Tenderfoot Glacier, BC Fragmentation Accelerates

The glaciers of Tenderfoot Mountain in 1987 and 2022 Landsat images illustrating the decline in area and fragmentation. Tenderfoot Glacier B-C has lost more than 70% of its area and fragmented. Glacier D and E have experienced recession along their broad lower margins. Glacier F has disappeared

Tenderfoot Mountain has an array of glaciers on its flanks that have been rapidly losing area and fragmenting. One of these is Tenderfoot Glacier (B-C) that feeds into the Lardeau River in the Kootenay Lake Watershed. The glacier filled a north facing basin with an area of km² in the 1980’s topographic map of the area. This is a region where glaciers are struggling. Bevington and Menounos (2021) inventory of glaciers in Western Canada identified an increase rate of loss in this Southern Interior Range from 6.6 km²/year during the 1984-2010 interval to 22.1 km² per year from 2011-2020. They identified for the region that 14,329 glaciers larger than 0.05 km² existed in 1985, of these 13,270 glaciers larger than this threshold remained by 2020, this represents an 8% decline in the number of glaciers. They also identified an +300% increase in fragmentation of glaciers. Here we examine a sequence of Landsat images from 1987-2022 to illustrate the changes in the Tenderfoot Mountain region that and suppliment with a Sentinel 2022 false color satellite image.

In the National Topographic map the area of Tenderfoot Glacier had an area of 1.8 km² with the eastern tributary C feeding the main glacier (B). By 1987 the eastern Tributary (C) is nearly disconnected from Point B. There is a small cirque glacier at Point F. The glacier at Poit A is 0.6 km². In 1987 the combined area of the slope glaciers (D and E) is 5.0 km². In 1998 the Tenderfoot Glacier has not retained any snowcover illustrating why this glacier is more prone to both fragmentation and disappearing. By 2015 Point A glacier is beginning to fragment as well. By 2022 the Tenderfoot Glacier has three fragments with a combined area of 0.5 km², a 70% loss in area since 1987. The glacier at Point A has declined to 0.3 km². The glacier at Point F is gone. The combined area of Glacier D and E had declined to 3.4 km² a 30% decline. Tenderfoot Glacier did not retain any snowcover in 2021 or 2022, illustrating that it cannot survive even present climate. The Lardeau River is known Kokanee salmon . The Kokanee salmon population collapsed in Kootenay Lake after 2014 from 1 million to ~12,000 in 2017, rebounding somewhat to 90,000 in 2020 before declining again to 24,000 in fall 2021 (Nelson Daily, 2021).

Kokanee Glacier is another example of a struggling glacier in the region that Ben Pelto has monitored since 2014, too often with little snowcover by the end of summer, see below.

Tenderfoot Glacier in Canadian Topographic map and October 1, 2022 false color Sentinel image. Point B and C indicate two segments of the Tenderfoot Glacier that have now fragmented.

Kokanee Glacier in 2021 stripped bare of snowcover, with a relatively dirty surface (Ben Pelto-image).

King George Bay, Antarctica Glacier Retreat Expands Turret Point Oasis and Releases New Island

On January 2, 2023April 20, 2024 By mspeltoIn Antarctic Glacier retreat1 Comment

King George Bay Glacier retreat releases a new island (Point B) and expanded ice free oases in 1989 and 2022 Landat Images. Point A marks an area where the glacier had reached the coast until after 2005. Point B is the new island, Point C= new oasis, PI=Penguin Island, TP=Turret Point Oasis

King George Bay is on the southeast coast of King George Island. This coastline is comprised mainly of glacier margins ending in th sea, with limited ice free areas. The east end of the bay features the Turret Point Oasis, with Penguin Island just offshore. This oasis is a location used for breeding by Chinstrap and Adelie Penguins, and is a significant breeding area is for southern giant petrels, and Antarctic ‘blue-eyed’ shags. Elephant seals and fur seals are numerous in the latter part of the season (Korczak-Abshire,et al 2018). Here we examine Landsat images from 1989-2022 to identify changes in the glacier margin and the impact on this oasis and generation of a new island.

King George Bay Glacier retreat releases new island in Sentinel images from 2018 and 2022. Point A marks an area where the glacier had reached the coast until after 2005. Point B is the new island, Penguin Island=PI, TP=Turret Point, Point C is the new oasis.

