Oriental Glacier in 1986 and 2021 Landsat imagery illustrating retreat from the island (I) and diminishing width and flow of tributaries at P0int A and B. A marginal lake has formed at Point M as the glaciers terminus section has thinned and narrowed.
Oriental Glacier terminates in an expanding proglacial Lago Oriental at the northeastern margin of the Southern Patagonia Icefield (SPI). The glacier had terminated on an island in this lake for several decades until 2019. In this region glaciers thinned ~0.5 m/year from 2000-2012 with Oriental Glacier thinning 0.5-1.0 m/a (Falaschi et al 2017).. Mouginot and Rignot (2014) identified a velocity peak at 1 km/year extending from the Cerro Azul (3018 m) eastward to the northward terminus bend. Oriental Glacier had a slower retreat than most SPI glaciers from 1870-2011 at 0.1-0.15 km/a, and the fastest rate from 2001-2011 Davies and Glasser (2012). Here we examine Landsat imagery from 1986 to 2021 to illustrate glacier changes and Sentinel imagery from 2020 and 2021 illustrating island separation and retreat acceleration.
In 1986 the glacier terminates on the island with a small proglacial outwash plain in front of the eastern tongue, marginal connection is 1.5 km long. Tributary A and B are both significant contributors to the terminus tongue. At Point M the glacier is 1.75 km wide. The surface slope of the lower 6 km of the glacier in from 1986-2002 is ~4-5%, this is a low surface slope, suggesting this section of the glacier occupies a basin, a continuatin of the current Lago Oriental. In 1998 there is little evident change. By 2002 the glacier connection to the island has a similar length, but the ice is thinner than in 1986. In 2015, tributary A and B are narrower, contributing less ice to the terminus region. The connection to the island is reduced to ~1 km, while the proglacial outwash plain is still similar in size. In January of 2019 the connection to the island is almost gone and the proglacial outwash plain is significantly reduced. The marginal lake is ~0.05 km2. By February of 2020 the connection to the island has been lost and the marginal lake has expanded to 0.1 km2. In 2021 the glacier has retreated 150 m from the island and a rift has formed that will lead to a signficant calving event ~0.125 km2, probably this summer. The marginal lake has expanded to 0.2 km2 . Tributary B has essentially separated from the main glacier in 2021.
Calluqueo Glacier retreat and Lucia Glacier retreat have been significantly larger; however, Oriental Glacier is poised for a rapid retreat and lake expansion. The lake basin likely extends at least 5 km from the present terminus. At that point Lago Oriental would be 9 km long.
Oriental Glacier terminus reach in 2019, 2020 and 2021 Sentinel 2 imagery illustrating retreat from the island (I) and expansion of the marginal lake at Point M. Note tributary B has essentially disconnected in 2021. A rift is forming at yellow arrow, poised for a calving event this summer.
Oriental Glacier in 2002 and 2015 Landsat imagery illustrating connection remaining to the island (I). A small marginal lake has formed at Point M as the glaciers terminus section has thinned and narrowed.
Oriental Glacier in 1998 Landsat image and topographic map of area. Elevation contours indicates low slope of termius reach from 600 m to terminus. Blue arrows indicate glacier flow.
Hindle Fjord opening comparison in 2009, 2015 and 2021 Landsat images. Point A is the northern tributary, Point B the middle tributary, Point C separates the eastern and western tributary and Point D is Ross Glacier.
Hindle Glacier enters Royal Bay on the east coast of South Georgia Island. The British Antarctic Survey (BAS) has been the examining glacier change on South Georgia Island, Cook et al (2010) noted a pattern island wide with many calving glaciers having the fastest retreat. Alison Cook (BAS) identified that 212 of the Peninsula’s 244 marine glaciers have retreated over the past 50 years and rates of retreat are increasing. In 2017 we examined Landsat imagery from 1989 to 2017 to identify the rapid retreat rate of Hindle Glacier. NASA Earth piggy backed on this assessment, with excellent imagery, since the retreat rate has increased. Here we focus on the formation of the fjord from 2009-2021.
For Ross-Hindle Glaicer in 1989 the glaciers joined 2.5 km from the terminus spanning Royal Bay with a 3.2 km wide calving front. By 2001 the glacier front had retreated 800 m, but was still a single joined calving front. By 2009 the glaciers had separated due to an additional retreat of 1.4 km. The Hindle Glacier front was now retreating south up opening a new separate fjord from Ross Glacier. The calving front in 2009 was 1.6 km wide. By 2015 a 1.6 km retreat led to the separation of Hindle from the northern tributary, Point A. From 2015 to 2019 the main terminus retreated another 2.1 km, passed the middle tributary at Point B, to a prominent rock knob, Point C, separating the two main tributaries of the glacier with total retreat of 6.1 km in 30 years, an exceptional rate of over 200 m/year. The western tributary is at the head of the fjord and no longer calves significantly, while the eastern tributary has another 1 km to an increase in slopes that likely is close to head of the fjord. The new fjord is 4.5 km long and averages 1.1 km in width and has an area of 5.5 km2. The northern tributary near Point A is also still calving and retreating.
This embayment opens up new areas for Gentoo Penguins and Elephant Seals to occupy. There are current colonies in Royal Bay and like at Moraine fjord, these two species are early colonizers of deglaciated terrain (see map below from BAS). In particular the beaches adjacent to the northern tributary, just north of Point B and northwest of Point A are wave protected and low slope. Levy et al (2016) discuss that the southern Gentoo Penguins tend to remain within the same archipelago year around. They examined DNA from 39 Gentoo at Bird Island, adjacent to South Georgia, and found none were migrants.
