Visualizing Glacier Melt Impacts

On September 4, 2015May 2, 2024 By mspeltoIn glacier climate change, Glacier Observations, glaciers salmon, North Cascade Glaciers1 Comment

Key questions emerge from the summer of 2015 in the Pacific Northwest glacier basins. That can both be visualized and quantified.

With record temperatures and minimum flows in most rivers in the Cascade Range during July and August of 2015, a key question was how much did glaciers contribute in basins that are glaciated? Note the water pouring off the glacier and the lack of snowcover in the first few minutes of the video.

You can examine flow per unit watershed area as a first order observation. In the unglaciated South Fork discharge was 0.5 cfs/square mile, rising to 0.7 cfs/square mile in the lightly glaciated Skykomish River and 4.3 cfs/square mile in the heavily glaciated North Fork Nooksack. For a more direct measure we measured ablation from July 29 to August 17th in the North Fork Nooksack and Skykomish River basin. With the Nooksack Tribe we also measured discharge below glaciers in the North Fork but those recorders are still deployed in the field.

Because the glaciers had mostly ice, not snow at the surface, melting was enhanced. We found in the Skykomish Basin that glacier runoff was 45 CFS versus a mean discharge of 375 CFS , this is 12% of the total flow despite covering only 1.3 % of the basin. In the North Fork Nooksack glacier runoff was 340 CFS versus total flow of 460 CFS, this is 74% of the total flow though only 6.1 % of the basin has glacier cover. In both cases the glaciers contributed a river flow percentage 12 times greater than the percent of basin area they cover. With a substantial loss in glacier area occurring this summer, next year glacier runoff for the given climate conditions will be reduced. Given this higher flow the glacier fed streams offer less stressful conditions this summer to salmon.

How much did glacier runoff water temperature amelioration?

In the South Fork Nooksack without glaciers stream temperature was above 20 C on eight days between Aug.1 and Aug. 20. In the North Fork Nooksack with glacier contribution, the stream temperature peaked at 13-14 C.

With the early loss of snowcover and exposure of the underlying ice, how are glacier ice worms impacted? In the video note ice worms featured in the first minute in a glacier filled crevasse.

These worms live on snow algae primarily, which would seem to be in short supply in a summer with limited snowpack on the glaciers. How well can they survive being on the glacier ice for extended periods? For the 21st year we conducted ice worm population surveys. The numbers were the lowest we have seen at 175-250 ice worms per square meter, but it should be next year when the full impact would be evident.

How much glacier area will be lost? Note the visual of terminus retreat.
The summer is not over, but our observations indicate a 5-7 % volume loss will occur. This should be approximately equaled by area loss. Hopefully good satellite imagery in September will provide a specific answer. The Aug. 17th Landsat image is excellent. Retreat just this summer has been 40 m on Easton Glacier, 32 meters on Columbia Glacier, 25 meters on Sholes Glacier and 30 meters on Lower Curtis Glacier.

Aug. 17 Landsat image. Arrows indicate areas where we observed rapid area loss of glacier ice this summer.

Glaciers have the Wrong Business Model

On December 18, 2014January 1, 2015 By mspeltoIn Glacier Observations

This is the story of a glacier that recently went to a bank for a loan, the Sholes Glacier, North Cascade Range, Washington. … “A recent resolution of mine is to work to change my future. I first had to go to the trouble of getting registered as a business so the bank would even recognize my existence, simply having existing on a map was not sufficient. This despite the fact that the water I store and release each summer is valuable to many businesses. I was ushered into the loan office where my basic need was explained, I need to replenish my main asset snow and ice, otherwise the water resource service I provide to others will diminish. The documentation requested included the state of my overall sector. The World Glacier Monitoring Service, collects data on glacier mass balance and terminus change from around the globe, showed that my sector had lost net assets for 25 consecutive years, see below. This graph showed not only that global glacier mass balance has declined 25 years in a row, but that North Cascade glaciers have lost an equivalent amount of volume, the 2014 data is preliminary.

