

Mount Cayley-Powder Mountain Icecap in 2015 illustrating lack of retained snowcover in late August. Purple dots indicate snowline above Mount Cayley Glacier. MC=Mount Cayley Glacier, B=Brandywine Glacier

Canadian National Atlas map of region indicating flow direction of Mount Cayley and Brandywine Gacier.

Baqupu Glacier, China Merging Supraglacial Lakes 1998-2020

On By mspeltoIn Himalaya glacier retreat

Baqupu Glacier in Landsat images from 1998 and 2020 indicating the expansion of supraglacial lakes in the terminus zone.  Purples dots indicate the snowline in October of each year.

Baqupu Glacier is in the Poiqu River watershed in southern Tibet, China.  The Poiqu River becomes the Bhote Koshi as it crosses into Nepal before joining the Sun Koshi River. The terminus of the glacier extending from 4500-4800 m is debris covered. An icefall extends from 4800-5300 m, above which the accumulation zone extends up to 5900 m. Shrestha et al (2010) examined the risk of a glacier lake outburst flood in the Sun Koshi basin from a Lumichimi Lake further north in the Poiqu Basin.  They identified the potential for damage to the  45 MW Bhote Koshi Hydropower Plant.  A  July 2016 GLOF in the basin did in fact severely damage the Bhote Koshi Hydropower Plant. In a 2020 ICIMOD report (Bajracharya et al 2020) inventory of glacial lakes and potentially dangerous ones in the Koshi, Gandaki and Karnali Basin’s was updated. In the Sun Koshi Basin they mapped 181 lakes with an area of over 0.02 km2 with four being potentially dangerous lakes. The developing Baqupu Lake is not listed as potentially dangerous.

In 1998 Baqupu Glacier features a 0.03 km2 network of small supraglacial ponds at its surface at ~4500 m.  The snowline is near the top of the icefall at 5200 m in October.  By 2000 some evident expansion of the ponds is evident.  The snowline in October is again near the top of the icefall at 5200 m.  By 2018 there are four substantial ponds that have nearly coalesced. In 2019 the ponds have coalesced into two lakes.  The snowline is just above the icefall at 5300 m.  In 2020 the supraglacial lake system has an area of 0.24 km2.  Average area of  glacial lakes in basin is 0.12 km2 (Bajracharya et al 2020). The snowline is above the icefall at ~5400 m.  The persistent equilibrium line above the icefall during this period is reducing the flux through the icefall to the debris covered tongue.  The tongue is increasingly stagnant and the thinning will lead to continued lake expansion into what will be a proglacial lake.  This expansion is similar to that on Rongbuk Glacier, while other nearby lakes have had expanding proglacial lakes, Drogpa Nagtsang Glacier and Yanong Glacier.

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Baqupu Glacier in Landsat images from 2000 and 2018 indicating the expansion of supraglacial lakes in the terminus zone.  Purples dots indicate the snowline in October of each year.

Baqupu Glacier in Digital Globe image from 2019. A=Accumulation zone; D=Debris cover, I=Icefall, S=Supraglacial lake. 

Tungnafellsjökull, Iceland Recession and Thinning 1999-2020

On By mspeltoIn iceland glacier retreat

Tungnafellsjökull Ice Cap in 1999 and 2020 Landsat images indicating  terminus changes at three northern outlets, red arrows, and at four locations of bedrock exposure.

Tungnafellsjökull Ice Cap is a ~32km2 ice cap located between Vatnajökull and Hofsjökull.  Gunnlaugsson (2016) reported on the mass balance changes of the Tungnafellsjökull Ice Cap and found it had lost 20 of its volume and 16% of its area from 1960-2013.  The ice cap was essentially in balance from 1960-1986 and had a slight mass balance loss from 1986-1995.  Almost all of the loss has been since 1995. Belart et al (2020) report on losses from 14 smaller glacier in Iceland including Tungnafellsjökull and found signficant increase in mass loss from a near equilibrium 0.07 m/year from 1960-1994 to -1.20 m/year from 1995-2010. Here we examine the impact of the 25 years of sustained mass loss on Tungnafellsjökull using Landsat images.