In 1989 the Turret Point Oasis had an area of ~1 km². The King George Bay Glacier terminated on a bedrock rise at Point B. The glacier reached the coast between Turret Point and Point A. To the west there is no other ice free coastline, Point C. In 2005 the glacier was still terminating on the bedrock rise at Point B. The glacier is still reaching the coast between Point A and Turret Point and there is no ice free area near Point C. By 2018 there is a narrow finger of ice connecting to the Point B Bedrock rise and the shoreline between Turret Point and Point A is now free of glacier. there is a small strip of ice free coast near Point C. In 2022 the glacier has receded from the new island at Point B. The retreat at Point B is 950-1000 m since 1989, with a similar retreat across the broad front of the King George Bay Glacier to Point C. Glacier retreat from the shoreline near Point A has been 400 m. The Turret Point Oasis has expanded to 2 km², a doubling in size that expands oppportunity for greater diversity of flora and fauna. There is a new ~0.6 km² oasis that has formed at Point C. This is a narrow 200-400 m wide strip that is 1.7 km long. In the false color Sentinel images red indicates plant life for 12-24-2022 the Point C oasis does not have enough flora to be visible. This is in contrast to Turret Point and Penguin Island. The retreat here fits the pattern seen further west on King George Island on the Warsaw Ice Cap.

In 2016 the Arctwoski Station research survey found ~150 pairs of breeding Adlelie Penguins and 220 breeding pairs of southern giant petrels (Korczak-Abshire,et al 2018). In the Antarctic Treaty Turret Point oasis has specific visitor guidelines. The confluence of threats from climate change and human activity (Lee et al, 2022) makes Turret Point an important location to monitor. The retreat of glaciers opening up new potential breeding and feeding areas has been observed at Stephenson Lagoon on Heard Island and at Hindle Glacier on South Georgia.

Map illustrating locations bird and penguin species onTurret Point and Penguin Island from a UAV flight in 2016 from Korczak-Abshire,et al (2018)

King George Bay Glacier false color Sentinel image. Vegetation is evident on Turret Point=TP and Penguin Island=PI, but not at Poiunt C oasis.

Loss of Hinman Glacier, North Cascade Range 1958-2022

On December 29, 2022April 20, 2024 By mspeltoIn climate change glacier retreat, North Cascade Glaciers11 Comments

Himan Glacier in 1958 USGS map and in 2022 Sentinel 2 False Color image. The three ice masses with an area greater than 0.01 km² are indicated.

Hinman Glacier had descended the northwest flank of Mount Hinman in the North Cascades, Washington and based on 1958 aerial photographs, Hinman Glacier the USGS had listed this as the largest glacier in the North Cascades south of Glacier Peak with an area of 1.3 km² (Post el al 1971). In 2022 the glacier is gone with the largest relict fragment of ice at 0.04 km². This is the story of this glaciers demise that as documented by the North Cascade Glacier Climate Project, that for 40 years has observed in the field the response of glaciers to climate change.

Hinman Glacier in 1988 with 4 distinct ice masses.

In the 1960’s the glacier extended from the ridge top of Mount Hinman at 2250 m to the bottom of the valley at 1675 m. In 1988, Hinman Glacier from the west was a group of four separated ice masses that we surveyed. The amount of blue exposed that year indicates the glacier lacked a consistent accumumulation zone. This is indicative of a glacier that cannot survive (Pelto, 2010). In 1992 we mapped the largest of these remaining ice masses at 0.12 km², this was another year with only pockets of blue ice left. In 1998 the glacier has a few areas of blue ice are seen, the glacier was 20% of its mapped size 0.25 km².

In 2005 we observed how thin the ice was including being able to see rock at the bottom of several crevasses (see below). In 2006, from a Google Earth image,at this point the glacier is no longer detectable under the snowcover that persisted that summer, note the map outline and the gorgeous new “Hinman” Lake The new lake is 1 km long. A 2009 view from the far end, north end of Lake Hinman up the valley and mountain side that was covered by the Hinman Glacier, now 90% gone. Each of the two larger ice masses from 1998 is now divided into at least two smaller portions. By 2022 the ice fragments have further diminished with the largest just 0.04 km2, less than 4% of its 1958 size. The tendency of this former glacier to be bare of snowcover by late August in many years, is what led to the rapid loss. This same story is playing out on Foss Glacier on the other side of the ridge, though not as quickly.

Hinman Glacier thin sections of ice fragmenting in 2005.

The loss of glacier area of this glacier and in the Skykomish River Basin has impacted summer runoff in the Skykomish River watershed. From 1958-2009 glacier area declined from 3.8 km² to 2.1 km², (Pelto, 2011), and in 2022 has further diminished to 1.7 km², a 55% reduction. We have monitored all four major glaciers in the basin Columbia, Foss, Hinman and Lynch Glacier, the primary glaciers in the basin, declined in area by 25%, 70%, 95% and 40% respectively since 1958. Despite 15% higher ablation rates during the 1985-2022 period, the 55% reduction in glacier area led to a 40-50% reduction in glacier runoff between 1958 and 2022. The impact on the Skykomish River is evident.