Global Glacier Mass Balance

In fact auditors, glaciologists, have examined my asset sheet each of the last 25 years, and this data was not helpful. I then provided my own net asset sheet indicating a 25% asset loss in the last 20 years. The increased stream of liability from me was eating the long term assets, that were literally no longer frozen. The bank officer, took a hard look and pointed out that, “banks loaned money with the expectation that there would be a return on their investment, improved assets of the loan recipient being crucial”. Given the recent history in the glacier sector I was told, “that our business model was wrong. We cannot expect after 25 consecutive years of loss that a positive asset trend is possible”. I noted that the business model was hard to change and that is was the overall “business” climate that was wrong. This yielded a final rejection, “that maybe true, but until the business climate changes, you still have an unsustainable business model, and any loan would likely simply melt away, so to speak”. So I ask for advice. What can I use for a business model? Will the business climate change in time for my business… How about the other businesses I supply too? I am afraid Kickstarter is not an option. Examine the other glaciers and their stories to see that my story is not unique.

Sholes Glacier, North Cascades of Washington assets melting away.

Snow melt from August 4th to Sept. 12th, 2013 on Sholes Glacier.

Annual balance of glaciers in western North America all losing assets.

Ampere Glacier Retreat Kerguelen Island

On June 5, 2011April 27, 2014 By mspeltoIn Glacier Observations1 Comment

Kerguelen Island sits alone at the edge of the furious fifties in the southern Indian Ocean. he island features numerous glaciers, the largest being the Cook Ice Cap at 400 square kilometers. A comparison of aerial images from 1963 and 2001 by Berthier et al (2009) indicated the ice cap had lost 21 % of its area in the 38 year period. T In this paper they focused particular attention on the Ampere Glacier draining the southeast side of the ice cap. Berthier et al (2009) noted a retreat from 1963 and 2006 of 2800 meters of the main glacier termini in Ampere Lake. The lake did not exist in 1963. The map below is from the paper indicating the terminus position. A second focus of their work was on the Lapparent Nunatak due north of the main terminus and close to the east terminus. A nunatak is a ridge or mountain surrounded by a glacier, really an island in a sea of ice. The nunatak expanded from 1963-2001, in the middle image below from Berthier et al (2009), but it was still surrounded by ice. The bottom image is from Google Earth in 2003. Given our current climate I wondered what might have changed in the last few years. Landsat images from 2001, 2009, 2011 and 2013 indicate the retreat of the main terminus at the orange arrow and the secondary terminus at the red arrow. The east terminus has retreated 1500 meters since 2003 leading to the expansion of a new substantial lake. The main terminus has retreated additionally 800 meters from 2001-2013. Here the terminus has pulled back from the tip of the peninsula on the west side of the terminus, which the orange arrow crosses in each image. This glacier is experiencing the same climatic warming that has led to the retreat of other glaciers in this circum-Antarctic latitude belt, Arago Glacier further south on Kerguelen, nearby Aggasiz Glacier Stephenson Glacier on Heard Island and Neumayer Glacier on South Georgia. In this ever changing world, it is melting that is changing our maps.
2001 Landsat image

