Sarqardliup Sermia Supraglacial Lakes

On July 2, 2012July 3, 2012 By mspeltoIn Glacier Observations11 Comments

The progression of supraglacial lakes on the surface on particularly the western side of the Greenland Ice Sheet during the course of the melt season illustrates key processes. In this post we are looking at lakes on the surface of the ice sheet just south of Jakobshavn inland of the Sarqardluip Sermia terminus. Box and Ski (2007) surveyed over 300 lakes in this region and found that the maximum volume occurred close to June 24 during the 2000-2005 period. The image below is from their study, lake F and C from this post are also evident in their figure. They further used the water color to determine depth, corroborated by field work, indicating a maximum depth of 12 m and a mean depth of 4 or 5 m. Sundal et al (2009) examined several regions including this same area for lake evolution and found that below 1000 m peak lake area was June 6, between 1000-1200 m June 17, bweteen 1200-1400 m, June 24th and above 1400 m July 18th. Further they found that 90% of the lakes had drained by August 18th, with drainage peaking below 1000 m in late june, from 1000-1200 m in early July and from 1200-1400 m in late July. The evolution and drainage is well illustrated by a figure from the Sundal et al (2009) paper.. Liang et al (2012) provide an excellent view of how often the lakes occupy the same location, it is evident in their figure that most of the large lakes reform the majority of the years, red and white lakes form more than 60 % of the years. This tendency is what Box and Ski (2007) noted that many lakes refill the same topographic depression each year. This topographic depression is the result of flow dynamics of the ice sheet in some cases resulting from bed topogpaphic changes. Below is a sequence illustrating the development of lakes from June 2012 using MODIS and Landsat imagery. The Landsat images are from June 2 and June 19 the arrows and letters indicating specific locations. Note the shift in the main lake formation area from the light green to the dark green arrows. The light green arrows are below 1000 m and the dark green from 1200 to 1300 m, except for lake A which has persisted. Most of the lakes below 1000 m from June 2 are gone by June 19. The same area is also seen in 2005 with some of the same lakes filled The MODIS images are from June 2 and June 30 and again indicate the shift in location of the supraglacial lakes. The lakes evident below 1000 m are almost all gone by the June, and few lakes exist except above 1200 meters, indicating an earlier melt cycle this year. The location of Tiningnilik Lake is also shown, and it has filled somewhat during the month, being the recipient of some of the water from lake drainage events. This is indicative of the progression of the melt season and the development of the hydrologic drainage system. As the melt season begins snowmelt first percolates into the snowpack and can refreeze. After the snowpack has warmed meltwater percolates quickly through the snowpack and gathers into streams and lakes on the glacier surface. The higher the elevation the deeper the snowpack to be warmed and the colder the temperatures further delaying the melt process. Hence, the melt progression with elevation. I have found the lakes to be useful for navigation purposes days to day on the ice sheet, but the lakes do not tend to persist long, most draining within a few week of formation. The drainage of lakes indicates the maturation of the drainage system beneath the ice sheet that takes the water to the margin. The volume of water released is immense, and initially the meltwater would exceed the capacity of the drainage system leading to high basal water pressure which can enhance sliding for a short period (Zwally et al 2002). However, after the drainage system is developed water pressure falls and velocity does dramatically as well, the net impact of the brief acceleration is not large on the mean annual velocity as noted by Sundal et al (2011), but the increased meltings has led to an overall decline in flow speed as the hydrologic system matures over a shorter period. Luthje et al (2006) found that the number of supraglacial lakes is largely controlled by topography and enhanced melting should not increase their number. What will be important is to continue to examine changes in timing of formation and drainage, distribution of the lakes and volume of the lakes. For 2012 the drainage of almost all lakes below 1200 meters by June 30 is an early loss of lake area.

Glacier Post Index 2009-2012

On July 1, 2012 By mspeltoIn Glacier Observations

Glacier Index List
Below is a list of the individual glacier posts examining our warming climates impact on each glacier. This represents the first 3 years of posts, 208 total posts, 194 different glaciers. I have worked directly on 43. The others are prompted by fine research that I had come across, cited in each post or inquiries from readers and other scientists. I then look at additional often more recent imagery to expand on that research. The imagery comes either from MODIS, Landsat, Geoeye or Google Earth.

