Mahsa Icefield Retreat and Separation, Baranof Island, Alaska

The Mahsa Icefield is at the headwaters of Takatz Creek.  This is a small glacier, not an actual icefield.  Five kilometers to the west is another small unnamed glacier at the headwaters of Sawmill Creek.  Here we focus on changes in the two glacier using Landsat images from 1986 to 2014.

Google Earth image

In 1986 the Mahsa Icefield is a contiguous glacier that extended 5 km from east to west, red arrow indicates  the mid-section of the icefield.  A separate glacier in Sawmill Creek, yellow arrows, was 2.1 km long and has no lake at its terminus.  In 1997 the Mahsa Icefield has separated into an east and west half, at the red arrow, and has lost all of its snowcover.  The glacier in Sawmill Creek is still a single ice mass, but has lost all of its snowcover, which happened in 1998, 2003 and 2004. In 2014 the Mahsa Icefield’s east and west half are separated by 300 m, red arrow.  There is very little snowcover remaining despite there is a month left in the melt season.  At the headwaters of Sawmill Creek a lake has formed as the glacier has retreated, the lake is 600 m long in 2014.  The glacier has also separated into a small upper and lower section.  This glacier has lost half of its area since 1986.  The retreat of these glaciers on Baranof Island is similar to the retreat of nearby Carbon Lake Glacier,Lemon Creek Glacier, and Sinclair Glacier. Lemon Creek Glacier has lost more than 25 m of glacier thickness during the 1953-2014 period when its mass balance has been observed by the Juneau Icefield Research Program, and has retreated more than 1 km (Pelto et al, 2014).

Landsat image 1986

Landsat Image 1997

Landsat image 2014

 

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Weddel Glacier Thinning-Retreat, South Georgia Island

Weddel Glacier is on the southeast coast of South Georgia Island.  It terminates in Beaufoy Cove just north of Gold Harbor.The change in glacier terminus position has been documented by Alison Cook at British Antarctic Survey in a BAS retreat map.  In 1958 it reached within 400 m of the coast at the outlet of Beaufoy Cove. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980s. For Weddel Glacier the retreat was rapid from 1960 to 1974 and was slow from 1992-2003.  Here we examine Landsat imagery from 1989 to 2015 to visualize and update this change.

Google Earth Image

BAS map of glacier terminus position

In 1989 the glacier terminates near the tip of a peninsula, red arrow in each image. The calving front extends southeast, orange dots. At the yellow arrow the glacier fills a small side valley adjacent to the main glacier. At the purple arrow is a small extension of the main icefall flowing down the bedrock step.
In 2002 there is only minor retreat at the red and yellow arrow, but thinning has led to the small extension of the main icefall being almost cutoff by bedrock. By 2015 the glacier has retreated 200-300 meters from the 1989 position and the main terminus is narrower. At the yellow arrow the side valley no longer has ice. At the purple arrow this is just bedrock now, there is no glacier extension flowing down the bedrock step. A close up the icefall in a 2009 Google Earth image indicates both the extensive crevassing but also the lack of glacier ice at the purple arrow, where an extension of the icefall formerly flowed. A Google Earth closeup of the terminus indicates that only a small section is still in contact with Beaufoy Cove in 2009, with land exposed at the orange arrows. This glacier is almost not tidewater and has terminated in shallow water since 1989, which helps explain a slower rate of retreat. The glacier has thinned more rapidly than it has retreated in the last 25 years. The retreat rate is less than nearby Bertrab Glacier, Konig Glacier and Neumayer Glacier on the same coast of South Georgia.