2009 Landsat image

2011 Landsat image

2013 Landsat image.

Thiel Glacier Alaska ongoing retreat

On January 2, 2011January 2, 2011 By mspeltoIn Glacier Observations

Thiel Glacier is a valley glacier in the Juneau icefield of Alaska. The glacier was a tributary of the Gilkey Glacier and is shown as such in USGS maps. From 1948-2005 the glacier has retreated 2100 meters from its former junction with the Gilkey Glacier. Below is the USGS map of the area showing the junction of the Battle, Gilkey and Thiel Glacier. The same view from the 2005 Google Earth imagery indicates the separation of the three glaciers and the emergence of a new deglaciated valley section. In 1984 looking down at the glacier from its highest elevation, it was clear that the glacier had too small of an accumulation area to support the long, low elevation valley tongue of the glacier. From that vantage I could not see the terminus. The snowline at the end of the summer typically is at 4000-4500 feet at the end of the melt season, leaving only 45% of the glacier in the accumulation zone. For a glacier to be in equilibrium at least 60% of the glacier needs to be in the accumulation zone. The upper margin of the glacier is outlined in blue and the snowline indicated with blue arrows in the image below. The current glacier terminus is stagnant and the retreat is ongoing. At the terminus a close examination of the 2005 imagery forth indicates a series of concentric crevasses at the terminus. Such crevasses typically are the indicative of a collapse feature. Usually it is a subglacial lake that drains that had supported the terminus to some extent. Above this point the ice is stagnant lacking tranverse crevasses that would indicate movement. The surface of the glacier has a rough cross profile as a result without active movement to even out the profile. Areas of debris generally are prominent as the debris is insulating the ice underneath. The 2005 terminus is at 650 feet, compared to the same location in the USGS maps of 1500 feet. This nearly 900 feet of thinning is depicted by the surface wall overlay added to Google Earth, the top of this wall is at 1500 feet. In the foreground is the Gilkey Glacier which the Thiel formerly joined and the new deglaciated valley. This glacier will continue to retreat rapidly with the current climate much like the nearby Hoboe Glacier and Tulsequah Glacier and Lemon Glacier

Methods for assessing and forecasting the survival of North Cascade, Washington glaciers

On December 29, 2010December 29, 2010 By mspeltoIn Glacier Observations

This paper was just published, Methods for assessing and forecasting the survival of North Cascade, Washington glaciers. It represents the third in a series of papers that looks at methods to identify when an alpine glacier will not survive. The first paper was using the change in thickness along a profile up the center of the glacier. Glaciers that were thinning appreciably and similarly along their entire length were determined to be in disequilibrium and would not survive. The second paper looked at glaciers that experienced thinning in the accumulation zone as distinguished by emergence of bedrock outcrops, marginal recession in the accumulation zone and overall accumulation zone thinning. Glaciers that were thinning in the accumulation zone were forecast to not survive. In this paper the model is expanded to look at the percentage of a glacier that is snowcovered at the end of the melt season. This is the accumulation area ratio. Typically a glacier needs to be 60% snowcovered or more at the end of the melt season to have an equilibrium balance. If the glacier has an AAR of less than 30% frequently, those glacier have been noted as thinning appreciably in the accumulation zone and will not survive. To survive a glacier must of course have a persistent accumulation area, as snow is the income of the glacier. A glacier that lacks such a zone, then has only a melt zone-ablation zone, and only liabilities and will go out of business. Lets look at three glaciers that exemplify this issue. The first and third are forecast not to survive current climate, the middle glacier will. The first is Lynch Glacier the pictures are from 1960 and 2007, in the upper left of the glacier-the accumulation zone, you can note the emergence of bedrock outcrops, Point B. This indicates that snowcover is not persisting and this has become a melt zone even though it is near the head of the glacier. The second is Easton Glacier. This glacier descends the south side of Mount Baker. Even in the years with the poorest snowcover, such as 2009 the glacier remains snowcovered to the end of the summer over the upper third of the glacier. This image is from mid-Sept. 2009, mid-Sept. 2010 was a much better year. The last glacier is Foss Glacier which shows considerable shrinkage in the upper reaches of the glacier, what should be the accumulation zone, here the glacier is seen in 1985 and 2005. . Also notice the lack of an accumulation zone in 2005. This was the case that summer on Columbia Glacier (above) and Ice Worm Glacier (below) as well. 2003, 2004 and 2009 were other years in which accumulation was not retained on many North Cascade WA glaciers. The picture of Ice Worm Glacier contrasts the glacier from 2005 to 2009. The picture indicates more retreat at the top of the glacier at Point A.