In 1999 the transient snow line in August is at ~1200 m.  Point A,B and D indicate bedrock knobs amidst the ice cap and Point C a bedrock ridge that the ice cap flows over near Point C.  The three northern outlets terminate at the red arrows. From east to west they are Nordur Tungnafellsjökull, Innri Hagajökull and Fremri Hagajökull. In 2000 the transient snowline in August is again at ~1200 m. In 2014 the snowline was above 1500 m laving the ice cap without any retained snowpack from the previous winter.  The area of exposed firn encompasses 40% of the ice cap indicating the size of the accumulation zone in the several years prior to 2014. By 2016 the ice cap no longer flows over the ridge near Point C.  The transient snowline is at ~1400 m. In 2020 the transient snowline is at ~1350 m.  The bedrock knob at Point B is no longer surrounded by the ice cap. The bedrock at Point A and D have expanded.  The retreat from 1999-2020 is most significant at the three northern outlet glaciers, where Gunnlaugsson (2016)  indicated thinning was greatest. The retreat has been 200 m at Nordur Tungnafellsjökull,  600 m at Innri Hagajökull and  500 m at Fremri Hagajökull.

With an accumulation area covering approximately 40% of the ice cap, mass balance losses will continue and the ice cap will continue to retreat.  Retreat has been the consistent response of more than 90% of  Iceland glaciers since 2000 (Iceland Glaciological Society), such as at Norðurjökull.

Tungnafellsjökull Ice Cap in 2000 and 2016 Landsat images indicating  terminus changes at three northern outlets, red arrows, and at four locations of bedrock exposure.

Landsat image in August 2014 indicating the lack of retained snowcover.  The glacier surface is bare ice blue-gray and exposed firn indicated by the zone inside of the yellow dots.

Whiting River Headwater Glacier, British Columbia Separates into Four

On By mspeltoIn British Columbia glacier retreat3 Comments

Whiting River headwaters glaciers in 1984 and 2020 Landsat images.  The red arrows indicate 1984 terminus positions, yellow arrow the 2020 terminus locations, pink arrows locations of glacier detachment and purple dots the snowline.

In Northwest British Columbia on the northeast side of the Stikine Icefield the Whiting Rver drains a series of glaciers, many unnamed.  Here we are focusing on a pair of glaciers just west of Whiting Lake the headwater of Whiting River, which is on the east margin of the Landsat images from 1984-2020. Glacier mass loss in the region has been extensive leading to substantial glacier recession. Melkonian et al (2016) dentified a mass loss for glaciers for Stikine Icefield of ~0.6 m year from 2000-2013 which is driving retreat.

In 1984 the four branches of the westernmost glacier: west (W), main (M), south (S) and east (E) join together at ~900 m and the glacier flows downvalley to approximately 2 km to an elevation of 700 m.  The snowline is at 1250 m on the main branch. By 1999 the east branch has separated both from the south branch but also from the higher icefield at arrow #4. The snowline of the main branch is at 1300 m. By 2018 the west glacier has separated from the main branch at arrow #1, the south branch has also separated from the main branch near arrow #3. The four former tributaries are all separated.  The snowline in 2018 is the highest observed at 1550 m with a very limited accumulation area less than 10%, this year was a record high for the previous 70 years at nearby Taku Glacier. By 2020 the main branch has retreated 2300 m since 1984.  At arrow #2 there is a further detachment occurring from the east side accumulation are to the main branch. The eastern Whiting River Glacier has retreated 1250 m in this same period.

The retreat here is substantial in terms of the overall glacier length, and illustrates detachment as also noted for Farragut River, Alaska near the southwest corner of the Stikine Icefield. The retreat is less than that observed for the large outlet glaciers of Stikine Icefield such as South Sawyer, Dawes and Great Glacier. Whiting River is a remote and wild river that is host to six salmon species.