New Zealand
Tasman Glacier
Murchison Glacier
Donne Glacier
Mueller Glacier, NZ
Gunn Glacier, NZ

Africa
Rwenzori Glaciers
Tyndall Glacier, Kenya

Himalaya
Ngozumpa Glacier, Nepal
West Barun Glacier, Nepal
Samudra Tupa, India
Zemu Glacier, Sikkim
North Lhonak Glacier, Sikkim
Theri Kang Glacier, Bhutan
Zemestan Glacier, Afghanistan
Khumbu Glacier, Nepal
Imja Glacier, Nepal
Gangotri Glacier, India
Milam Glacier, India
Satopanth Glacier, India
Kali Gandaki Headwaters, Nepal
Menlung Glacier, Tibet
Boshula Glaciers, Tibet
Urumquihe Glacier, Tibet
Sara Umaga Glacier, India
Dzhungharia Alatau, Kazakhstan
Petrov Glacier,Kyrgyzstan
Hailuogou Glacier, China
Reqiang Glacier Retreat, Tibet
Himalaya Glacier Index

Europe
Taconnaz GLacier, France
Mer de Glace, France
Dargentiere Glacier, France
Grand Motte and Pramort Glacier Tignes Ski area, France
Saint Sorlin, France
Sommelier Glacier
Obeeraar Glacier, Austria
Ochsentaler Glacier, Austria
Pitzal Glacier, Austria
Dosde Glacier, Italy
Maladeta Glacier, Spain
Presena Glacier, Italy
Triftgletscher, Switzerland
Gietro Glacier, Switzerland
Rotmoosferner, Austria
Stubai Glacier, Austria
Hallstatter Glacier, Austria
Ried Glacier, Switzerland
Cavagnoli Glacier, Switzerland
Chuebodengletscher and Ghiacciaio-del-Pizzo-Rotondo
Forni Glacier, Italy
Careser Glacier, Italy
Peridido Glacier, Spain
Engabreen, Norway
Midtdalsbreen, Norway
Tunsbergdalsbreen, Norway
TungnaarJokull, Iceland
Langjökull, Iceland
Gigjokull, Iceland
Skeidararjokull, Iceland
Kotlujokull, Iceland
Lednik Fytnargin, Russia
Rembesdalsskaka, Norway
Irik Glacier, Mount Elbrus, Russia

Greenland and European Arctic
Mittivakkat Glacier
Ryder Glacier
Humboldt Glacier
Petermann Glacier
Kuussuup Sermia
Tiningnilik Glacier Lake
Jakobshavn Isbrae
Umiamako Glacier
Kong Oscar, Glacier
Upernavik Glacier
Epiq Sermia
Sortebrae Glacier, Greenland
Severnaya Zemlya, Russian Arctic
Hansbreen, Svalbard
Nannbreen, Svalbard
Hornbreen and Hambergbreen, Svalbard
Albrechtbreen, Svalbard
Roze and Sredniy Glacier, Novaya Zemyla
Nizkiy and Glazova Glacier, Novaya Zemyla

South America
Colonia Glacier, Chile
Artesonraju Glacier, Peru
Nef Glacier, Chile
Tyndall Glacier, Chile
Alemania Glacier, Chile
Zongo Glacier, Bolivia
Sierra Nevade del Cocuy Glaciers, Colombia
Ritacuba Blanco Glacier, Colombia
Llaca Glacier, Peru
Joerg Montt Glacier, Chile
Arhuey Glacier, Peru
Seco Glacier, Argentina
Onelli Glacier, Argentina
Quelccaya Ice Cap, Peru
Glacier Gualas, Chile

Antarctica and Circum Antarctic Islands
Pine Island Glacier
Fleming Glacier
Hariot Glacier
Smith Glacier, Antarctica
Amsler Island
Stephenson Glacier, Heard Island
Neumayer, South Georgia
Ampere, Kerguelen
Cook Ice Cap, Kerguelen Island
Nordenskjold Coast, Antarctic Peninsula
Prospect Glacier, Antarctic Peninsula
Ross Hindle Glacier, South Georgia
Vega Island Ice Cap
Rohss Bay, James Ross Island, Antarctica