Glacier runoff on Hinman Glacier heading the Skykomish River. Streams like this used to drain across the glacier all summer long. Now they no longer exist to feed the Skykomish in late summer.

A key threshold of in-stream flow levels considered insufficient to maintain short term survival of fish stocks is below 10% of the mean annual flow (Tennant, 1976). For the Skykomish River 10% of mean annual flow is 14 m³s^-1. In the Skykomish River from 1958-2021 there have been 363 melt season days with discharge below 14 m³s^-1. Of these only three occurred before 1985, and 67% have occurred since 2003. The loss of 55% of the glacier runoff is a key reason for the onset of critical low flow days. Of more concern for aquatic life is the occurrence of extended periods of low flow (Tennant, 1976). From 1929-2021 in the Skykomish River basin there have been 12 years where streamflow dropped below 14 m³s^-1 for 10 consecutive days during the melt season, 1986, 1987, 1992, 1998, 2003, 2005, 2006, 2007, 2015, 2017, 2019, 2021 and 2022. Precipitation has not declined during this interval, hence earlier snowmelt, reduced glacier runoff and greater evapotranspiration must be causing the increase in late summer low flow periods.

In 2022 a cool start to summer allowed snowpack to persist in the basin into August. Runoff was strong from Columbia Glacier on Aug.1 as we forded the outlet stream, see below. By September glaciers represented the main area of melt. An extended warm period extending into October led to persistent low flow conditions, below 495 cfs (14 m³/sec), from Sept 9.-Oct. 20.

The former Himan Glacier from the new”Hinman” Lake that has formed since 1958 with glacier retreat, 3 small ice patches remain in this 2009 view.

Hinman Glacier basin in 2006 Google Earth view, with “Hinman Lake”.

Himan Basin in Open Elevation map and in 2022 Sentinel 2 False Color image.

Streamflow and temperature in the Skykomish River at the USGS site at Gold Bar. Period of low flow begins after flow drops below ~500 CFS.

(https://waterdata.usgs.gov/monitoring-location/12134500/)

Fording headwaters of North Fork Skykomish, which is the runoff from Columbia Glacier, on 8-1-2022.

Lekhziri Glacier, Georgia Retreat Leads to Separation 1996-2022

On December 20, 2022April 20, 2024 By mspeltoIn Caucasus Glacier retreat1 Comment

Lekhrziri Glacier in 1996 and 2022 Landsat images illustrating the retreat and separation of the three tributaries central (Lc), eastern (Le) and western (Lw). Red arrow indicates 1996 terminus and yellow arrows the 2022 terminus locations

Lekhrziri Glacier has been the largest glacier in Georgia, and was until 2011 a compound glacier comprised of three tributaries joining a short distance from the terminus (Tielidze et al 2016). Tielidze et al (2015) observed in 2011 that the central tributary separated from the east and west tributary that year at the headwaters of the Mestiachala River Basin. From 2000-2020 Lekhziri Glacier experienced the largest retreat, of 1395 m, of 16 large Caucasus glaciers examined by (Tielidze et al 2022). Here we examine Landsat and Sentinel imagery from 1996-2022 to illustrate the changing nature of this glacier.

In 1996 the three tributaries joined at 2300 m and then flowed jointly south for 1 km to the terminus, red arrow on Landsat image. The August snowline is at 3300 m. By 2013 the central glacier has visibly separated by 500 m from the other tributaries. The primary terminus has had a retreat of ~500 m since 1996. The August snowline is at 3400 m in 2013. In 2022 additional retreat as separated the east and west tributaries, with an evident river emanating from each tributary, yellow arrows, feeding into the Mestiachala River. The central tributary terminates 800 m from the former junction. The retreat of the east tributary has been 1.3 km since 1996 and the west tributary 1.25 km since 1996. There is also a small lake that is evident, green arrow, in 2022 that will fill in with sediment. The snowline at the end of August 2022 is at 3450 m. The persistent high snowlines due to warm melt season conditions has led to ongoing mass loss that will lead to continued declines in the Lekhziri Glacier system. This is one example of the widespread retreat of glaciers in the region chronicled by Levan Tielidze. The high snowlines of 2017 and 2022 have been noted for Gora Gvandra glaciers and Zeno Svaneti glaciers.

Lekhrziri Glacier in 2013 Landsat image illustrating the retreat and separation of the three tributaries central (Lc), eastern (Le) and western (Lw). Red arrow indicates 2013 terminus and purple dots the snowline.