Whiting River headwaters glaciers in 1999 and 2018 Landsat images.  The red arrows indicate 1984 terminus positions, yellow arrow the 2020 terminus locations, pink arrows locations of glacier detachment and purple dots the snowline.

Franklin Glacier, British Columbia Tributary Detachment and Retreat 1987-2020

On By mspeltoIn British Columbia glacier retreat

Franklin Glacier, British Columbia in 1987 and 2020 late summer Landsat images.  Red arrow is the 1987 terminus, yellow arrow the 2020 terminus, and purple dots the snowline.   Point 1 is the junction with Dauntless Glacier, Point 2 is the junction with an unnamed glacier, Point 3 is where Whitetip Glacier joins the glacier, and Point 4 is where Jubilee Glacier previously joined.

Franklin Glacier is one of the largest glaciers in the British Columbia Coast Range extending 24 m southwest from the summit region of Mount Waddington. VanLooy and Forster (2008) observed that of the outlet glaciers from the five large icefields in this region Franklin Glacier had the greatest retreat from 1927-1974 of 4100 m. Mood and Smith (2015) note this glacier has had many Holocene advances with the mid-19th to early 20th century advance reaching its maximum Holocene extent. Here we examine late summer Landsat images from 1987-2020 to identify the ongoing response of this glacier to climate change.

In 1987 the Dauntless Glacier (Point 1) is a tributary joining the glacier at 1300 m.  The Whitetip Glacier joins the main glacier adjacent to (Point 3) averages 1900 m. The glacier separates into two main tributaries at 1800 m, with the snowline in 1987 being at m.  In 1995 the glacier retreat from the 1987 position, red arrow is evident, the snowline is at  1950 m. By 2000 the glacier has retreated ~900 m in the previous 13 years, the snowline is at  1900 m. In 2014 Dauntless Glacier (Point 1) has separated from Franklin Glacier.  The snowline  in 2014 is at 2050 m.  In 2017 the snowline is at 2100 m.  The trimline on the north side of the main trunk of the glacier between Point 3 and Point 4 that illustrates thinning is quite apparent and illustrates reduced thinning with distance upglacier.  There is a low surface slope of the glacier upglacier of Point 4 to Point 1 which hints at the potential of a basin where a proglacial lake could form.  In 2019 the snowline is at 2100 m.  By 2020 the glacier has retreated 2700 m from the 1987 position, the rate of  ~120 m/year is an increase from the 20th century rate after 1927. The unnamed tributary at Point 2 is detached from the main glacier. The snowline is at 2050 m in early September, 2020 dropping to 1700 m at the end of September. The high persistent snowlines averaging ~2100 m since 2014 indicate continued mass loss and increased retreat, this is also higher than the 1900 m ELA reported by VanLooy and Forster (2008). 

Menounos et al (2018) identified a mass loss for glaciers in this region of ~0.5 m year from 2000-2018 which is driving retreat.  The retreat rate during this period is slightly less than the 130 m/year at Bridge Glacier,or Klinaklini Glacier, and slightly more than at Bishop Glacier and Klippi Glacier.  The retreat has been more consistent, likely due to the fact there has been no proglacial lake at the terminus during this period. Franklin Glacier begins at an elevation of 3300 m, this results in the glacier continuing to have a significant accumulation zone in todays climate.

Franklin Glacier, British Columbia in 1995 and 2017 late summer Landsat images.  Red arrow is the 1987 terminus, yellow arrow the 2020 terminus, and purple dots the snowline.   Point 1 is the junction with Dauntless Glacier, Point 2 is the junction with an unnamed glacier, Point 3 is where Whitetip Glacier joins the glacier, and Point 4 is where Jubilee Glacier previously joined.