Landsat Image 1989

Landsat image 2002

Landsat image 2015

Google Earth icefall image

Google Earth 2009 image

Lys Glacier Rapid Retreat, Italy

Lys Glacier drains south from Lyskamm in the Monta Rosa Group of Italy.  This glacier has a long history of observations that have indicated two short term advances in the 20th century 1912-21 and 1973-85 amidst a broader retreat.  The net change for the 1915-2004 interval was a 600 meter retreat (Smiraglia et al, 2006). They also noted a 10% area extent loss from 1975-2003, and since the glacier was advancing up to 1985 this change occurred more rapidly.  The Italian Glacier Commission report on terminus change of this glacier annually in the two latest reports Lys Glacier retreated 10 m in 2012 and 20 m in 2011. The total reported retreat from 2005-2012 was 186 m, more than 20 m per year. Here we examine Landsat images from 1990 to 2014.

Google Earth Image

In 1990 two branches of the glacier merged in the valley bottom and extended to the red arrow marking the terminus of the glacier at that time.  The yellow arrow indicates the 2014 terminus position, and the yellow A indicates a prominent bedrock knob that a branch of the glacier encircles, pink arrows.  By 2013 the glacier in the main valley have separated, there are a few small lakes forming amidst the decaying stagnant ice tongue between the yellow and red arrow.  The bedrock knob at Point A has greatly expanded. In 2014 none of the termini reach the floor of the main valley.  As the stagnant ice melts, the lake area is expanding indicating that a new alpine lake will likely form.  The retreat from 1990-2014 is 1300 meters.  A closeup in 2009 from Google Earth indicates the two tongues with bedrock below separating them from the main valley floor, red arrows. There is still some relict ice below on the valley floor detached from the active glacier, blue arrows, that has small lake developing amid the stagnant ice. There is substantial crevassing above both actual termini, but not immediately. The retreat should slow now that the glacier has retreated onto steeper slopes, having lost the low elevation low slope valley tongue.
The retreat of this glacier is similar to that of nearby Verra Grande Glacier.
1990 landsat image

2013 Landsat image

2014 Landsat Image

Google Earth Image

Wright Glacier Retreat, Southeast Alaska

Wright Glacier is the main glacier draining a small icefield just south of the Taku River and the larger Juneau Icefield. Wright Glacier is 60 km east of Juneau and has ended in a lake since 1948. A picture of the glacier in 1948 from the NSIDC collection indicates the terminus mainly filling the lake, but breaking up. The glacier drains the same icefield as the retreating West Speel and Speel Glacier. The dark blue arrows indicate the flow vectors of Wright Glacier, light blue arrows flow vectors for adjacent glaciers. Despite being 30 km long this glacier has been given very little attention, maybe because it does not reach tidewater.

NSIDC Glacier Photograph Collection Photographer unknown.

Google Earth view

In 1984 the glacier ended at a peninsula in the lake where the lake turns east. This was my view of this glacier during the summers of 1981-1984 from the Juneau Icefield with the Juneau Icefield Research Program. Our bad weather came from that direction so keeping an eye on that region during intervals between whiteout weather events, the norm, was prudent. Here we examine Landsat imagery from 1984-2013 to document the retreat of Wright Glacier and the elevation of the snowline on the glacier. The red arrow indicates the 2013 terminus, the red arrow the terminus at the time of the image and the red dots the snowline on the date of the imagery. In 1984 the lake had a length of 3.1 km extending northwest from the glacier terminus. The snowline in mid-August with a month left in the melt season was at 1150 m. By 1993 the glacier had retreated little on the north side of the lake and 200 m on the south side. The snowline in mid-September close to the end of the melt season was at 1150 m. In 1997 the fourth in a five year run of extensive mass balance losses and high equilibrium lines in the region, noted on the Juneau Icefield (Pelto et al, 2013), the snowline had risen to 1450 m. The terminus had retreated 200 m on the north side since 1984 and 600 m on the south side. In 2003 the snowline was at 1250 m with a month left in the melt season. The terminus retreat on the north side and south side since 1984 had now evened out with 900 m of retreat. In 2013 the snowline was at 1150 m in mid-August and 1350 m by the end of the melt season. The terminus had retreated 1300 m since 1984 and the lake is now 4.5 km long. The lower 2 km of the glacier has many stagnation features on it, suggesting continue retreat. It is unclear how far the basin that will be filled by the lake upon retreat extends, but it is not more than 2 km from the current terminus, as a small icefall reflecting a bedrock step occurs there. This glaciers retreat has accelerated since 1984. To be in equilibrium the glacier needs a minimum of 60% of its area to above the snowline at the end of the melt season. This is to offset the 10-12 m of melt that occurs at the terminus. This requires a snowline no higher than 1150 m. The snowline has been above this level in 1994-1998, 2003-2006 2009-2011 and in 2013, which suggest the glacier cannot maintain its current size and will continue to retreat. The glacier has a larger high elevation than the West Speel and Speel Glacier that originate from the same mountains. The glacier is following the pattern of retreat of all but one of the glaciers of the Juneau Icefield.