Hindle Fjord in 2020 and 2021 Sentinel images indicating ongoing retreat at Point A and C, with a significant sediment plume from Point B in December 2020. Point A is the northern tributary, Point B the middle tributary, Point C separates the eastern and western tributary and Point D is Ross Glacier.
Hindle Glacier comparison in 2001, 2017 and 2019 Landsat images. The red arrow is the 2001 glacier terminus. Point A is the northern tributary, Point B the middle tributary, Point C separates the eastern and western tributary and Point D is Ross Glacier.
British Anatarctic Survey map of Royal Bay area showing Elephant Seal beaches (yellow X) and Gentoo Penguin colonies (purple dots).
Laguna de los Tempanos full on February 9, 2021 and drained on December 6, 2021 in Sentinel 2 images. Point A marks the western margin when full. Point C marks the western margin when drained.
Steffen Glacier is the south flowing glacier from the 4000 km2 Northern Patagonia Icefield (NPI). Several key research papers have reported on the spectacular retreat of this glacier in recent years. Glasser et al (2016) reported that Steffen Glacier proglacial lake area expanded from 12.1 km2 to 20.6 km2 from 1987 to 2015, due tin part to a 100 m snowline rise. noted to have risen ~100 m. Dussaillant et al (2018) determined the annual mass loss of NPI at ~-1 m/year for the 2000-2012 period, with Steffen Glacier at -1.2-1.6 m/year. Millan et al (2019) indicate the area of tributary glacier convergence near the northwest terminus and above the glacier is 700 m thick, and that the glacier has been retreating along an area where the glacier bed is below sea level, though the terminus now is close to sea level. Steffen Glacier retreat from 1987-2019 was 4.4 km, ~137 m/year (Pelto, 2019). Aniya et al (2020) reported on 19 glacier drainage events from 1974-2020, with most occurring in late summer or early Fall. They noted the largest in 2016 and 2017 were the first to expose much of the lake bottom.
There are two large ice dammed proglacial lakes on the west side of the glacier. Laguna de Los Tempanos is the southern one 6 km upglacier of the current terminus and 11 km upglacier of the 1987 terminus position. Here we utilize Landsat and Sentinel imagery to examine the evolution of the lake from 1987-2021, Including the 2021 drainage event.
Laguna de los Tempanos in Landsat images from 1987, 1999, 2012 and 2019. Yellow arrow is western extent of the lake in 1987 and 1999, while Point A is the western extent in 2012 and 2019.
In 1987 the area of the lake is 5.2 km2 extending west past point A to the yellow arrow. In 1999 the water level is lower leading to a peninsula developing at Point A, with a lake area of 5.0 km2. By 2012 the water level had dropped further and the west margin of the lake was now at Point A and the lake area was 4.8 km2. The filled size remained unchanged for most of the 2012-2021 period, though there was large drainage events in 2016 and 2017 the lake rapidly refilled.
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On November 17, 2016 the lake is full, but it is drained on April 16, 2017 with evident icebergs on the bottom, the drainage event occurred on March 30/31 2017 (Aniya et al 2020) .
By January 21, 2018 the lake is again full and is full again on December 7, 2018 in Sentinel 2 images.
The lake is full on March 27, 2019 and on Feb. 20, 2020 in Sentinel 2 images.
On March 31, 2021 the lake is still full, by November 16, the lake area had declined from 4.5 km2 to 1.9 km2, in Sentinel 2 images.
The drainage event appears to have been in the early spring as the lake is full on May 20, 2021 at the start of the winter season and at the end of the winter season on August 8, 2021 in Sentinel 2 images. The lake remained largely filled on Sept. 7, 2021, but had drained by Oct. 7, 2021.
By October 7, 2021 the lake had drained and two months later the lake is still not filling. As Steffen Glacier thins, its ability to impound this lake has diminished from 1987 to 1999, from 1999 to 2012 it diminished again. Now we may have another evolution in this process, with the more complete drainage starting in 2016 and now in 2021 the first event where refilling is not progressing.
Swanson River glaciers, British Columbia in Landsat images from 1984 and 2019. EM=East Meade Glacier, CG=Canning, red arrows=1984 terminus, yellow arrow=2019 terminus, purple dots=snowline. Points 1-8 are specific glacier locations with very limited to no retained snowcover.
The Swanson River feeds into Tagish Lake in NW British Columbia. The watershed is host to dozens of glaciers. Here we exaine the retreat of the two largest glaciers in the watershed from 1984-2019, referred to as “East Meade” and “Canning Glacier” in this post. We also look at the loss of snowcover on glaciers across the watershed in 2018 and 2019. These glaciers are in the northeast sector of the Juneau Icefield, sharing a divide with the retreating Meade Glacier, Alaska. The Juneau Icefield Research Program focuses on glaciers to the south of these including the retreating Llewellyn Glacier.
In 1984 the two glacier tongues terminated at 1000 m, red arrow and the snowline was at 1350 m, purple dots. This was a year of positive glacier mass balance on the Juneau Icefield, where I was working that summer. By 1998 there has ben modest retreat and the snowline is at 1400-1450 m. The retained snowpack at the end of the summer is limited to the upper reaches of the tributary glaciers. This year was a negative balance year on the Juneau Icefield where I was busy probing snowpack.
By 2018 Canning Glacier had retreated 1400 m since 1984 and terminated at 1100 m. East Meade Glacier had retreated 1100 m since 1984 and terminated at 1100 m. In 2018 there is no retained snowpack on East Meade Glacier. There is limited snowpack at the top of some of the tributaries in wind deposition zones, but many ofthe small alpine glaciers in the area have no accumulation zone. This summer led to the highest snowline ever observed on the Taku Glacier (Pelto, 2019). In 2019 the snowlineis even higher and the glaciers of the Swanson River basin are laid bare. There is no snowpack on East Meade (1) or on the adjacent tributaries at Point 2 and 3. There is no snowpack retained on Canning Glacier (4) or on the alpine glaciers east of the Juneau Icefield at Point 6 and 8. At Point 5 and 7 each has a small patch of retained snowpack at its upper margin close below a peak.