Castle Creek Glacier, BC annual retreat recorded

On December 26, 2010December 26, 2010 By mspeltoIn Glacier Observations

Castle Creek Glacier is in the Cariboo Mts. of British Columbia. The glacier descends north-northeast for 6.3 km from 2825 meters to the terminus at 1,810 meters. During the last 50 years of retreat has left a series of annual terminal recessional moraines that indicate how much the glacier has retreated each year. The glacier has a remarkably uniform and relatively low slope for an alpine glacier. This is one feature that helps ensure that the retreat rate changes little from year to year as the glacier flow dynamics are consistent. There is no prominent icefall, there is no low slope terminus tongue that can stagnate. The extent of the glacier during the Little Ice Age is quite evident as the gray vegetation free zone. Castle Creek Glacier has receded every years since 1959 at total of 720 meters up to 2008, about 14 meters per year. The Universtiy of Northern Brictish Columbia as part of the Western Canadian Cryosphere Network has undertaken a detailed investigation of this glacier. Matt Beedle at UNBC has been the field leader for the project, and has had the chance to map and identify the annual recessional moraines. The three pictures below are from Matt Beedle. The first is a series of aerial photographs that have been cropped to show the same area. Note that in 1946 the glacier filled the view, by 2005 it barely makes the image. The period from 1971 to 1991 has the most notable recessional moraine ridges. Beyond the 1967 margin there are at least 10 moraine ridges
The recessional terminal moraines are not unusual features to be formed by a retreating glacier, however they are unusual to be formed each year and to be so well preserved. The recessional moraines are deposited on a till plain exposed by the glacier retreat. Often such moraines are ice cored and tend to disappear as the ice core melt outs, not the case here. The moraines form during the winter when the glacier continues to move and the terminus is not melting. In summer after the terminus area is exposed the terminus melts back. The Key as pointed out by Matt Beedle is summer temperature. Such moraines will not form on a glacier with a stagnant glacier tongue. Such moraines also do not form on glaciers that have a terminus area that is an avalanche runout zone that can bury the terminus some years.
The glacier fits the pattern of glaciers throughout the southern interior ranges of BritishColumbia and Alberta which Blch et al (2010) noted lost 11% and 25% of their area over the period 1985–2005 respectively.

Midtdalsbreen Glacier, Norway retreat Continues in 2010

On December 8, 2010 By mspeltoIn Glacier Observations

The Norwegian Water Resources and Energy Directorate is the most extensive national glacier monitoring program in the world. They noted in 2010 that 27 of 31 glaciers monitored retreated. Midtdalsbreen near Finse drains the eastern portion of the Hardangerjøkulen (Hardanger ice Cap). This glacier retreated 34 meters from 2009 to 2010 and has retreated 143 meters in the last 10 years. This retreat is less than the retreat of Rembesdalsskaka Glacier which drains west from the Hardangerjokulen and has retreated 311 meters in the last decade. The 2010 Image below indicates the area beyond the terminus that is quite fresh and lacks any new vegetation as yet, the small hillocks and ridges are ice cored. The debris has not stabilized yet. The terminus is quite lacking in crevasses and the slope modest, suggesting the retreat will be ongoing. Beyond the current margin are a series of low moraines some of them forming annually with no retreat from October-May and then summer retreat. Moraines like this tend to be ice cored when formed and are prominent. The moraine is really a 20-50 cm or debris overlying a core of dirty ice. Once this ice melts years later the once obvious moraines are hardly noticeable. The terminus of the glacier is well defined. The upper section of the glacier that drains the ice cap lacks clear margins. The ice cap generally does retain snowpack throughout the summer season, continuing to feed the glacier outlets. The reduction in the area and depth of this seasonal snowpack by summers end leads to less outflow from the ice cap through the outlet glaciers and hence terminus retreat.