Lekhrziri Glacier in 2022 Sentinel image illustrating the retreat and separation of the three tributaries central (Lc), eastern (Le) and western (Lw). Yellow arrows the 2022 terminus locations aand green arrows the small lake at headwaters of Mestiachala River Basin.

Zemo Svaneti Glaciers, Georgia Not Poised for Survival

On December 10, 2022April 20, 2024 By mspeltoIn Caucasus Glacier retreat1 Comment

Ladevali (L), Tsaigmili (T), Baki (B), and Cherinda Glacier (C) in Sentinel false color image from August 30, 2022. Illustrating that each has 10% or less of the glacier surface retaining snowcover.

Several glaciers at the headwaters of the Doira River in the Zemo Svaneti Planned National Park in the Georgian Caucasus have been stripped of snowpack during recent summers. A glacier without a zone a persistent snowcover throughout the year has no accumulation zone and cannot survive (Pelto, 2010). Here we examine Ladevali, Tsaigmili, Baki and Cherinda Glaciers during August of 2016, 2018, 2020 and 2022 using Sentinel imagery. Tielidze and Wheate (2018) completed an inventory of Caucasus glaciers documenting the 1986 glacier surface area at 1482 square kilometers decreasing to 1193 square kilometers by 2014, a 20% decline in this 28 year period. Tielidze et al ( 2022) update this inventory identifying a 23% decline in area from 2000 to 2020, greater than 1% per year.

In 1998 ther Ladvali and Tsaigmili Glacier nearly join at the terminus. Baki Glacier spans the entire upper basin and no lake is evident near Point B. Cherinda Glacier descends a bedrock step to form a lower section. In mid-August of 2018 Baki Glacier has lost nearly all snowcover and a new lake has formed adjancent to Point B. Cherlinda Glacier has a fringe 15% along its upper margin and is no longer connected to lower relict ice below the bedrock step. Ladevali and Tsaigmili Glacier have snow cover above 3200 m covering 15-20% of the glacier and the termini are now separated by ~1 km. At the end of August in 2020 Baki Glacier is snow free. Cherinda has a fringe on its upper maring covering less than 10% of the glacier. Ladevali and Tsaigmili Glacier have snow cover above 3300 m covering ~5% of the glacier. At the end of August 2022 Baki Glacier is again snow free, while Cherinda has a fringe on its upper margin covering 10% of the Glacier. Ladevali and Tsaigmili Glacier have snow cover above 3250 m covering ~10% of the glacier. In 2022 the glaciers also exhibit a lack of retained firn from any recent year, illustrating a consistent lack of retained accumulation. This consistent minimal retained snowcover illustrates that the glaciers cannot survive current climate. A similar situation has been observed further east at Gora Gvandra. The mass balance in the region has continued to decline with a mean annual loss of ~-0.5 m/year from 2000-2019, (Tielidze et al 2022) with 2020-2022 likely even worse

Ladevali (L), Tsaigmili (T), Baki (B), and Cherinda Glacier (C) in Sentinel true color image from August 30, 2020. Illustrating that each has 10% or less of the glacier surface retaining snowcover.

Ladevali (L), Tsaigmili (T), Baki (B), and Cherinda Glacier (C) in Sentinel false color image from August 16, 2018. Illustrating that each has 20% or less of the glacier surface retaining snowcover with several weeks left in the melt season.

Ladevali (L), Tsaigmili (T), Baki (B), and Cherinda Glacier (C) in Landsat image from mid-August 1998. Ladvali and Tsaigmili nearly join in 1998. Baki Glacier expands across the entire basin and Cherlinda descends below a bedrock step.

North Annapurna Glacier, Nepal Retreat and Lake Development

On November 28, 2022April 20, 2024 By mspeltoIn Himalaya glacier retreat, nepal glacier retreat1 Comment

North Annapurna Glacier in August 2022 Sentinel image. A=North Annapurna Base Camp, I=icefall base, B= Prominent Knob, C=tributary that has separated by 2022. The green arrow marks the end of the active ice which is now 1.5 km upglacier of the terminus. Note Diki Cho (lake) is relatively free of icebergs that were plentiful in 2018.

North Annapurna Glacier drains the northeast side of Annapurna (8091 m). The North Annapurna climbers base camp (NABC) for the original ascent in 1950 was opened to trekking in 2020 via the new Maurice Herzog Trail. The NABC is located near the terminus of the North Annapurna Glacier, when first located there was no lake at the terminus of the glacier. Today glacier thinning and retreat has led to development of DikiCho. The glacier has also become stagnant in its lower reaches. Here we examine Landsat imagery from 1988-2022 to identify the long term changes, and Sentinel imagery from 2018-2022 along with trekking images from 2020-2021 to look at the lake development in details.