These back to back summers are the type of conditions that lead to the loss of alpine glaciers when they become frequent enough to remove any retained snowpack not just from that year, but from previous years. The retreat of East Meade and Canning Glacier is much less than Meade Glacier, 4 km 1986-2018, and similar to Warm Creek Glacier.
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Swanson River glaciers, British Columbia in Landsat images from 1998 and 2018. EM=East Meade Glacier, CG=Canning, red arrows=1984 terminus, yellow arrow=2019 terminus, purple dots=snowline.
Canadian Topographic map of the area EM=East Meade Glacier, CG=Canning Glacier and TL=Tagish Lake
Colonial Glacier in late summer false color Sentinel 2 images from 2019, 2020 and 2021. Yellow arrow indicates step that calves in 2020. Notice the ~10% of snowcover (bright white) remaining on glacier surface with more melt to come.
An alpine glacier disappears when it no longer has a persistent accumulation zone (Pelto, 2010). When this occurs the glacier is typically limited in size, but still can have significant ice thickness that takes time to melt away. Here we look at three glaciers I have worked on, where two disappeared and the third is disappearing in the North Cascade Range, Washington.
Lewis Glacier was a small cirque glacier in the drier part of the range, near Rainy Pass. In 1985 during my second visit to the Lewis Glacier, was the first time I confronted the idea of a glacier disappearing. We were able to peer down several crevasses and see the bottom of the Lewis Glacier, measurements indicated a maximum depth of 12 meters over an area the size of a football field/soccer pitch. This glacier had been selected for the North Cascade Glacier Climate Projects’s mass balance program assessing mass balance on 10 glaciers across the mountain range. This size made it attractive to observe in terms of response to climate change. The USGS map indicated a significant glacier with an area of 0.12 km2 in the 1950’s. By 1985 (top image) the glacier had lost half of its mapped area, there were still some significant blue ice areas, and areas of firn, snow several years old that is not yet glacier ice. Return visits each summer over the next few years chronicled the demise of the glacier. By 1988 (middle image) the glacier had shrunk dramatically even since 1985, the thickest ice measured was 5-6 meters. By 1990 the glacier was gone (bottom image), no blue ice left in the basin, the blue arrows indicate the lateral moraine above the now empty glacier basin. At the time I had not developed the model for forecasting glacier survival (Pelto, 2010). At bottom is 2021 image of the cirque basin with no glacier.
Milk Lake Glacier was a small glacier on the north flank of Glacier Peak in the North Cascades, Washington. The flat topography over the lake indicated a very thin unstable glacier area. In the USGS map for Glacier Peak in the based on 1979 aerial photographs, Milk Lake Glacier fills most of the Milk Lake Basin, had an area of 0.24 km2 with just a fringe of lake visible. Thw flat topography indicates the thin unstable nature of this part of the glacier. By 1988, Milk Lake had formed, a notably circular new alpine lake, the former glacier ice still filled part of the lake as ice bergs. The glacier had retreated to the margins of the lake fringing the west side of the lake. The fringing ice was clearly thin, we found several crevasses that reached bedrock 5-10 m down. In 1994 on a return visit in miserable weather (camera got too wet to function), there was no longer any icebergs in the lake and the lake was more of a jade to turquoise color. The fringing ice had lost about half of its area since 1988. This glacier remnant was not going to last long. By the end of 2005 the glacier had disappeared. The lake retains a beautiful jade color that will slowly become more azure as glacier flour settles. In 2021, see image bottom, the basin does not look like a recently glaciated basin.
Colonial Glacier is a cirque glacier in the Skagit River Watershed, North Cascades of Washington. The North Cascade Glacier Climate Project has made six visits to this glacier since 1985. Meltwater from this glacier enters Diablo Lake above Diablo Dam and then flows through Gorge Lake and Gorge Dam. These two Seattle City Light hydropower projects yield 360 MW of power. In 1979 the glacier was clearly thinning, having a concave shape in the lower cirque, but still filled its cirque, there is no evidence of a lake in this image from Austin Post (USGS). In 1985 my first visit to the glacier there was no lake at the terminus. We measured the glacier area at 0.92 km2. In 1991 the lake had begun to form, second image, but was less than 30 m across. The upper glacier was a smooth expanse of snow. By 1996 the lake was evident, and was 75 meters across. In 2001 the lake had expanded to a length of 125 meters. By 2006 the lake was 215 m in length, and had some thin icebergs broken off from the glacier front. From 2019-2021 a series of late summer Sentinel 2 images indicate the lack of retained snowcover necessary for survival. In 2019 15% of the glacier is snowcovered with three weeks left in the melt season. The terminus is just below a step in the glacier surface. In 2020 there is only 10% snowcover with two weeks left in the melt season. The portion of the glacier below the step has calved off and is now an iceberg in the lake. In 2021 the exceptional June heat wave took its toll and by the end of August the glacier only has 10% retained snowcover. The glacier area in 2021 is 0.26 km2, a 70% decline in area. The glacier has retreated 440 m and now is 520 m long. The lake has an area of 0.1 km2. The continued losses of Colonial Glacier are not being replenished by snowfall, this business model can only lead to the glacier disappearing. Colonial Glacier still has substantial area and thickness that will allow it to survive for a couple more decades. The continued loss of glacier area from Colonial and all other glaciers in the region reduce the mitigating affect of enhanced summer streamflow due to higher glacier runoff during warm dry periods.