Quien Sabe Glacier Retreat

On October 7, 2010October 10, 2010 By mspeltoIn Glacier Observations

The Quien Sabe Glacier in the North Cascades of Washington has experienced rapid retreat in the last 20 years. This glacier is the largest in Boston Basin near Cascade Pass, its name translates to “who knows?”, well we all know it is not enjoying recent climate. In the 1960 Austin Post photograph he gave to me in 1994, the glacier was heavily crevassed and advancing. By 1975 the advance had ceased, but little retreat occurred until 1987. This glacier faces south and is fed by avalanching off of Forbidden and Sahale Peak. The glacier retreated 1200 meters from its Little Ice Age maximum (moraine indicated with blue arrows) until 1950. Richard Hubley noted the advance by 1955, the total advance was 55 meters by 1975 (advance moraines noted with orange arrows). We were able to identify the advance moraine in 1985 when it was still quite evident. The smooth bedrock, Granodiorite in the basin, provides little friction for this glacier as it moves over the polished slabs. Today the terminus moraines from 1975 range from 150-250 meters from the current glacier terminus averaging just over 200 meters. For a glacier that averages 700 meters in length this is a significant loss of total area. There are a number of bedrock outcrops that have appeared above the terminus indicating how thin the terminal area is and that retreat is ongoing. . In 2009 the glacier lost almost all of its snowcover an occurrence that has become frequent in the last 18 years. In this August image the glacier is 25% snowcovered. Fortunately 2010 was a better year in terms of snowcover, with more than 50% of the glacier snowcovered at the end of the summer, photograph from Neil Hinckley.
Quien Sabe Glacier viewed from a similar location on the western side of the glacier in 1985 and 2007. The reduction in crevassing, thickness is evident as is the marginal retreat and emerging bedrock.

Lemon Creek Glacier Retreat Juneau Icefield Alaska

On July 26, 2010December 8, 2013 By mspeltoIn Glacier Observations2 Comments

Above is a paired Landsat image with 1984 left and 2013 right, indicating a 300 m retreat in this interval.

Annual balance measurements on the Lemon Creek Glacier, Alaska conducted by the Juneau Icefield Research Program from 1953 to 2013 provide a continuous 61 year record. This is one of the nine American glaciers selected in a global monitoring network during the IGY, 1957-58 and one of only two were measurements have continued. These show cumulative ice losses of –13.9 m (12.7 m we) from 1957-1989, of –19.0 m (-17.1 m we) from 1957-1995 and –24.4 m (–22.0 m we) from 1957-1998. The mean annual balance of the 61 year record is -0.43 m/a and a loss of at least 30 m of ice thickness for the full 61 year period from 1953-2013. In the second graph the similarity with other North American glaciers is evident (Pelto et al, 2013).

This negative mass balance has fueled a terminal retreat of 800 m during the 1953-1998 period, and an additional 200 meters of retreat by 2013. Below is a picture of the terminus enroute to Camp 17 in 1982, and below that from 2005. The annual balance trend indicates that despite a higher mean elevation and a higher elevation terminus, from thinning and retreat, mean annual balance has been strongly negative since 1977 (-0.60 meters per year). Dramatically negative mass balances have occurred since the 1990’s, with 1996, 1997 and 2003 being the only years with no retained accumulation since field observations began in 1948.