North Annapurna Glacier in 1988 and 2022 Landsat images. Yellow arrow indicates 2022 terminus location. A=North Annapurna Base Camp, I=icefall base, B= Prominent Knob, C=tributary that has separated.

In 1988 North Annapurna Glacier extended to the end of what has become Diki Cho (lake) and into the main north/south valley of the Miristi Khola. The tributary at Point C connects to the glacier above the icefall. The area of active blue ice extends 1.5 km beyond the icefall, including a series of ogives. The only evident change is the increase debris cover below the icefall. In 2001 the first sign of a lake at the terminus is evident and active blue ice extends beyond Point B. By 2018 Diki Cho has expanded to an area of 0.15 km² and has considerable stranded icebergs amidst the lake. The area of active ice ends just below Point B. By 2021 most of the ice amidst Diki Cho has melted. Tributary C no longer connects to the main glacier and the zone of blue ice extends just beyond the base of the icefall. The wam summer of 2022 led to further lake expansion particularly along the southern margin of the glacier, with an area of 0.27 km². The lower 1.5 km of the glacier is stagnant. North Annapurna Glacier has retreated 600 m from 1988-2022. The lower 1.5 km of the glacier is no longer being actively fed by the glacier and will be lost, though with thick debris cover this will not happen quickly. This section of the glacier also has a low surface gradient indicating that lake expansion will continue. The retreat here has been slower than at Lumding Glacier or Barun Glacier, but is increasing in the last decade.

North Annapurna Glacier in 1991 and 2022 Landsat images. Yellow arrow indicates 2021 terminus location and green arrow the end of the blue ice. A=North Annapurna Base Camp, I=icefall base, B= Prominent Knob, C=tributary that has separated.

North Annapurna Glacier in August 2018 Sentinel image. A=North Annapurna Base Camp, I=icefall base, B= Prominent Knob, C=tributary that has separated. The green arrow marks the end of the active ice which is now 1.5 km upglacier of the terminus. Note Diki Cho has many icebergs.

Annotated image of Diki Cho from near the North Annapurna Base Camp, image from Nepal Trek Hub.

North Annapurna Glacier in 2001 Landsat image. Yellow arrow indicates 2021 terminus location and green arrow the end of the blue ice. A=North Annapurna Base Camp, I=icefall base, B= Prominent Knob, C=tributary that is separating.

Suru Basin, Ladakh India Glaciers Bare of Snowcover in August 2022

On November 22, 2022April 20, 2024 By mspeltoIn glacier climate change, Himalaya glacier retreat, India glacier retreat

Suru Basin glaciers in 1998 and 2022 Landsat images. Red arrow marks the 1998 terminus location, yellow arrow the 2022 terminus location. S=Shafat Glacier, D=Dilung Glacier. Glacier 1-4 are unnamed glaciers that lost almost all snowcover in 2022.

Glaciers of the Suru Basin, draining the Ladakh Range, a drier region of the Himalaya, was significantly by the 2022 pre-monsoon and monsoon season warmth. Here we focus on a group of glaciers near Shafat and Dilung Glacier that lost snowcover in 2022. We also look at the retreat of Shafat and Dilung Glacier. Shafat Glacier occupies the northeast flank of Nun Kun Peak in Ladakh India and drains into the Suru valley. The main valley glacier has suffered from detached tributaries leading to terminus area stagnation (Pelto, 2021). Dilung Glacier retreat has led to an expanding proglacial lake. Shukla et al (2020) identified an increase in annual temperature has driven a 6% loss in regional glacier area and a 62% expansion in debris cover from 1971-2017. Here we compare Landsat imagery from 1998-2022 to identify this glaciers response to climate change.

In 1998 the terminus of Shafat Glacier was at the red arrow near a junction with a key tributary, with clean active ice reaching to the terminus. By 2022 the active ice is 2.5 km upglacier from this point at the yellow arrow, though there is stagnant debris covered ice below this point. Dilung Glacier in 1998 terminates in a 1.1 km long proglacial lake. By 2022 the glacier has retreated 900 m, resulting in a 2.0 km long lake. Rashid and Majeed (2018) indicate nearby Drang Drung Glacier has retreated 925 m since 1971, with a sharp increase after 2014.

For an alpine glacier to have a balanced annual budget it has to be 50-60 snowcovered at the end of the melt season. On Sept. 1, 2022 there are four glaciers 1-4 in this region that have 0-10% snowcover left. The snowcover is above 5300 m. This is illustrative of significant mass losses in 2022. On Dilung Glacier and Shafat Glacier the snowcover is ~20% and is confined to the regions above 5300 m. There is some cloudcover over the top of the Shafat Glacier in the 9-1-2022 Landsat image.