 

Franklin Glacier, British Columbia in 2000 and 2014 late summer Landsat images.  Red arrow is the 1987 terminus, yellow arrow the 2020 terminus, and purple dots the snowline.   Point 1 is the junction with Dauntless Glacier, Point 2 is the junction with an unnamed glacier, Point 3 is where Whitetip Glacier joins the glacier, and Point 4 is where Jubilee Glacier previously joined.

Jiemayangzong Glacier, Tibet Retreat, Separation and Lake Expansion 1991-2020

On By mspeltoIn china glacier retreat, Himalaya glacier retreat

Jiemayangzong Glacier in 1991 and 2020 Landsat images.  The red arrow is the 1991 terminus location, yellow arrow is the 2020 terminus location and purple dots mark the snowline. Point A indicates a tributary that has disconnected, while bedrock expanded at Point B. 

Jiemayangzong Glacier drains east from 6200 m peaks along the Nepal-China border. The glacier ends in a lake- Jiemayangzong Tso. Ren et al (2016)  identify this as the headwaters of  the Yarlung Tsangpo (Zangbo), which becomes the Brahmaputra River. The Zangmu hydropower project was completed on the river in 2015, it is a 510 MW project. Here we examine Landsat and Google Earth imagery from the 1991-2014 period. This is a region where Li et al (2011) noted that increasing temperature during the 1961-2008 period, especially at altitude, led to the retreat of glaciers and expansion of glacial lakes in this region. Liu et al (2011) noted that this glacier’s area has decreased 5%, retreating 768m ( 21 m/year), leading to lake expansion of ~64% during the 1974-2010 period.

In 1991 the lake was 1.1 km long, the snowline was at 5500 m near the elevation where the northern tributary joined at Point A.  In 1998 the snowline was at 5600 m, the glacier had not retreated appreciably.  In 2017 tributary A no longer is connected to the main glacier, the snowline is at 5600 m and the lake has expanded to a length of 1.9 km.  In 2020 the snowline in mid-September, with the melt season still going, is at  5700 m. The glacier has retreated 1000 m from 1991-202o a rate of  ~33 m/year. The lake is now 2.1 km long and has an area of  1.3 km2.  The glacier has a wide stable moraine belt (M) and does not pose a GLOF threat. Immediately downstream of the lake is a 10 km2 braided valley/wetland area (W) as well that would mitigate any potential flood hazard. This glaciers retreat is similar to many others draining north into Tibet from the Himalayan crest, Chako Glacier, West Ganglung Glacierand Asejiaguo Glacier

Jiemayangzong Glacier in 1998 and 2017 Landsat images.  The red arrow is the 1991 terminus location, yellow arrow is the 2020 terminus location and purple dots mark the snowline. Point A indicates a tributary that has disconnected, while bedrock expanded at Point B. 

Jieayangzong Glacier (JG) in 2015 Digital Globe image indicating the expanding proglacial lake (JL), moraine belt (M) and large wetland (W)

Ellsworth Glacier, Alaska Calves Major Iceberg in 2020

On By mspeltoIn alaska glacier retreat2 Comments

Ellsworth Glacier in Landsat images from 2018, 2019 and 2020. Red arrow is the 2016 terminus location, yellow arrow is the 2020 termins location, pink arrow is the rift, purple dots is the snowline, iceberg is Point A. Glacier retreated 2.4 km, main iceberg 1 km2

Ellsworth Glacier is a valley glacier draining south from Sargent Icefield on the Kenai Peninsula in Alaska. Along with the Excelsior Glacier it has been the longest glacier of the icefield.  The glacier retreated into an expanding proglacial lake in the early 20th century (USGS-Molnia, 2008). The terminus in 2000 was reported to be  3.5 to 4.5 km from the 1908 position (USGS-Molnia, 2008).  In a previous post we examined Landsat images from 1989-2016 to identify the changes including a 500 m retreat on the east margin of the lake and a 3400 m retreat on the west margin.  It as noted that “this rapid lake expansion indicates that the lower 3 km of the glacier occupies a basin that will become a lake and that the tongue is partially afloat and given the narrowing thinning tongue is poised for collapse”.  Here we document that collapse with Landsat images from 2016-2020.