These data have been acquired primarily by employing consistent field methods, conducted on similar annual dates and calculated using a consistent methodology. The research is conducted from Camp 17 on a ridge above the glacier. This is a wet and windy place with three out of four summer days featuring mostly wet, windy and cool conditions in the summer. The camp was initially built for the IGY in 1957, and Maynard Miller and Robert Asher saw to its continued improvements through the 1980’s. The mass balance record have been were until 1998 precise, but of uncertain accuracy. Then two independent verifications indicated the accuracy (Miller and Pelto, 1999). Comparison of geodetic surface maps of the glacier from 1957 and 1989 allowed determination of glacier surface elevation changes. Airborne surface profiling in 1995, and comparative GPS leveling transects in 1996-1998 further update surface elevation changes resulting from cumulative mass balance changes. Glacier mean thickness changes from 1957-1989, 1957-1995 and 1957-1998 were -13.2 m, -16.4 m, and –21.7 m respectively. It is of interest that the geodetic interpretations agree fairly well with the trend of sequential balances from ground level stratigraphic measurements. The snowline of the glacier lies a short distance above a tributary glacier from the north that has separated from the main glacier since 1982. The snowline on the glacier was just below this juncture in the 1950’s and 1960’s but now has typically been above this former juncture. The two images below are looking down and upglacier from this former tributary in 2005.

At the head of the glacier is a supraglacial Lake Linda, which now drains under the ice. Robert Asher in the late 1970’s and 1980’s mapped this lake system when it drained under the head of the glacier not down under the terminus of the glacier.

On July 8, 2010February 5, 2013 By mspeltoIn Glacier Observations, Uncategorized4 Comments

The Lower Curtis Glacier on Mount Shuksan advanced from 1950-1975 and has retreated 150 meters from 1987-2009. A longitudinal profile up the middle of the glacier indicates that it thinned 30 meters from 1908-1984 and 10 m from 1984-2008. Compare the 1908 image taken by Asahel Curtis (glacier named for him) in 1908 and our annual glacier shot in 2003. The thinning has been as large in the accumulation zone as at the terminus, indicating no point to which this glacier can retreat and achieve equilibrium with the present climate. However, the glacier is quite thick, and will take 50-100 years to melt away. This glacier is oriented to the south and fed by avalanches from the Upper Curtis Glacier and the southwestern flank of Mt. Shuksan. This allows it to survive in a deep cirque at just 5600 feet. Because of its heavy accumulation via avalanching the glacier moves rapidly and is quite crevassed at the terminus. Image below is a 2009 sideview, note the annual dark layers in the ice. The number of crevasses in the nearly flat main basin of the glacier has diminished as the glacier has thinned and slowed over the last 20 years. The glacier lost nearly all of its snowcover in several recent years 2005, 2006 and 2009. In one month we will back on this glacier investigating its mass balance and terminus position. It is a key glacier this year, as the winter was quite warm yet wet, spring was not. Thus, snowpack was much below average below 5000 feet and likely above average above 7000 feet, where the transition will be is the key. In the google earth images below Lower Curtis Glacier is in the left center. The terminus is exposed bare glacier ice and is heavily crevassed. Typically the terminus loses its snowcover in mid-June. Below the terminus there are frequent ice and rock falls, so it is best not to go below the terminus. For our measurements we need to, but we always finish by 9 am. .

Colonial Glacier Retreat and Hydropower

On February 1, 2010February 1, 2010 By mspeltoIn Glacier Observations7 Comments

Colonial Glacier is on the southwest side of Colonial Peak in the Skagit River Watershed, North Cascades of Washington. The North Cascade Glacier Climate Project has made six visits to this glacier over the last 25 years. 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. As this glacier shrinks the amount of runoff it provides during the summer for hydropower is reduced. 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). The glacier had retreated 80 meters since 1955. In 1985 my first visit to the glacier there was no lake at the terminus. 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 long. 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. Runoff to the Skagit River is impacted directly by the climate change and the resultant retreat of the glaciers. Three notable changes in North Cascade streamflow have occurred.
1) Alpine runoff throughout the North Cascades is increasing in the winter (Nov.-Mar.), as more frequent rain on snow events enhance melting and reduce snow storage Streamflow has risen 18% in Newhalem Creek and 19% in Thunder Creek despite only a slight decrease, 1% in winter precipitation at Diablo Dam, within 5 km of both basins. These basins are on either side of Colonial Glacier.
2)Spring runoff (April-June) has increased in both basins by 5-10% due to earlier alpine snowpack melting.
3)Summer runoff has decreased markedly, 27%, in the non-glacier Newhalem basin with the earlier melt of reduced winter snowpack. In Thunder basin runoff has in contrast increased negligibly, 4%. The difference is accounted for in part by enhanced glacier melting. The observed net loss of -0.52 meters per year in glacier mass spread over the melt season is equivalent to 2.45 cubic meters per second in Thunder Basin, 10% of the mean summer streamflow. This trend of enhanced summer streamflow by reduction in glacier volume will not continue as the extent of glaciers continues to decline.