1984 Landsat image

1993 Landsat image

1997 Landsat image

2003 Landsat image

2013 Landsat image

Yejyumaro Glacier Retreat Lake Expansion, Tibet, China

An unnamed glacier draining the west side of Yejyumaro Peak a Nepal-China border peak, into Tibet is referred to here as Yejyumaro Glacier. The glacier is at the headwaters of the Arun River, which crosses into Nepal at Kimathanka. A 335 MW hydropower plant is being planned for the Upper Arun River fed by this and other glaciers. The glacier is adjacent to Nobuk Glacier across the border in Nepal.
Google Earth images from 2002 and 2013 indicate both the glacier retreat and resulting lake expansion. Red arrow is the 1989 terminus position and yellow arrow 2013 terminus position. Notice the southern and northern arms joining and turning west. Both arms of the glacier are fed by the steep border peaks with considerable avalanching.

20002 Google Earth image

2013 Google Earth image

Landsat imagery from 1989 to 2013 is used to illustrate the response of this glacier to changing climate. In 1989 the glacier extended down the unnamed lake to a peninsula, with the lake being 2.3 km long. By 2000 the glacier had retreated from the peninsula, 150-200 m retreat since 1989. By October 2013 the glacier had retreated 700 m from the 1989 position into a narrower section of the lake. The lake is now 3 km long and still growing. A December 2013 image indicates how dry this region is during the early part of the winter with only a light snowcover across the glaciated areas and higher terrain. The last image is a the Google Earth closeup indicating the transverse crevasses that are above the terminus, the crevasses narrow moving up glacier away from the terminus and disappear 400 m above the terminus. These represent the acceleration near the calving front and the indicate that calving has helped accelerate glacier flow and glacier loss. This glaciers retreat is similar to so many in the area from Nepal such as the Nobuk Glacier that is adjacent to it in Nepal, and the many Tibetan glacier retreating along the the axis of expanding lakes, Reqiang, Matsang Tsanpo and Menlung Glacier.

1989 Landsat image

2000 Landsat image

2013 landsat image

2013 Landsat image

Google Earth closeup

Haworth Glacier Retreat, Selkirk Mountains, British Columbia

Haworth Glacier in the northern Selkirk Mountains of British Columbia drains into Palmer Creek, which flows into Kinbasket Lake, and then the Columbia River. This glacier is often visited by climbers as the Canadian Alpine Club has a summer base camp near the terminus of the glacier. The glacier has a low slope and limited crevassing that makes it a good training ground for climbing. Menounos et al (2008) noted an advance of this glacier overrunning a stump that has since been exposed by retreat in the period from 3800 years before present, similar in timing to many glaciers in the region. The stump remained buried until recent exposure.