Lewis Glacier cirque in Sentinel 2 image from 2021, Lewis Lake is lower right.
Milk Lake cirque in 2021, looking like a basin that was not recently glaciated.
Bernardo Glacier in Landsat images from 1986 and 2021 illustrating retreat at the southern (S), middle (M) and northern (N) terminus respectively. Red arrows are 1986 terminus locations, yellow arrows are 2021 terminus locations. Separation from Tempano occurs at S, while lake expansion occurs at M and N.
Bernardo Glacier is an outlet glacier on the west side of the Southern Patagonia Icefield (SPI) that currently ends in an expanding proglacial lake system, with three primary termini. Here we examine changes from 1986 to 2021 using Landsat images. Davies and Glasser (2012) indicate that over the last century the most rapid retreat was from 2000 to 2011. Willis et a (2012) note a thinning rate of 3.4 meters per year during this period of the Bernardo Glacier region, which drives the retreat. Mouginot and Rignot (2014) illustrate that velocity remains above 200 m/year from the terminus to the accumulation zone on Bernardo Glacier. Eñaut Izagirre visited the glacier in 2019 and provided images of the middle terminus of Bernardo Glacier, below.
Bernardo Glacier in Landsat images from 1998 and 2020 illustrating retreat at the southern (S), middle (M) and northern (N) terminus respectively. Red arrows are 1986 terminus locations, yellow arrows are 2021 terminus locations. Separation from Tempano occurs at S, while lake expansion occurs at M and N.
In 1986 Bernardo the southern terminus of the glacier was in tenuous contact with Tempano Glacier. The middle terminus primarily ended on an outwash plain with a fringing proglacial lake developing. The northern terminus had retreated a short distance south from a peninsula that had acted as a pinning point. By 1998 the northern terminus had retreated into the wider,deeper portion of the lake basin that was now filled with icebergs. The middle terminus remained grounded on an outwash plain, with proglacial lake expansion at the NW corner of the terminus. A small lake has developed completely separating Bernardo Glacier and Tempano Glacier. By 2003 the northern terminus had retreated 2 km from 1986, the middle terminus 1.5 km and the southern terminus 1.2 km in an expanding proglacial lake. By 2015 the lake between Tempano and Bernardo Glacier had drained, but a fringing proglacial lake at the margin of Bernardo Glacier was forming. In 2015 the northern terminus had retreated 3.5 km since 1986, the middle terminus 2.5 km and the southern terminus 2.75 km. From 2015 to 2020 the change of the southern terminus was limited to a limited expansion of the fringing proglacial lake, a limited retreat of the the northern terminus, while the middle terminus had retreated significantly into a wider portion of the lake basin. By 2021 the southern terminus had retreated 3 km since 1986, the middle terminus 4.6 km and the norther terminus 4.1 km. This led to a 8.7 km2 lake expansion at the middle terminus and a 7.8 km2 lake expansion at the northern terminus. Gourlet et al (2016) identify Bernardo Glacier as having thinner ice than other large outlet glaciers such Jorge Montt or O’Higgins, which helps lead to rapid terminus change. The retreat is similar to the extensive retreat observed at Dickson Glacier and Upsala Glacier.
Southern Andean huemel an endemic deer on the foreland beyond Bernardo Glacier (photograph from Eñaut Izagirre).
Middle terminus of Bernardo Glacier in 2019 taken by Eñaut Izagirre who considers this a condor-view.
Bernardo Glacier in Landsat images from 2003 and 2015 illustrating retreat at the southern (S), middle (M) and northern (N) terminus respectively. Lake expansion and then drainage occurs at S. Red arrows are 1986 terminus locations, yellow arrows are 2021 terminus locations.
Field Glacier on Aug. 31, 2021 in a Sentinel image. Note former glacier junctions A and B where the glacier has separated this century. The 7.5 km2 lake did not exist when I first visited this glacier.
The Field Glacier flows from the northwest side of the Juneau Icefield, and is named for Alaskan glaciologist and American Geographical Society leader William O. Field. Bill along with his work around Glacier Bay helped initiate the Juneau Icefield Research Program, which Maynard Miller then ably managed for more than 50 years. The JIRP program is still thriving today led by Seth Campbell. In 1981, as a part of JIRP, I had my first experience on Field Glacier completing a snowpit in its upper accumulation area. In the summer of 1983 I met with Bill to discuss where to setup a long term glacier mass balance program. I ended up selecting the North Cascade Range. In 1984 we skied back to the same snowpit site on Field Glacier, finding 3.8-4.1 m of retained snowpack in crevasses. At the end of our 11th field season in the North Cascade Range I spent a couple of nights at Austin Post’s (USGS) house and he reviewed his choice for a glacier to name after Bill, who had passed earlier that month. This was truly a remote area, which was why it had remained unnamed.
In 1984 the glacier began from the high ice region above 1800 meters, with two main branches joining at Point A and one significant tributary joining from the northern branch at Point B. There are icefalls near the snowline at 1350 meters on both the southern branch and the tributary entering at Point B. In 1984 the glacier descended the valley ending at 100 meters on the margin of an outwash plain. The meltwater feeds the Lace River which flows into Berners Bay. This post focusses on the changes from 1984-2021 using primarily Landsat imagery.
Field Glacier in Landsat images from 1984 and 2021 illustrating lake development, glacier separation at Point A and B and progressive detachment/separation at Point C,D and E. Purple dots indicate the snowline elevation at 1350-1400 m.