The lower portion of Colonial Glacier is not moving. GPS readings on both rockpiles on the lower glacier indicated no movement from 1996-2006. In the picture above the lake is still small in 1996, lower right corner and the lower rock pile distant from the terminus. The first two images below are from 2006, the lower rock pile is near the terminus and the last image is 2007 the lake has expanded back to the lower rockpile. Additional rock outcrops have appeared in the midst of the upper glacier that were not present in 1991, indicating this glacier does not have a persistent accumulation zone and will not survive current climate.

Yakutat Glacier Rapid Retreat, Alaska

On December 5, 2009January 13, 2014 By mspeltoIn Uncategorized

The Yakutat Glacier during the 1894-1895 Alaskan Boundary Survey ended near a terminal moraine on a flat coastal outwash plain. By 1906 the glacier had retreated from the moraine and a new lake was forming. Harlequin Lake. Surveys of the terminus of the glacier indicated a retreat of 1 kilometer in that decade. From 1906-1948 the glacier retreated an additional 5 km. From 1948-1958 the glacier retreated 3.6 km. The retreat is evident in comparing the Yakutat B-3 quadrangle, from 1958 photography, and Landsat imagery from 1984, 2010 and 2013. Points A-D are the same in each image and the yellow dots are the terminus. In 1984 the terminus was just retreating from a peninsula marked A, the valley at D was filled with ice, there was no break in the surface at C and B was well inland of the terminus. By 2010 the glacier had retreated from A, the valley at D was deglaciated, a small strip of bedrock-sediment was exposed at C from what had been beneath the glacier, and B was still well inland of the terminus. By 2013 the northern arm of the glacier had retreated 6.4 km from the peninsula at A toward the peninsula at B. The central arm of the glacier toward C had retreated 7.5 km and the retreat on the southern edge of the glacier was 6.5 km. The glacier had retreated on average more than 6.6 km in 30 years, a rate of 220 m/year. The retreat was most rapid from 2010-2013, when the glacier retreated 3 km.
Yakutat terminus map

1987 Landsat image

2010 Landsat image

2013 Landsat image.

Today the glacier is the focus of a study by the University of Alaska, led my Roman Motyka, Martin Truffer and Chris Larsen
They have set up a time lapse camera to record frontal changes. The goal is to understand the controls on calving into Harlequin Lake of this glacier. More amazing than the retreat has been the observed thinning of the glacier. The glacier has thinned by more 200 m on average according to the preliminary thickness change maps from the UAF project (Truessel et al 2013). The Yakutat Glacier does not have a high accumulation zone and the recent increase in the snowline elevation and thinning of the glacier have led to a substantial shrinking of the accumulation zone and thinning of the glacier in the accumulation (Truessel et al 2013). This glacier does not have a persistent significant accumulation zone and cannot survive (Pelto, 2010). For a calving glacier to be in equilibrium it needs to have at least 60 % of its area snowcovered at the end of the summer. The glacier is in the midst of a large ongoing retreat. The retreat rate and calving mechanism is similar to that of Grand Plateau Glacier, Bear Lake Glacier and Gilkey Glacier. However, unlike these Yakutat Glacier lacks an accumulation zone, a better analog is East Novatak Glacier, which also has a lower elevation accumulation zone.