Here we examine a series of Landsat images from 1986-2013 to identify the retreat and forecast whether the glacier can survive even current climate conditions. In each image the blue dots mark the snowline, yellow arrow is the 1986 terminus and the red arrow the 2013 terminus. In 1986 the glacier ended near the far end of the basin where a lake has since developed, yellow arrow. Snowcovers 30% of the glacier in the late summer of 1986, 55-65% is necessary for glacier equilibrium. By 1994 the glacier had retreated exposing the new lake basin, the glacier was 25% snowcovered. By 1998 the glacier had retreated 550 m since 1986, the glacier was 15% snowcovered. In 2009 the glacier was 20% snowcovered. In 2013 the glacier terminates at the red arrow indicating a retreat of 1000 m since 1986, 37 m per year. The glacier is 10% snowcovered. The percent snowcover in each year is much less than the 55% minimum needed for a minimum balance, the images are also not precisely at the end of the melt season. If a glacier does not have a consistent and persistent snowcover at the end of the melt season it has no “income” and cannot survive (Pelto, 2010). This glacier has managed to retain a very small area of snowcover, but given the ongoing thinning and the lack of avalanche accumulation on this glacier, it is unlikely to be enough to save this glacier. Bolch et al (2010) noted a 10% area loss for British Columbia glaciers from 1985 to 2005, Haworth Glacier is above this average. Tennant and Menounos (2013) noted that the fastest rate of loss on Columbia Icefield glaciers from 1919-2009 was during the 2000-2009 period. The glacier is not retreating as fast as some of the glaciers that also calve into lakes such as Columbia Glacier, British Columbia. Nearby Apex Glacier has retreated at a similar rate. Jiskoot et al (2009) observed the terminus change of 176 glaciers in the Clemenceau Icefield and adjacent Chaba Icefield, and noted an average retreat of 21 meters per year from the 1980’s to 2001.

1986 Landsat image

1994 Landsat image

1998 Landsat image

2009 Landsat image

2013 Landsat image

Kerguelen Island Glacier Retreat Forms New Lake District

On the east side of the Cook Ice Cap on Kerguelen Island a series of outlet glaciers have retreated expanding and forming a new group of lakes, red arrow. This area is just south of Lac du Chamonix which has existed. Here we examine the changes from 2001-2014 along using Landsat imagery. This is a retreat examined by Berthier et al (2009), and exemplified by the retreat of Ampere Glacier and Aggasiz Glacier from the same ice cap.

In 2001 at the red arrow is the north tributary of a glacier ending in the northernmost lake at the pink arrow. In the second lake is an island, marked with point A, this glacier has a secondary terminus ending at the yellow arrow. The southernmost glacier examined at the green arrow has retreated from one lake and does not end in a lake. By 2011 the northern tributary is starting to separate losing its connection with the Cook Ice cap, red arrow and retreating from the pink arrow. The distance from the island for the middle glacier has increased. A lake is forming at the yellow arrow. For the third glacier a lake has formed at the green arrow. The 2013 Landsat image still has snowcover obscuring the glacier boundaries. In January 2014, it is evident that at the red arrow the northern tributary has lost all connection with the Cook Ice Cap. The main terminus has retreated 700 m, expanding the lake it terminates in. With the loss of the northern tributary the retreat will continue. The distance from the island at Point A to the terminus of the middle glacier has increased 900 m indicating the retreat since 2001. The glacier is nearly at the western end of the lake it terminates in. At the yellow arrow the new lake is now 900 m long indicating a retreat of slightly less than this. The green arrow marks the 2013 terminus in each image of the southern of the three glaciers. This glacier has retreated 800-900 m leading to the continued expansion of a new lake. In just a decade we see the formation of two new lakes and the expansion of two others at the terminus of the three eastern outlet glaciers of Cook Ice Cap.

Kangiata Sermia, Retreat Southwest Greenland

Kangiata Sermia is an outlet glacier in Southwest Greenland that empties into the Kangersunaq fjord east of Nuuk. Thomas et al (2009) noted that Kangiata Glacier thinned most notably near its terminus decrasing up glacier to negligible thinning 30 km inland. They further found that the glacier bed was above sea level 40 km inland. Sole et al (2010) observed variations in the velocity of this glacier and found that there was a substantial spring speedup as the melt season began and then an even more significant slowdown for most of the summer. They noted that the net effect of the summer speed variations on annual motion is small (∼1%), indicating the lack of a meltwater induced overall acceleration. The velocity figure below is from Figure 4 of Ahlstrom et al (2013), indicating the annual velocity minimum is in late summer. Box and Decker (2011) noted that glacier retreated 100 meters/year from 2000 to 2010.