The USGS map from 1948 imagery and the 1984 imagery indicate little change in the terminus position. There is a narrow fringing proglacial lake along the southern edge of the terminus in 1984 with most of the margin resting on the outwash plain. In 1997 the proglacial lake was still a narrow fringing lake, though clearly poised to expand as it extended nearly the full perimeter of the terminus. By 2006 the proglacial lake at the terminus averaged 1.6 km in length, with the east side being longer. There were several small incipient lakes forming at the margin of the glacier above the main lake. In 2009 the lake had expanded to 2.0 km long and was beginning to incorporate the incipient lake on the west side of the main glacier tongue. There was also a lake on the north side of this tributary. This lake was noted as being poised to soon fill the valley of the south tributary and fully merge with the main lake at the terminus (Pelto, 2017). In 2013 Landsat imagery indicates the fragile nature of the terminus tongue that was about to further disintegrate, retreat from 1984-2013 was 2300 m and the lake had an area of 4.0 km2 (Pelto, 2017). This disintegration led to the separation of the two branches by 2017.
In 2021 the Field Glacier has two main branches are separated by 4 km, Point A. The tributary at Point B is also separated, no longer joining the main glacier. There is another separation imminent at the junction-Point E, 5 km of this former tributary. At Point C and D progressive detachment of smaller tributaries are evident. From 1984 to 2021, Field Glacier has experienced a retreat of 5500 m of the southern branch and 4100 m of the northern branch. The lake has expanded to 7.5 km2. Fringing lake on the northern branch indicates the lake will expand at least another 1 km. For the southern branch the glacier is close to what will be the lake margin. The record snowline elevation on the icefield in 2018 and 2019 (Pelto, 2019), has led to a continuation of the rapid mass balance loss, retreat, and lake development at Field Glacier. This glacier is experiencing retreat and lake expansion like several other glaciers on the Juneau Icefield, Gilkey Glacier,Llewellyn Glacier, and Tulsequah Glacier (Pelto, 2017).
Field Glacier in Landsat images from 1997 and 2017 illustrating lake development, glacier separation at Point A and B and progressive detachment/separation at Point C,D and E.
Field Glacier terminus in Landsat images from 1984 and 2013, dots indicate terminus, with pink arrows in 2013 indicating where marginal lakes have developed.
Field Glacier terminus in Landsat images from 2006 and 2009, red line is terminus with orange arrows indicating fringing lake development.
Loss of glacier connection between HPN1 and HPN2 in Landsat images from 2000 and 202o at Point A and B. Glacier tongue retreat at Point A from HPN1 and at Point C from HPN2. Formation of 1.4 km2 lake at HPN1.
HPN1, HPN2 and HPN3 drain adjacent sections of the the Northern Patagonia Icefield (NPI). HPN2 and HPN3 comprise the Acodado Glacier, with HPN1 being the next glacier to the north is. The lakes at the terminus of HPN2 and HPN3 were first observed in 1976 and had an area of 2.4 and 5.0 km2 in 2011, while HPN1 had no lake in 2000 (Loriaux and Casassa, 2013).Davies and Glasser (2012) noted that the Acodado Glacier termini, HPN2 and HPN3, had retreated at a steadily increasing rate from 1870 to 2011. Pelto, 2017 reported a retreat from 1987-2015 of 2100 m for HPN2 and 3200 m for HPN3. From 1987-2020 Acodado Glacier terminus HPN2 has retreated 2700 m and HPN3 has retreated 4100 m. The result of this retreat is an increase in lake area at HPN2 from 2.1 km2 in 1987 to 7.1 km2 in 2020 (Pelto, 2020). Glasser et al (2016) identified a 40% increase in lake area for the NPI from 1987-2015, and a 100 m rise in the snowline. Dussailant et al (2018) identified a mass loss rate of -2–2.4 m/year for HPN1, with thinning of over 4 m/year in the lower reaches in the vicinity of Point A and B. Here we examine the impact of the rising snowline, increased melt and resultant thinning on two glacier tongues that connected HPN1 to the accumulation zone region of HPN2 in 2000 and are now disconnected.
In the 2000 Landsat image glacier tongues extending from the accumulation zone region of HPN2 connect with HPN1 at Point A and Point B. At Point C an ice tongue extends 2.7 km upvalley from HPN2. By 2016 there is a disconnection at Point A with ice flowing south from HPN1 no longer joining the north flowing tongue. Point B is still connected. At Point C the ice tongue extends 1.8 km upvalley. By 2020 the connection at Point B has also been severed. At Point A ice no longer flows south into the valley from HPN1 and there is a 3.25 km long deglaciated valley between the two formerly connected ice tongues. At Point C the ice tongue from HPN2 has also been lost, a 2.7 km retreat. From 2000-2021 HPN1 has retreated 1.8 km leading to the formation of a 1.4 km2 lake. We can anticipate the rapid retreat of the glacier tongue from HPN1 at Point B during this decade. There is potential of short term formation of glacier dammed lakes at Point A and C now, and Point B in the future. There is not a hazard from drainage of these lakes that both reach tidewater via Rio Acodado within 15 km.
Loss of glacier connection between HPN1 and HPN2 in Landsat images from 2016 and 2021 at Point B. Glacier tongue retreat at Point A from HPN1 and at Point C from HPN2. Expansion of 1.4 km2 lake at HPN1.
HPN1 in Sentinel 2 image from Nov. 9, 2021 illustrating the 1.4 km2 lake at HPN1 that has formed this century and the deglaciated valley at Point A.
Drogpa Nagtsang Glacier, China retreat and proglacial expansion in 1993 and 2021 Landsat images. Red arrow is the 1993 terminus, yellow arrow the 2021 terminus and yellow dots are the snowline.