Suru Basin glaciers in September 1, 2022 Landsat image. Glacier 1-4 are unnamed glaciers that lost almost all snowcover in 2022. S=Shafat Glacier, D=Dilung Glacier. The snowline is above 5300 m.

Jiangpu and Daoge Glacier Retreat and Lake Expansion, China

On November 14, 2022April 20, 2024 By mspeltoIn china glacier retreat

Daoge and Jiangpu Glacier retreat and proglacial lake expansion in Landsat images from 1988 and 2022. Yellow arrow is the 2022 terminus location, red arrow the 1988 terminus location and purple dots the snowline.

The Jiangpu Glacier and Daoge Glacier are the second and third largest glaciers in the Nyainqentanglha East Range. They flow south in adjacent valleys that feed the Yi’ong Tsangpo, which joins the Parlung Zangbo. Draining north from the same mountains is Jiongla Glacier, which retreated 3200 m from 1988-2015. Qin ji et al (2018) noted glacier recession of 1.24% per year from 1999-2015 in this range, in response to rising annual air temperature. Here we examine satellite imagery from 1988, 2000, 2015 and 2022 to identify the changes in these glaciers.

In 1988 Daoge Glacier terminates in a proglacial lake at ~4000 m that is 1.3 km long. Jiangpu Glacier terminates at a moraine complex at ~3250 m. The snowline in 1988 is at 4600-4700 m. By 2000 there is limited retreat evident at both glaciers and the snowline is at 4500-4600 m. In 2015 the lake at the terminus of Daoge has expanded to 2.5 km, while there is still no lake at the terminus of Jiangpu, with the snowline at 4800 m. In 2022 the summer heat wave experienced by the region pushed the snowline up to 5100-5200 m on Aug. 11, 2022. The lake at the terminus of Daoge Glacier has expanded to 3.2 km in length. For Jiangpu Glaicer a 0.4 km² lake has formed at the terminus due to a landslide triggered by an earthquake swarm in 2020 (Sheth, 2020). Glacier retreat from 1988-2022 has been 1900 m at Daoge Glacier and 2050 m at Jiangpu Glacier.

The high snowline in recent years will continue the retreat of both glaciers, which both have stagnant terminus regions for ~3 km above the current terminus location. There is no slope change at Daoge Glacier indicating lake expansion is near and end. At Jiangpu Glacier the lake is not expanding upvalley, and appears likely to fill in with sediment. This is not surprising given this is not a erosional basin, but a shallow valley fill lake impounded by landslide sediments.

Daoge and Jiangpu Glacier retreat and proglacial lake expansion in Landsat images from 2000 and 2015. Red arrows the 1988 terminus location and purple dots the snowline.

Bara Shigri Glacier, India Separation of Tributaries

On November 7, 2022April 20, 2024 By mspeltoIn Himalaya glacier retreat, India glacier retreat

Bara Shigri Glacier in 1993 and 2022 Landsat images indicating the separation of a number of tributaries. Purple dots mark the snowline 1993=5050 m and 2022=5600 m.

Bara Shigri Glacier, India is in Chandra Valley of the Western Himalaya. Chand et al (2017) report on the behavior of the glacier from the Little Ice Age to 2014 noting a retreat of 255 m from 1992-2002 and 168 m from 2002-2014. This 26 km long glacier had an average snowline maximum elevation of 5340 m for the 2000-2014 period. The glacier has been fed by a number of significant tributaries feeding from the southwest, here labeled 1-9. The snowline has risen above 5400 m with increasing frequency resulting in a limited accumulation area as observed in Landsat images from 2002, 2016, 2020 and 2022.

In 1993 tributary 1, 3, 4, 5, 6, 8 and 9 feed the main stem, while tributary 2 does not reach the main stem and tributary 7 just meets it without apparent contribution. In 2002 the same tributaries continue to contribute ice to the main stem as in 1993. The snowline is much higher at 5400 m. In 2022 tributaries 1, 4 and 5 no longer contribute to the mainstem of the glacier, leaving Only tributaries 3, 6, 8 and 9 connecting. The snowline in 2020 averaged 5600 m as well, with higher snow levels on the southwest tributaries and a lower snowline on the northeast arm of the glacier.

The detachment of tributaries illustrates mass balance loss of these glaciers and consequence decrease in volume flux into Bara Shigri Glacier which will lead to continued retreat. Patel et al (2021) noted a mass loss rate of -0.59 m w.e. per year from 2013-2019 indicating the basin wide nature of mass loss. This mass loss is also leading to retreat of nearby Samudra Tapu Glacier.