Google Earth image

Thomas et al (2009) Figure showing the bedrock and surface profile of Kangiata Sermia

Ahlstrom et al (2013) Figure showing seasonal velocity change of Kangiata Sermia

Here we examine Landsat imagery of the glacier from 1987 to 2013 to identify changes. In 1987 the two main termini of the glacier were joined, down fjord of an island that separates the two branches. The terminus in each image is indicated by red dots, the yellow arrow note an island in the middle of a peripheral ice dammed proglacial lake, the pink arrow a minor terminus on the north side of the island and the orange arrow a medial-lateral moraine comples extending into the glacier. By 2001 the glacier terminus has separated into two parts, with a retreat of jsut over 1 km in the 14 years. The proglacial lake is still full, yellow arrow. The upglacier minor terminus is developing a lake at its terminus as it retreats. The orange arrow indicates the expansion of the moraine complex as the glacier thins. By 2006 the main terminus has continued to retreat up the south side of the island 1.5 to 2 km since 2001. The proglacial lake level has declined and the island has become a peninisula. The thinning ice is simply not able to impound as deep or large a lake. The minor terminus at the pink arrow has developed a lake that is over 1 km long. In 2013 the changes from 2006 are limited, the moraine complex has continued to expand. The overall retreat from 1987 to 2013 is 3 km. The retreat is similar to that of Narssap Sermia , Kuussuup Sermia, and Qaleraliq as each responds to the climate warming. The lake is a bit larger, though the lake does fluctuate through an annual cycle filling and draining. Google Earth imagery indicates the lake at an even lower level, it no longer fills to nearly the level of 2001. This lake is similar to Tiningnilik in its size and location, but has lost more of its volume. The lake at the pink arrow is 1.2 km long. Each winter the fjord in front of the glacier freezes and the terminus protected from calving can advance. The Google Earth closeup image indicates the heavily crevassed nature of both termini indicative of rapid flow. On April 2, 2014 the fjord is quite filled with sea ice to the southeast bend 50 km from the terminus. The terminus is not distinct in this particular image.
1987 Landsat image

2001 Landsat image

2006 Landsat image

2013 Landsat image

2012 Google Earth image

2012 Google Earth image

April 2 2014 MODIS Image

Khatling Glacier Retreat, Uttarakhand, India

Khatling Bamak (Glacier) is the headwaters of the Bhilangana River in Uttarakhand, India. The Bhilangana River flows into the Tehri Reservoir(2400 MW), that along with the Bhilangana River’s three small hydropower projects (50 MW), make these glaciers key contributors to regional hydropower. The glacier was formerly joined with the Ratangrian Glacier as indicated by the map, but the two have separated with the Ratangrian Glacier now terminating 1.7 km upvalley of this former connection. The 10 km long glacier is fed by several mountain peaks including Jaonli over 6000 m. The lower section of the glacier is debris covered.
Here we examine satellite imagery from 1998, 1999, 2011 and 2013 to identify recent changes. The yellow arrow in the images indicates the lower limit of the clean ice in 1998, the pink arrow the lower limit of the clean ice in 2013. The red arrow indicates a significant tributary to Khatling Glacier joining from the south. The terminus is not evident in the Landsat images, but can be observed in the Google Earth imagery.