Drogpa Nagtsang Glacier, China is 30 km west of Mount Everest terminating in an expanding proglacial lake. The glacier begins on the Nepal border at 6400 m, and its meltwater enters the Tamakoshi River that supplies the Upper Tamakoshi Hydropower project a 456 MW run of river project that began operation in September 2021. King et al (2017) observed the mass balance of 32 glaciers in the Mount Everest area including Drogpa Nagtsang and found a mean mass balance was -0.7 m/year for lake terminating glaciers. In this basin from 2000–2016, mass balance loss resulted in surface elevation to decline at a rate of −0.63 m a−1, which drove a velocity decline of ~25% (Zhong et al 2021). They also noted that the area of proglacial lakes in glacier contact increased by ~204% . Pelto et al (2021) documented the exceptionally high winter snowline in the Mount Everest region from October 2020-January of 2021. Here we examine changes in Drogpa Nagtsang Glacier since 1993 and the snowline variation from October 2020-November 2021.
In 1993 Drogpa Nagtsang Glacier had a substantial number of coalescing supraglacial ponds on its relatively flat stagnant debris covered terminus. The snowline in 1993 was at ~5450 m. At Point A there is extensive crevassing indicating vigourous flow. At Point B a tributary glacier joins the main glacier. At Point C the glacier is a 1.2 km wide glacier tongue. Quincey et al (2009) observed flow of less than 10 m/a in lower 5 km of glacier in 1996 and peaking at 20-30 m/a 8 km from terminus. By 2015 a 2.7 km long lake has developed (Pelto, 2019). In 2021 the lake has expanded to 3 km long. At Point A there is no longer significant crevassing indicating reduced flow. At Point B the tributary no longer connects to main glacier. At Point C the glacier tongue has lost 30% of its width and debris cover width has expanded. The terminus area remains stagnant and the lake is poised to continue expansion.
Snowline variation from October 2020-November 2021, yellow dots. These are Landsat images except May 2021 is from Sentinel.
In October 2020 the snowline on Drogpa was at 5650-5700 m. By mid-January after the record winter heat wave of 2021 the snowline had risen to 5750-5800 m. In May of 2021 as the summer monsoon began the snowline was below the terminus of the glacier (5000 m). In June the snowline had risen to 5450 m. This is a summer acccumulation type of glacier, which means most of the accumulation snowfall occurs during the summer monsoon above the snowline simultaneous with high melt rates below the snowline. The snowline is close to mean freezing level, which has risen to 5400 m in recent years for the summer monsoon period (Perry et al 2020)The snowline than rises in the post-monsoon period. By October 2020 in the post-monsoon period the snowline had rise to 5600 m. A significant storm in late October lowered the snowline to 5250 m for November 2021. This suggests the snow free start to winter we saw last year will not occur this year.
Seven outlet glaciers of the Queulat glacier complex, Chile in 1987 and 2020 Landsat images. A=Rosselot Glacier and D=Colgante Hanging Glacier are the only ones in 1987 not terminating in a proglacial lake. The other five retreated from a proglacial lake since 1987 and Rosselot Glacier retreat has led to formation of two lakes.
Nevado Queulat, Chile is the centerpiece of the Queulat National Park in the Aysen Region. This massif is host to the Queulat glacier complex, which has a number of outlet glaciers. Rosselot Glacier is the largest glacier and it flows north draining into Lago Rosselot and then the Rio Palena. Colgante Hanging Glacier flows south and is the second largest terminating at the top of a cliff as a hanging terminus creating a spectacular waterfall. Paul and Molg (2014) observed a rapid retreat in general of 25% total area lost from glaciers in the Palena district of northern Patagonia from 1985-2011. Meier et al (2018) note a 48% reduction in glacier area in the Cerro Erasmo and Cerro Hudson region, since 1870 with half of that occurring since 1986. The 3.8 km retreat of Erasmo Glacierfrom 1998 to 2018 is a rate of ~200 m/year. Here we examined the changes from 1987 to 2021 of seven outlet glacier locations around the ice cap.
Seven outlet glaciers of the Queulat glacier complex in Queulat National Park in Chile in 2021 Sentinel 2 image. A=Rosselot Glacier and D=Colgante Hanging Glacier are the only ones in 1987 not terminating in a proglacial lake. The other five retreated from the proglacial lake since 1987 and Rosselot Glacier retreat has led to formation of two lakes.
In 1987 Rosselot (A) terminates against the valley where the valley turns to the east,and there is no lake at the terminus. In 1999 glacier retreat has exposed a new lake that is 900 m across. By 2015 the glacier has retreated south of a second lake that is 700 m across. In 2021 the glacier has retreated 250 m from the edge of the lake terminating at an elevation of 650 m. The total retreat from 1987-2021 has been 2100 m, ~60 m per year. This is the loss of 15% of the entire glacier length.
Seven outlet glaciers of the Queulat glacier complex, Chile in 1999 and 2015 Landsat images.
Outlet Glacier B terminates in a lake at 750 m. In 1999 the glacier has retreated to the top of a steep slope above the lake terminating at 850 m. In 2015 the glacier is terminating at 925 m and is receding up a north-south oriented valley. By 2021 the glacier has retreated 1100 m from the shore of the lake.
Outlet Glacier C terminates in a small fringing proglacial lake. By 1999 the glacier has retreated ~400 m to the base of a steeper slope, there is still ice cored moraine beyond the terminus. By 2015 a 500 m lake has formed beyond the terminus. In 2021 the glacier has retreated ~1000 m since 1987.
Colgante Hanging Glacier (D) terminates at the top of a steep cliff in 1987. The glacier reamins at the top of this cliff up to 2021, with considerable avalanching off the front into the valley below. A reconstituted glacier at the bottom of the cliff is thinning.