North Cascade Glacier Climate Project Reports

Forecasting Glacier Survival
North Cascade Glacier Mass Balance 2010
Columbia Glacier Annual Time Lapse
North Cascade Glacier Climate Project 2009 field season
28th Field Season Schedule of the North Cascade Glacier Climate Project
North Cascade Glacier Climate Project 2011 Field Season
BAMS 2010
2011 Glacier mass balance North Cascades and Juneau Icefield
Taku Glacier TSL Paper

Sourdough Glacier Retreat, Wind River Range, Wyoming

On June 26, 2012June 27, 2012 By mspeltoIn Glacier Observations

Sourdough Glacier descends the north side of Klondike Peak in the Wind River Range of Wyoming. Thompson et al (2011) identified the loss in area of Wind River Glaciers from 1966 to 2006. The total surface area of the 44 glaciers was estimated to be 45.9 km2 in 1966 and 28:6 km2 in 2006, a decrease of 42%. The retreat has varied from substantial on Minor and Grasshopper Glacier to limited on Upper Fremont Glacier. For Sourdough Glacier the 1966 USGS map of the area based indicates the glacier ending in a small lake, orange line in images. We use 1994, 2006 and 2009 images in Google Earth to examine the glacier changes. By 1994 (green line) the glacier had retreated 160 meters and the lake nearly doubled in size. By 2006 (magenta line) retreat from 1966 was 280 meters with a more pronounced calving face developing. In 2009 the calving face remains and the glacier had retreated another 20 meters overall, 40 meters in the glacier center. The increased height of the calving face suggests the lake is deeper than at the 1994 terminus position and that the lake will continue to expand with further retreat. The calving front and slope of the glacier is similar to Lyman Glacier. The retreat from 1966-2006 is a 20% reduction in overall glacier length. If a glacier lacks a persistent accumulation zone it will not survive (Pelto, 2010). The key indicator of a glacier without a consistent accumulation zone if retreat of the upper margin of the glacier and emergence of rock outcrops on the upper glacier. There are some limited changes of this nature on Sourdough Glacier, but most of the change has been at the terminus. The forecast for survival of Sourdough Glacier is not as clear cut as on Minor and Grasshopper Glacier. The crevasses indicate the glacier is still actively moving.

Pedersen Glacier Retreat Lake Expansion, Alaska

On June 23, 2012June 23, 2012 By mspeltoIn Glacier Observations2 Comments

Pedersen Glacier is an outlet glacier of the Harding Icefield in Kenai Fjords National Park near Seward, Alaska. The glacier drops quickly from the plateau of the icefield through a pair of icefalls terminating 3.5 km in a lake at 25 meters. Bruce Molnia of the USGS as part of an effort in repeat photographs of Alaskan glaciers to show historic changes captures the changes of Pedersen Glacier. A photographic pair taken from about the same shoreline location of Pedersen Glacier. The photographs identify significant changes that have occurred during the 95 years between 1909 and 2004. The 2004 photograph a 1.5 km retreat of Pedersen Glacier from the field of view. In a recent study of the glaciers, by NASA and the NPS, (Hall et al, 2005) identify the retreat of the glacier as slow but steady from 1973-1986 at 510 m (35 m/a) and 110 m (8 m/year) from 1986-2000. Here we compare a 1994 Landsat, 2005 Google Earth, 2010 Landsat and 2011 Google Earth imagery illustrating a rapid increase in retreat rate from the previous periods. The red line in the Google Earth images is the 1994 terminus, the green line the 2005 terminus and the orange line the 2011 terminus. In 1994 the lake at the terminus is small and not continuous across the ice front (top image), the green dots are the terminus and the burgundy dots the snowline on the date of the image, near the top of the icefall. In the second image from 2005 the lake is now well developed but the number of icebergs in the lake limited. The third image from 2010 indicates a rapid lake expansion which is now largely filled by icebergs. In 2011 the lake remains filled with some very large icebergs indicating the recent nature of terminus collapse in the lake. The retreat from 1994-2005 was 450 meters (40 m/year) and 650 meters from 2005-2011,(110 m/year). The snowline is somewhat above the top of the icefalls on Pedersen Glacier. .. A closeup view of the terminus area from 2005 and 2011 indicate that the lake has more than doubled in size since 1994, and there is no distinct change in glacier width or surface elevation to suggest the glacier is near a point where the rapid terminus retreat will end. The glacier follows the pattern of nearby Bear Glacier, Yakutat Glacier, Gilkey Glacier and the predicted impending retreat of Brady Glacier.