In 1998 the southern tributary joins the Khatling Glacier at 4500 m, 2.5 km upglacier of the terminus. The clean ice extends to within 1 km of the terminus. In the 1999 image the same connection with the southern tributary and location of the clean ice is evident. By 2011 the southern tributary is no longer connected to the glacier, red arrow. The clean ice does not reach the yellow arrow. The spread of the debris cover is not from additional avalanche input or flow from upglacier. The spread occurs as a glaciers ablation melts the clean ice faster and the debris cover where thick slows ice melt. This leads to topographic highs covered by debris cover that than slide-tumble down onto the clean ice. Without much input from upglacier the debris within the ice is melted out and can continue to concentrate at the surface. This is common among retreating glaciers with debris cover to have the debris begins to spread across the glacier. By 2013 the clean ice extent has retreated 1000 m from 1998 to the pink arrow of 2103. The southern tributary has retreated 200 m from its former junction. The terminus of the glacier has retreated 400 m from 1998-2013. A close up of the terminus from 2011 Google Earth imagery indicates the outlet river (pink arrow) issuing from beneath the stagnant debris covered ice (DC) and the distance from the terminus to the clean ice (CI). The lateral moraines of the Khatling and Ratangrian Glacier are also shown. The hummocky thin nature of the lower 700 m of the glacier is evident, light blue arrows, indicating an area that will be lost from the glacier soon. Khatling Glacier retreat is similar to that of nearby Gangotri Glacier and Jaonli Glacier that also feed Tehri Dam.

1998 Landsat image

1999 Landsat image

2011 Landsat image

2013 Landsat image

2011 Google Earth image

Heaney Glacier and Cook Glacier Retreat, South Georgia Island

Heaney Glacier and Cook Glacier were merged near the terminus and reached the coast of St. Andrews Bay on the east coast of South Georgia Island in 1975. This is illustrated in a Geomorphology map of the area compiled by Chalmers Clapperton, and David Sugden produced with the support of the British Antarctic Survey, the glaciers terminates along the coastline.
Photograph of 1980 BAS map

2007 Google Earth Image

Here we use Landsat images to examine glacier change from 1989 to 2014. In 1989 Cook Glacier had retreated from the coast, and a small 200-300 m wide proglacial lake has formed at the end of the glacier, red arrow. The yellow arrow marks the 1989 terminus of Heaney Glacier in 1989 which is 800 m from the coast, pink arrow indicates 2014 terminus position. Point J marks the junction of the two glacier which is debris covered ice in 1989. The next image in 1999 indicates modest retreat of both glaciers. In 2003 Cook Glacier has retreated 500 m from the coastline, and Heaney Glacier is now 1100 m from the coast. In 2012 a small lake is developing at the front of the Heaney Glacier and the Cook Glacier proglacial lake has expanded to 700 m. In 2014 the narrow lake forming as Heaney Glacier retreat’s is now 600 m long and the glacier terminus is 1800 m from the coast, pink arrow. This is an 1000 m retreat from 1989 to 2014, 40 m/year. Point J is now fully deglaciated with Cook and Heaney Glacier being fully separated. Cook Glacier has retreated 900 m from the coast and 600-700 m since 1989. The proglacial lake, red arrow is 750 across and is still expanding as the glacier retreats. The story at this point is familiar with that of other land terminating glaciers on South Georgia Island, Konig Glacier and Purvis Glacier, with substantial accelerating retreat and lake formation at the terminus. Cook et al (2010) and Gordon et al (2008) have emphasized that this pattern is island wide with many calving glaciers having faster retreat.

1989 Landsat image

1999 Landsat image

2002 Landsat image

2012 Landsat image

2014 Landsat image

Juneau Icefield Glacier Terminus Change from Landsat 5 1984 to Landsat 8 2013

The Juneau Icefield Research Program (JIRP) has been examining the glaciers of the Juneau Icefield since 1946. Until the NASA Landsat program began field measurements and aerial observations were the only means to observe the glaciers of the icefield. For more than 40 years it was Maynard Miller, U of Idaho, who led this expedition that has trained so many of today’s glaciologists, today it is Jeff Kavanaugh, U of Alberta. Given the difficult weather conditions that produce the 4000+ square kilometers of glaciers, this was not a task that could be done comprehensively. Here we examine the changes from the August 17, 1984 Landsat 5 image to the June 21, 2013 image from newly launched Landsat 8. Landsat 5 was launched in 1984, Landsat 8 launched in 2013. The Landsat images have become a key resource in the examination of the mass balance of these glaciers (Pelto, 2011). The August 17th 1984 image is the oldest Landsat image that I consider of top quality. I was on the Llewellyn Glacier with JIRP on the east side of the icefield the day this image was taken. On June 21, 2013 JIRP’s annual program had not begun, but the field season is now underway once again observing fin and reporting from the field across this icefield.
Post reblogged at NASA