Bara Shigri Glacier in 2002 Landsat image indicating the separation of a number of tributaries. Purple dots mark the snowline 1993=5050 m and 2022=5400 m.

Bara Shigri Glacier in 2020 Landsat image indicating the separation of a number of tributaries. Purple dots mark the snowline 1993=5050 m and 2022=5600 m.

Suiattle, White River, Whitechuck and Honeycomb Glaciers North Cascade Range Diminishing Rapidly

On October 28, 2022April 20, 2024 By mspeltoIn North Cascade Glaciers

USGS Map of the four glacier from 1984, with none of the seven lakes existing.

In 1988 we mapped four glaciers arrayed around the Kololo Peaks just south of Glacier Peak; Honeycomb and White River feeding into Wenatchee Lake watershed, while Whitechuck and Suiatlle fed into the Suiattle River watershed. They had a combined area of 9.2 km². The glaciers had not developed a series of proglacial terminus lakes at that time. We visited each glacier and completed observations in 1995 and 2002 illustrated the formation of six proglacial lakes, with one more developing after that, Lake #7. Further details and image for Whitechuck Glacier . In 2022 the glaciers have retreated away from each of these lakes that had not even begun to form in 1988. The combined area of the four glaciers in 2022 is 5.6 km², a 40% decrease in 34 years.

Whitechuck Glacier in 1988, with the North Branch and South Branch joined and terminating at Lake #5.

Whitechuck Glacier in 2002 with a detached glacier segment at Lake #5.

White River Glacier in 1988 with no lake yet formed at #3 or #4.

White River Glacier terminus with Lake #3 having formed, but still largely snowcovered in early August.

Honeycomb Glacier in 1995 with no lake #1 at the terminus yet.

Honeycomb Glacier in 2002 still in contact with Lake #1.

Kololo Peak glaciers in Sept. 9 2022 Sentinel image. H=Honeycomb, S=Suiattle, WC=Whitechuck, WR=White River, purple dots are the snowline and Point 1-7 proglacial lakes that formed after 1988 and are no longer in constact with glacier.

In 2022 we had the most extensive melting we have observed after September 1, with active significant melt extending to October 19. The result is striking in Sentinel images from Sept. 7 and Oct. 19 indicating the reduction in snowcovered area, the percentage of a glacier covered by snow is its accumulation area ratio (AAR). On September 9 the AAR of these glaciers was 45% diminishing to 10% by October 19. With negligible retained snowpack on Whitechuck and White River Glacier. Since 1988 Honeycomb Glacier has retreated 950 m, White River Glacier 475 m, Whitechuck Glacier 950 m and Suiattle Glacier 450 m.

Kololo Peak glaciers in Oct. 19, 2022 Sentinel image. H=Honeycomb, S=Suiattle, WC=Whitechuck, WR=White River, purple dots are the snowline and Point 1-7 proglacial lakes that formed after 1988 and are no longer in constact with glacier.

Icemantle Glacier, British Columbia Declinining Rapidly

On October 21, 2022April 20, 2024 By mspeltoIn British Columbia glacier retreat1 Comment

Icemantle Glacier in Landsat images from 2000-2022 illustrating the retreat exposing a new lake (Point A) and separation at Point D. Also the lack of snowcover in 2009, 2015 and 2022 indicative of mass balance loss that drives retreat.

Icemantle Glacier is on the north side of Greenmantle Peak just north of Snowcap Lake in the Lilloet River Basin of southwest British Columbia. Here we focus on the retreat and thinning of the glacier this century using Landsat imagery and then lack of snowcover extending into mid-October in 2022 using Sentinel images.

In 2000 the glacier extended across the basin where the new lake would soon form. The Landsat image from July 31, indicates near complete snowcover at the halfway point of themelt season. By 2009 a frining lake is evident between Point A and B. Snowcover is limited to the upper reaches above 2100 m. By 2015 the lake is evident and has numerous icebergs. Below Point B a bedrock knob is just emerging. At Point D the tributary is completing separation. In 2022 the glacier is receding from the lake basin. The bedrock knob below Point B in Landsat image and at Point A in Sentinel image has emerged. The snowline rises from 2000-2050 m in early September to 2100-2150 m by mid-October. At this point the glacier should have new snowcover, and not still be actively melting.

The lake has an area of 0.3 km2 and will not expand much more. The glacier has retreated 600 m this century and given the lack of consistent retained snowcover cannot survive current climate (Pelto, 2010). The thinning of this glacier has led to expansion and emergence of bedrock knobs at Point A-C. The retreat of this glacier fits the local pattern seen at nearby Stave Glacier. The surface darkening due to less snowcover and snowcover that has more light absorbing particles at its surfaces enhances melt. Forest fires do result in some darkening of the glacier surface (Orlove, 2020).