In 2016 the snowline is at 975 m, the lake has now extended 3 km along the western edge.  The terminus is just east of  a former tributary glacier, red arrow. The number of icebergs in 2016 indicates that significant ice calved during that year. The retreat of the eastern margin has been 500 m, with a 3.4 km retreat on the west margin.  The main tongue in the lower two kilometers is 800 m wide versus 1200 m wide in 1989.  In 2018 the snowline is at 1100 m, the terminus remains just west of a former tributary glacier.  There is a rift forming near the pink arrow, where an iceberg will eventually detach (A).  In late June of 2019 the rift has further developed, but the iceberg to be (A) has not detached.  By mid-August of 2019 the rift has nearly led to detachment of an iceberg (A), the snowline is at 1075 m.  In June of 2020 the iceberg has detached and there is a considerable melange of ice between the iceberg (A) and the main terminus.  By Sept. 11, 2020 the iceberg remains in much the same position.

The glacier has retreated 2.4 km since 2018, and now terminates at yellow arrow 1 km downglacier of the junction of the two main tributaries.  The iceberg has maintained an area of ~1 km2.  The snowline in 2020 is at 1125 m indicating another of mass balance loss for the glacier. The lake is now 7 km long and the lake area is ~7.5 km2 up from 5 km2 in 2016. The retreat of this glacier paralells that of its neighbor Excelsior Glacier that retreated 4.7 km from 1994-2018. This continues to be a developing lake district including Grewingk Glacier.

Ellsworth Glacier in Landsat images from 2016-2020. Red arrow is the 2016 terminus location, yellow arrow is the 2020 termins location, pink arrow is the rift, purple dots is the snowline, iceberg is Point A.

Ellsworth Glacier in 2019. Point A is future iceberg is, yellow arrow is 2020 terminus locations and pink arrow is rift.  Image from Johnstone Adventure Lodge.

Leningradskiy Ice Cap Snowcover Vanishes in 2020 More Thinning, Svernaya Zemlya

On By mspeltoIn glacier climate change, russia glacier retreat

Leningradskiy Ice Cap  north to south strip in 2000 and 2020 Landsat images illustrating thinning leading to separation of parts of the ice cap at Point 1 and 4 and expansion of bedrock leading to merging bedrock regions at Point 1 and 2. R=snow/firnpack saturated with meltwater and consequent potential refreezing. S=superimposed ice development from surface refreezing.

Leningradskiy Ice Cap is oriented east to west across Bolshevik Island in the Svernaya Zemlya Archipelago of the Russian Arctic. Annual snowfall on the ice caps is limited ~0.4-0.5 m (Sharov and Tyukevina, 2010).  During the brief summer melt season from June-late August, much of the melt is refrozen within the snow/firnpack or as superimposed ice (Bassford et al 2006).  The low snowpack makes the glaciers vulnerable to warm summer conditions. The summer of 2020 has been remarkably warm in the Russian High Arctic leading to high melt rates and surface mass balance loss as shown by Xavier Fettweise MAR model. Here we examine Landsat images from 2000 to 2020 to identify a pattern of thinning on the northern margin of the ice cap.

In 2000 the glacier has a well established glacier runoff stream at yellow arrow. Point 1 is a nunatak amidst a peripheral segment of the ice cap. Point 2 is an area of bedrock separated by a narrow section of ice cap from adjacent bedrock. Point 3 and 4 are locations where the ice cap is thick enough to spillover in to an adjacent basin.  There is little visible snowpack on the ice cap, but a significant area of azure blue indicates snow/firnpack (R) that is saturated with meltwater, some of which will refreeze. There are zones of superimposed ice development(S)  where meltwater is refreezing on top of the cold surface ice. In 2018 there an area of unsaturated snowpack, white area, and saturated snow/firnpack (R) azure blue and areas of superimposed ice development (S).