First we have the two reference images of the entire icefield that indicate the location of the 12 main glaciers we focus on here. Followed by a chart indicating the amount of terminus change, 14 glaciers have retreated and one has advanced.
This is followed by 12 closeup glacier by glacier comparisons of the terminus, with the 1984 image always on the left and 2013 on the right, the 1984 margin is marked with red dots and the 2013 with yellow dots. This is an update to an examination of the Juneau Icefield terminus changes from 1948 to 2005. There are also links to more detailed discussions for each glacier, as the focus here is on the 1984 to 2013 changes visible in the images here. The images were first overlain in ArcGIS and the terminus change based on three measurements one at the glacier terminus midpoint, one each halfway to the margin from the mid-point. The exception is the Taku Glacier which is based on the JIRP field measurement mean and the Llewellyn where three measurements are made on each of the two termini, the average is then rounded to the nearest 100 m. The ongoing retreats reflects the long term negative mass balance of the glaciers with the exception of the Taku Glacier. The ongoing warming of our globe will continue to lead to retreat. The glaciers are all fed from the central portion of the icefield that always has a large snow covered area even at the end of recent warm summers.

August 17, 1984 Landsat 5 image: N=Norris, L=Lemon Creek, M=Mendenall, H=Herbert, E=Eagle, G=Gilkey, A=Antler, F=Field, LL=Llewellyn, Tu=Tulsequah, TW=Twin and T=Taku.

June 21, 2013 Landsat 8 image

1984-2013 chart of terminus change of individual glaciers from 1984 to 2013, see individual images below for the observed changes.

From 1984 to 2011 Norris Glacier has retreated 1100 m. The glacier terminus that has been ending in a proglacial lake for the last 40 years is now mostly grounded. Since 1984 the northern half of this lake has formed and the long term lake development is discussed in a more detailed discussion on Norris Glacier.

In 1984 Lemon Creek Glacier (L) has pulled back 300 m from a small lake it reached in 1984. Lemon Creek Glacier has a long term mass balance record that indicates more than 15 m of thinning from 1984 to 2012. This thinning is more dramatic than the 300 m retreat that has occurred. The yellow arrow indicates a tributary that no longer connects to the glacier.

Mendenhall Glacier is the most visited and photographed terminus in the region. The glacier in 1984 ended at the tip of a prominent peninsula in Mendenhall Lake. By 2013 the terminus has retreated 1200 m, with an equal expansion of the lake. The red arrows indicate a tributary that decreased dramatically in width and contribution to the main glacier. This is the location of Suicide Basin, where a lake has formed the last two summers and then rapidly drained. A nice set of images of the glacier are provided by Matt Beedle.

Herbert Glacier has retreated 600 m since 1984. The width of the terminus has also declined. The red arrow indicates a tributary that no longer feeds the main glacier.

Eagle Glacier has retreated from the edge of a lake in 1984. The retreat of 1100 m is rivaled by the width reduction of the glacier in the lower 3 km. Eagle Glacier‘s ongoing retreat is examined in more detail.

Gilkey Glacier had begun to retreat into a proglacial lake by 1984, the lake was still just 1 km long. A short distance above the terminus the Gilkey was joined by the sizable tributaries of the Thiel and Battle Glacier. By 2013 the glacier has retreated 3200 m, the lake is now 4 km long. Thiel and Battle Glacier have separated from the Gilkey Glacier and from each other. Thiel Glacier retreated 2600 m from its junction with Gilkey Glacier from 1984-2013 and Battle Glacier 1400 m from its junction with Thiel Glacier

Antler Glacier is actually a distributary glacier of the Bucher Glacier, which in turns joins the Gilkey Glacier. As this glacier has thinned, less ice has overtopped the lip of the valley that Antler occupies. In 1984 Antler Glacier was 3 km long descending the valley to end near a proglacial lake, that it had recently occupied. By 2013 the glacier was just 400 m long, having lost 2600 m of its length.