Outlet Glacier (E) terminated in a proglacial lake at 700 m elevation in 1987. By 1999 the glacier had a tenuous connection to the lake with a reconstituted stagnant area in contact with the lake. In 2015 the glacier no longer reaches the lake. In 2021 the terminus of the glacier is 400 m from the lake.
Outlet Glacier (F) terminated in a proglacial lake at 750 m elevation in 1987. In 1999 the glacier still connected to the lake. By 2015 the glacier had receded from this lake. In 2021 the glacier has retreated 350 m from the lake and terminates at 1000 m.
Outlet Glacier G is a stagnant debris covered glacier tongue that is in contact with a proglacial lake in 1987 and 1999. By 2015 the glacier has retreated from contact with the lake. In 2021 the glacier has retreated 600 m across an outwash plain from the lake.
Barcaza et al (2017) indicate that Colgante Hanging Glacier did not retreat from 2000-2015, while Rosselot Glacier lost 0.9 km2.
Easton Glacier on Mount Baker in late August 2021, with less than 20% of the glacier retaining snowpack.
The exceptional heat of the summer of 2021 across glaciated mountain ranges of the Pacific Northwest, reduced snowcover extent from Mount Shasta, CA north to Mount Adams and Mount Baker, WA and east to Glacier National Park, MT, Kokanee Glacier, BC and Bonnet Glacier, Alberta. Here we examine late summer images to illustrate the extent of exposed bare ice and firn across glaciers in the region. For a glacier to be in equilibrium requires at least 50% to be in the accumulation zone, snow covered at the end of the summer. At the end of the summer the snowcovered area varied from 0-20% on all of the glaciers reviewed here, the snowcovered area is the accumulation area ratio. Low accumulation area ratios such as this indicate mass loss of at least 2 m w.e. in 2021 on these glaciers. That is the equivalent of losing a 2 m thick slide of ice off the surface of the entire glacier.
When there is a persistent pattern of snowcover loss on the upper part of the glacier this indicates the lack of a consistent accumulation zone indicating the glacier cannot survive (Pelto, 2010). One indicator of this is new bedrock being exposed on the upper glacier as seen on both Easton and Bonnet Glacier here.
As the winter season begins hopefully a La Nina pattern will deliver much needed deep snowpacks.
Sentinel 2 False and True Color images from 8-25-2021. Yellow arrows indicate where glacier is separating and blue arrows the small remanent of 2021 snowpack remaining. This remanent will not last to the end of the melt season.
Jackson and Blackfoot Glacier in early September Sentinel 2 false color images. Point A indicates exposed ice showing annual layers. Point B indicates exposed firn that had been retained through previous summers. The gray color of the firn indicates how dirty it is and that its albedo would enhance melting.
Adams Glacier on Mount Adams in Sentinel 2 True Color image from 8-30-2021. Pink arrows indicate icefall top and bottom. S=summit area, A=Areas where limited pockets of 2021 snowpack has been retained through August.
The upper reaches of Kokanee Glacier to Cond Peak (2800 m) with no retained snow in 2021. Bare ice is exposed on the lower half of the image, and firn, or multi-year snow above. Picture taken during fieldwork by Ben Pelto.
Bonnet Glacier in Sentinel 2 images indicating the emergence of bedrock due to thinning in the former accumulation zone, Point A. Note the lack of retained snowcover in both years with at least a month left in the melt season.
Watercolor painting of Sholes Glacier. The small figure is at the current terminus of the glacier, and the photo that inspired this painting was taken from where the glacier used to end about 35 years prior. By Jill Pelto
Sholes Glacier is on the northeast flank of Mount Baker, WA. We have spent the last 32 years completing detailed measurments on this glacier that has revealed a story of glacier mass balance loss, thinning, retreat, declining area, and a cascade of other consequences impacting other “ologies” beyond the glacier. If you are intrigued by many ologies, the Podcast by Allie Ward will be inspiring as it was to this title.
Sholes Glacier and stream gage station. We have constructed a rating curve for this station, that the Nooksack Indian Tribe maintains (Grah and Beaulieu, 2013).
The climatology of the region has shifted, with one key change being more frequent and intense heat waves. Glaciers and heat waves just are not compatible. Using daily maximum temperatures for the 1981-2021 period for Mount Baker from ERA5 temperature reanalysis, completed by Tom Matthews at Loughborough University, indicates that there have been 83 days where the maximum temperature exceeded 12°C, an average of 2 days/year. In the last five years there have been 22 days exceeding 12°C, over 4 days/year. There have been 16 days during 1981-2021 period when the maximum temperature exceeded 14°C, 75% (12) of these have been in the last five years.
Probing snow depth on Sholes Glacier in 2014, this is completed annually at a fixed network of over 100 locations.
In terms of glaciology the result of the climate shift is that the glacier has lost 25-30% of its volume from 1990-2021. The terminus has retreated 155 m while the area has decreased by 25%. The changes have been most rapid in the last 8 years. The two years of largest mass loss were 2015 and 2021. We measure both melting (ablation) on the glacier and runoff from the glacier. This combination allows determination of the amount of glacier runoff. During 24 heat waves in the region from 2009-2021 mean daily ablation during the heat waves has ranged from 4.5-7.2 cm w.e./day (w.e.=water equivalent). The highest rate of 7.2 cm was during the June 26-July 1, 2021 period.
Sholes Glacier in 2015 exhibiting the darkening of the surface that occurs in high melt years, increasing melt rates. How much black carbon and algae is part of this darkening is the research of Alia Khan (WWU).