On August 3, 2020 the ice cap has lost its snowcover with limited areas of firn, limiting the ability of meltwater to refreeze except on the surface as superimposed ice (S).  The lack of snow/firnpack at the surface will lead to a more negative balance as meltwater is not retained. At Point 1 this peripheral glacier area has been cutoff from the main ice cap as thinning has exposed more of the encircling ridge.  At Point 2 bedrock areas have expanded and merged together. At Point 3 there is some spillover still but thinning has led to a reduction and consequent retreat and thinning of this terminus. At Point 4 the ice cap no longer spillovers into the adjacent basin due to thinning. Each location indicates significant thinning that is hard to recover given the slow flow and limited accumulation on these glaciers. On Aug. 22 2020 the surface of the ice cap is frozen, leading to a whiter surface.

The lack of retained snowcover in 2020 was also seen at Hochstetter Ice Cap in Franz Josef Land.  In both cases the high summer temperatures led to more meltwater, and the lack of snowpack to retain leads to more escaping the system. Bassford et al (2006) describe this process “Intense surface melting in the accumulation zone during warm summers prevents the buildup of a thick firn layer by rapid transformation of firn to ice through refreezing and by removing
mass through runoff.”

Leningradskiy Ice Cap  north to south strip in 2018 and 2020 Landsat images illustrating changing distribution of melting (R) and superimposed ice development (S)

Khanasankoi Glacier, Russia Separation and Full Snowcover Loss

On By mspeltoIn Caucasus Glacier retreat1 Comment

Khasankoi Glacier in 1985, 1998, 2013 and 2020 Landsat imagery with Point 1-4 indicating locations where bedrock expansion is occurring with Point 1 and 3 separating the glacier into three parts. Note complete lack of snowcover on 8-26-2020.

Khasnakoi Glacier is a north facing slope glacier just south of Mount Elbrus that drains into the Kuban River. The Greater Caucasus contain approximately 2000 glaciers with a total area of ~1200 km2(Tielidze and Wheate, 2018).  Significant positive trends in annual and summer temperature from 1960-2014 have driven large overall glacier area loss, 0.53% per year, leading to the loss of over 300 glaciers (Tielidze and Wheate, 2018).  Here we examine Landsat images from 1985-2020 to identify key changes of the glacier.

In 1985 the glacier extended 4.6 km from east to west without interruption and featured three primary termini.  The glacier in 1985 has an accumulation area ratio (percent snowcovered) of 60%.  By 1998 there is limited retreat the glacier is still once continuous glacier and the accumulation area ratio is 40. By 2013 at Point 1 a bedrock ridge is emerging. At Point 2 a few outcrops of rock are evident emerging from under the thinning glacier.  The same is the case at Point 4. At Point 5 a new lake has developed at the margin.  The accumulation area ratio in 2013 is 25%.  In 2020 the accumulation area ratio is 0% snowcover.  A pair of ridges now bisect the glacier at Point 1 and Point 3. At Point 2 the rock outcrop has expanded into one large region.  At Point 4 a bedrock area has expanded at the head of the glacier.  At Point 5 retreat has left the newly formed lake of less than a decade ago isolated from the glacier.  This is not the first year of poor snowcover.

The mapped boundary of the glacier below provided by Levan Tieldze illustrates the glacier boundary in 1960, 1986 and 2014, illustrating a 29% decline in area. The loss of snowcover in 2020 is not the first summer when this has been observed in the Caucasus in 2017 Gora Gvandra did not retain snowcover. For Dzhikiugankez Glacier on the slopes of Mount Elbrus there has been a persistent low snowcover by end of summer since 2013. Tieldze (2019) explained the connection of climate to receding glaciers in the Caucasus using Tviberi Glacier in Georgia as an example.

Image from Levan Tieldze indicating the extent of the glacier in 1960 (red), 1986 (black) and 2014 (blue) on a 2016 SPOT image. There is still some connection above Point 1.

Map of the region from when Khasankoi Glacier was contiguous.