Field Glacier in 1984 ended at the edge of an outwash plain with a few glimpses of a lake developing near its margin. By 2013 a substantial lake has formed at the terminus and the glacier has retreated 2300 m. A lake has also developed at the first terminus joining from the east, most of the width of this glacier has been lost. It is clear that the two lakes will merge as the retreat continues.

The second largest glacier of the icefield is the Llewellyn Glacier which is in British Columbia. The glacier has several termini, here we examine two of them that have retreated 900 m from 1984-2013. Hoboe Glacier is another terminus that has been examined, but not in this post. This has led to formation of new lakes, and water level changes in existing lakes. Matt Beedle has examined the recent changes at the terminus.

Tulsequah Glacier in 1984 ended at an outwash plain with a small marginal lake beginning to develop, red arrow. By 2013 a large proglacial lake has developed due to the 2500 m retreat. A side valley down which a distributary tongue of the glacier flowed in 1984 has retreated out of the valley by 2013, pink arrow.

The East and West Twin Glacier are receding up separate fjords, though they are fed from a joint accumulation zone. The East Twin is a narrower glacier and has retreated 900 m. The West Twin has retreated 600 m, at an elbow in the fjord. Elbows like this are often good pinning points that are a more stable setting, once the glacier retreats out of the Elbow retreat should speed up.

Taku Glacier is the largest glacier of the icefield and unlike all the others it has been advancing non-stop over the last century. The sustained positive mass balance from 1946-2012 has driven this advance (Pelto, 2011), this led to the glacier thickenning along its entire length. Since 1950 observations of velocity near the snowline of the glacier by JIRP indicates that the glacier has had a remarkably steady flow over the past 50 years (Pelto et al, 2008). Since 1988 the glacier has not been thickening near the snowline as mass balance has declined. We have been able to observe the snowline movement in satellite images to help determine the mass balance. The changes at the glacier front are quite variable as the glacier advances. JIRP measurements of the terminus indicate this from 2001-2008 with an interactive map from Scott McGee, indicating advances in some area, minor retreat in others and back and forth in others. In 2012 JIRP was back at the terminus creating the map below. There is no change at the east and west side of the margin since 2008 and 55 to 115 m of advance closer to the center.

Hoboe Glacier retreat, British Columbia

The Hoboe glacier is a distributary tongue of the Llewellyn Glacier draining the Juneau Icefied in Northwest Britsh Columbia. In 1984 I had the opportunity to hike the length of the glacier carrying supplies to the terminus for a master thesis research project of Richard Campbell at the Univ. of Idaho, during the JIRP summer field season. The glacier is 4 km long separating from the Llewellyn Glacier at 3800 feet and ending at approximately 3000 feet. This is our view from the glacier surface notice the evident trimline above the ice surface showing how thick the glacier used to be.This glacier has receded 2200 meters since early visitors to the area mapped its terminus around 1910, and 3900 m from its maximum advance of the Little Ice Age. The Google Earth views below are from 2001 images. The glacier has retreated 450-500 m in the fifty years that the Juneau Icefield Research Program has been examining it. The first view is looking up glacier and the next two looking down glacier. In all three a trimline is evident where vegetation has not had time to develop due to retreat of the last 75 years. The image above is an aerial photograph taken by Don McCully of JIRP. The trimline in the photograph is 75-85 meters above the glacier surface indicating the thinning that has occurred in the last century. Nearly one meter a year due to the recent climate change that has enhanced summer melting and reduced winter snowfall. The Hoboe Glacier is continuing its retreat like all but one of the nineteen outlet glaciers of the Juneau Icefield. Including the Gilkey Glacier and Tulsequah Glacier.