For a glacier to be in equilibrium or have a positive mass balance the majority of the glacier must be in the accumulation zone, snow covered at the end of the summer, that is an accumulation are ratio (AAR) greater than 50%. Pelto and Brown (2012)noted that for Mount Baker an AAR of 60% is required for a break even balance for the year. From 2013-2021 the average accumulation area ratio has been 35%. For Sholes Glacier if 50% of the glacier is exposed ice and firn in early August that increases mass loss. The ice and firn for the same weather conditions have a 30-40% higher melt rate than the snowpack. An early season heat wave strips the snow off earlier exposing the darker faster melting glacier surfaces for longer further increasing mass loss, note image above.
Sholes Glacier in 2021. The glacier has retreated 170 m from 1990-2021, the terminus in 1990 is approximately whre the goats are crossing the stream.
Hydrology downstream in Wells Creek and the North Fork Nooksack River is changing in part because of the changes in glacier runoff. Glacier runoff is a major source of streamflow during the summer low-flow season and mitigates both low flow and high water temperatures (Pelto, 2015). This is particularly true during summer heat waves, but this ability has been diminishing in the region (Moore et al 2020) For the last 37 summers we have been in the field monitoring North Cascade glaciers response to climate change including during heat waves (Pelto, 2018). In the last decade we have made synchronous observations of glacier ablation and stream discharge immediately below Sholes Glacier, Mount Baker (Pelto, 2015). This in conjunction with observed daily discharge and temperature data from the USGS stations on the ~6% glaciated North Fork Nooksack River (NFN) and the unglaciated South Fork Nooksack River (SFN), contrasts and quantifies the ameliorating role of glacier runoff on discharge and water temperature during 24 late summer heat wave events.
Measuring discharge below Sholes Glacier in 2016.
Sholes Glacier and ablation measurements on Sholes Glacier indicate daily ablation ranging from 5-6 cm/day, which for the NFN currently yields 9-11 cubic meters/second. This is 40-50% of the August mean discharge of 24 cubic meters/second, despite glaciers only covering 6% of the watershed. In the unglaciated SFN warm weather events generated a mean stream temperature change of +2°C, only 1 event in the NFN generated this rise and the mean was +0.7°C. Durng the June 2021 heatwave from June 21-29 maxium daily stream temperature in SFN warmed 3°C, vs 0.8°C for NFN. This illustrates that a greater proportion of snowmelt, which NFN recieves, has limited the temperature rise. Discharge rose at least 10% in 20 of the 24 events in the NFN with an average increase of 24%. In the SFN all 24 events led to a decreased discharge with an average decrease of 20%. The primary response to these summer heat waes is increased discharge in the heavily glaciated NFN, and increased stream temperature in the unglaciated SFN.
Discharge change during heat waves in South Fork (decreases) and North Fork Nooksack River (increases) above. Below temperature change during heat waves in South Fork (significant rise) and North Fork Nooksack River (small rise).
Glacier runoff is a product of glacier area and melt rate. Overall glacier runoff declines when area reductions exceed, ablation rate increases. This has already occurred in the NFN and now glacier runoff is declining (Pelto, 2015). The measured ablation rate is applied to glaciers across the NFN watershed, providing daily glacier runoff discharge to the North Fork Nooksack River. For the NFN glacier runoff production was equivalent to 34% of the total discharge during the 24 later summer heat wave events. As the glaciers continue to retreat the NFN will have a declining mitigation of heat waves for discharge and temperature and trend towards the the highly sensitive SFN where warm weather leads to declining streamflow and warming temperatures.
Nooksack Falls heavily glacier fed.
Aquatic ecology in glaciated watershed in turn is impacted. Glaciers are important in maintaining sufficient discharge and stream temperature that are critical for salmon in the North Fork Nooksack. Some cold-water trout and salmon species are already constrained by warm water temperatures and additional warming will result in net habitat loss (Isaak et al 2012). In the Fraser River and Thompson River, BC fish community thresholds were obsrved for mean weekly average temperatures of about 12°C and again above 19°C (Parkinson et al 2015). Below 12°C the community were characterized by bull trout and some cold water species, between 12°C and 19°C by salmonids and sculpins and above 19°C by minnows and some cold water salmonids (Parkinson et al 2015). These thresholds indicated small temperature changes can be expected to drive substantial changes in fish communities. During the 24 warm weather events noted in the North Fork only two events exceeded 12°C, while in the South Fork 15 of the events exceeded 19°C. This suggest that both rivers are near a threshold that could alter the fish community.
In the North Fork Nooksack the number of returning chinook is divided into natural and hatchery spawned salmon. The Chum and Coho salmon data for the Nooksack River during the 1999-2013 interval indicate there are two salmon population peaks for each species. The early peak is in 2002 and the second peak occurs in 2010 (Washington Dept. Fish & Wildlife, 2020). Overall numbers have not sustained an increase and remain endangered.
Ice Worm counts as the sunsets, 110 worms per square meter.
The climatology and glaciology has been difficult for ice wormology On the glacier itself ice worm population density surveys conducted annually indicate the density of ice worms has decreased since 2000 and that even 10 m beyond the edge of the glacier on snowpack they do not exist. This combined with the reduction in glacier area indicate population decline of ice worms.
In 2009 we observed the largest goat herd 62 goats (13 kids), some of them seen here below Sholes Glacier.
The climatology has been more favorable in terms of Goatology.We have conducted annual mountain goat surveys in the Ptarmigan Ridge-Sholes Glacier region each years since 1984. Populations stayed steady from 1984-2000, before rising dramatically through 2010. The difficult winters of 2011 and 2012 reduced the population, followed by a recovery up to 2021.
Three year running mean of mountain goat census conducted each summer while we are working on Ptarmigan Ridge, Sholes Glacier and Rainbow Glacier.
From a Glaciers Perspective 