Great Glacier Retreat, Stikine Icefield, BC Canada

On June 20, 2012 By mspeltoIn Glacier Observations2 Comments

Great Glacier is the largest outlet glacier of the Stikine Icefield terminating in Canada. The name came from the large expanse of the glacier in the lowlands of the Stikine River during the late 19th and early 20th century, that has now become a large lake. The glacier filled what is now a large lake at the terminus of the glacier pushing the Stikine River to the east side of the valley. In 1914 the glacier was easy to ascend from the banks of the Stikine River, the picture below is from the National Railroad Archive. By 1965 the new lake had formed, but the glacier still reached the far side of the lake in several places as indicated by the 1965 Canadian Topographic Map, green arrows. A comparison of 1986 Landsat, 2005 Google Earth and 2011 Landsat imagery illustrates the retreat. The yellow arrow indicates a glacier dammed lake, the violet arrows the snowline and the red arrow the northeast tributary. By 1986 the new lake had largely developed, and the glacier was beginning to retreat into the mountain valley above the lake. Retreat from the moraines of the late 19th century was 3200 m. By 2011 the glacier had retreated further into valley, 900 m retreat from 1986-2011. Great Glacier is following the pattern of behavior of other Stikine Icefield glaciers such as Sawyer Glacier There is a glacier dammed lake that has to date changed little at the yellow arrow, this lake fills and drains under the glacier periodically, top image below. A view of the glacier from across the lake today indicates the distance to the now valley confined glacier, and the trimlines of the former ice surface, yellow arrows in middle image The Great Glacier has one major tributary on the northeast tributary that is very low in elevation with a top elevation of 800 m. Given the regional snowline of 1100-1200 meters (Pelto, 1987)this is too low to retain snowcover through the summer and will lead to progressive thinning. This branch of the glacier has and will thin faster than the rest of the glacier and is doomed given its limited top elevation. The proglacial lakes on its periphery will continue to grow as this downwastes, green arrow bottom image.

Suiattle Glacier Retreat and Outcrop Emergence, North Cascades

On June 17, 2012June 17, 2012 By mspeltoIn Glacier Observations

C.E. Rusk in 1906 hiked right to the terminus of Suiattle Glacier, which is labelled Lion’s Paw in Rusk (1924). The glacier had retreated 1400 m since its Little Ice Age maximum and based on the lack of reported brush below the glacier, this retreat had occurred primarily in the previous 30 years. By 1940 the glacier had retreated another 900 m back to within 120 m of its current position. Suiattle Glacier retreated more from its LIA maximum than any other glacier in the area, probably due to the low slope of the Suiattle Valley, from 1550-1700 m, down which the glacier had advanced. Rusk, noted the lack of any terminal moraine near the end of this glacier, this was unusual in his experience. In other words typically in this period a terminal moraine was not too distant from the current termini position. This glacier had already retreated so far that the terminal moraine was not only well down valley, but buried by aggrading sediments from the glacial stream. This retreat continued until 1967, below is a 1967 photograph of the glacier from Austin Post (USGS).
Between 1967 and 1979 Suiattle Glacier stopped retreating and began a small advance. Suiattle Glacier advanced 15-20 m during the 1970’s. Our visit in 1988 to the glacier indicated retreat had just begun, and by 1995 the glacier had retreated only 28 m from 1988 to 1995 (top image). The retreat than accelerated with another 150 m of retreat by by our 2002 survey. The terminus remained crevassed steep and convex through 1995 forcing us to the eastern margin to reach the terminus. By 2002 (second and third image) the terminus was no longer that steep or crevassed and we could walk right down the middle. The overall retreat of this glacier as seen in the Google Earth imagery sequence of 1998, 2006, 2009 and 2011 indicate the retreat with the brown line being the 1985 terminus, the green line the 1998 terminus, the orange line the 2006 terminus and the red line the 2009 terminus. Total retreat from the advance moraine of the 1970’s is 270 m. What is a more important reflection of the is glaciers current state is the thinning that is apparent. Outcrops of rock are emerging as the glacier thins even well above the terminus (A-E). The majority of the outcrops are on the eastern side of the glacier. Even after a year of good positive mass balance for the glaciers in 2011, the outcrops remain exposed. The upper portion of the glacier appears robust still. Unlike its counterpart over the glacier gap on its western margin where the west arm of the Whitechuck Glacier melted away.
On Suiattle Glacier in 2002 we undertook a detailed ice worm study, setting up six square meter plots and counting the ice worms. The recorded mean density was 1800 to 2600 ice worms per square meter in 2002. With an area of 2.7 square kilometers, this represents 5-7 BILLION ice worms on this glacier! This is comparable to the earth’s entire human population on just one glacier. Good thing they do not use many natural resources each. This is also the highest population we have identified in the North Cascades. The picture below is from this survey, the quality is tough because they only come out in low light and this was prior to having a digital camera.