Icemantle Glacier in early September, when snow melt is usually largely offset by occassional new snowfall, and mid-October 2022 after a month of continue ablation reduced snowcover significantly. Notice the expansion and emergence of bedrock at Point A-C.

Brady Glacier Retreat Causes Ice Dammed Spur and Trick Lake Drawdown

On October 12, 2022April 20, 2024 By mspeltoIn alaska glacier retreat1 Comment

Brady Glacier terminus region in September 28, 2022 Sentinel image. Red dots indicate the 2016 margin. Point A marks the new isthmus exposed by falling lake water level. Point B-D are the expanded drainage channels.

Brady Glacier is a large Alaskan tidewater glacier in the Glacier Bay region that is beginning phase of substantial retreat that was forecast by Pelto et al (2013). The glacier has seven secondary termini in marginal ice dammed proglacial lakes. There was a consistent pattern in the change in position of the glacier margin at each of the lakes between 1948 and 2010. The rate of retreat of the glacier margin at all seven ice dammed lakes accelerated later during this period; the mean retreat rate was 13 m/a from 1948 to 2004 and 42 m/a from 2004 to 2010 (Pelto et al 2013). Lake area and calving fronts were measured for each lake: Spur, Abyss, North Deception, Bearhole, Oscar, and East Trick based on the September 2010 imagery, with earlier measurements from Capps et al (2010). Lake areas can increase as a result of Brady Glacier marginal retreat, and can decrease due to declines in surface water levels as previously ice-dammed conduits form to drain the lake (Pelto 2016). Here we examine the changes in area of Spur and Trick Lake from 2016-2022 during development of substantial marginal drainage channels. During this period the terminus of the glacier has retreated on average 175 m, with 300 m of retreat from its maximum position advance position.

Brady Glacier terminus region in September 29 2016 Sentinel image. Yellow dots indicate the 2022 margin. East and North Trick lakes are connected basins. Spur Lake still has an eastward extension.

Trick Lakes: In 1986 North and South Trick Lake were proglacial lakes in contact with the glacier. By 2016 the two lakes were no longer in contact with the glacier, water levels had fallen and a third lake East Trick Lake had formed. North Trick Lake and South Trick Lake are currently relatively stable moraine-dammed lakes. The more recently developed East Trick Lake is the current proglacial Trick Lake, a large glacier river exits this lake and parallels the glacier to the main Brady Glacier terminus. In 2016 this river was narrow and flowed beneath the glacier in several spots. By 2022 the channel has expanded to a width that seldom is less than 200 m, and is tranisitioning to an ice marginal lake. East Trick Lake has an area of 1.25 km² in 2016, expanding to 1.4 km² in 2019, before declining to 1.0 km² in 2022 with the lake separating into two parts by a narrow peninsula exposed by falling water levels. The water level decline resulting from a 200 m marginal retreat from 2016 to 2022 has led to a narrow isthmus running across the lake from the glacier to be exposed. At Point E below the trimlines from reduced water levels are evident.

Spur Lake: It is likely that retreat toward the main valley of the Brady Glacier will lead to increased water depths at Spur Lake. a marginal retreat of 600 m led to a lowering lake water level from 2010-2016. The lake had an area of 0.6 km2 in 2010, 0.5 km² in 2016, o.5 km² and 0.5 km² in 2022. The lake area decline due to falling water level has been matched by lake area increase due to marginal retreat of Brady Glacier. This marginal retreat has also opened a marginal channel along the east edge of the glacier, draining Spur Lake. This drainage has led the lake shoreline to migrate west. Marginal retreat has been ~100 m from 2016-2022. The marginal river on the east side of the glacier was narrow and occasionally went beneath the glacier in 2016. In 2022 the channel has expanded so that the upper 2.5 km and lower 1.5 km is more of a marginal lake.

North Deception Lake has been expanding as the glacier has retreated 600 m, 100m/year from 2016-2022 while maintaining its water level. At present there is not a marginal channel developed that can reduce the water level. How long until a channel opens?

In Alaska the glacial lakes have expanded in area by 58% from 1984-2018 (Field et al 2021), however the ice dammed lakes declined by 0.4%. The latter indicates the competing impacts of water level reduction due to glacier recession of ice dammed lakes, and the expansion due to retreat as well.

Brady Glacier terminus region in September 28, 2022 Sentinel image. Point A marks the new isthmus exposed by falling lake water level. Point B and D are the expanded drainage channels. Point E is where trimlines are evident.