Tiningnilik Glacier Lake, Greenland

On June 12, 2012July 15, 2012 By mspeltoIn Glacier Observations

Tininglilik ( also-Tininnilik) is a glacier dammed lake onn the southern margin of the Sarqardliup Sermia 30 km south of Jakobshavn Glacier. I first examined this lake during the UMaine research program on Jakobshavn in 1985. The lake periodically drains and refills over an approximate 10 year period. The lake has an area of 43 square kilometers when full and 20 km2 when empty, each emptying phase releases 2-3 cubic kilometers of water. The lake is filled mostly by subglacial input derived from surface melt, much from supraglacial lake drainage, which makes June and July the main months for refilling. The lake drainage and refilling in 1993 and 2003 was examined by Furuya and Wahr (2005). They expanded on the work of Roger Braithwaite and Henrik Thomsen who had identified five lake drain-fill cycles from 1945-1983. In discussing this with them in Norway in 1986 I noted that the lake was not yet refilled, three years after the last drainage. They suggested that the lake had always filled relatively slowly and drained quickly. After the 1993 discharge 1997 fieldwork noted the lake was still not close to full. A 2000 Landsat image (first image) indicates the lake full, with the yellow and red arrows indicating key locations for differentiation when the lake is drained and filling. After the 2003 drainage, by 2005 the lake had filled somewhat (second image), in 2007 (third image) the lake is 70% full in terms of area and by 2009 the lake was full (fourth image). In the 2005 image the former lake elevation is seen as a sharp transition from pink to green, this is the lake trimline. The lake drained between the June 14 (top) and August 19th (middle) Landsat images from 2010, so lake drainage occurs in a matter of weeks. A further image from July 2011 indicates the slow rate of refilling of the lake. By June 12 2012 the lake is still not occupying the north trending arm at the red arrow (last image), this is a MODIS image and lacks the clarity of the Landsat images.The main terminus of Sarqardliup Sermia has retreated 200 meters from 2000-2010 after exhibiting no trimline or significant retreat in the previous 50 years. The marginal changes of Sarqardliup Sermia as evidence by the lack of trimline are small compared to most areas around the Greenland Ice Sheet. As the ice sheet in the region thins at some point it will no longer dam Tiningnilik to the same level. Will the lake fill completely again this time? The 2010 fill limit was very close if not the same as previous levels, however, the seven year time for the refill was the fastest yet. Since this was not due to a lower level is this due to the record ice melting of the 2003-2010 period? There are two notable changes in the position of the terminus that ends in Tiningnilik at the green arrows from the 2000 to the 2010 image. There has been a 300 to 500 meter retreat of the terminus in these two locations and this could lead to greater calving and further retreat as this secondary terminus bed becomes deeper as it retreats toward the valley filled by the Sarqardliup Sermia. This would lower the outlet level of Tininglnilik, suggesting that the current refill will not be as high as previous lake fillings. The critical elevation is that of the bottom of the ice, the lower this is, the greater the hydrologic pressure for a given lake level and the lower the exit elevation is once a drainage path is established. In the intervening month melt rates have been high and the rate of infilling of Tiningnilik has been amazing as seen in the last image from July 14, 2012. To the south this has led to amazing flows in Watson River. <

Devon Ice Cap Northern Outlet Glacier Retreat

On June 9, 2012June 9, 2012 By mspeltoIn Glacier Observations1 Comment

The Devon Ice Cap on Devon Island in the Canadian Arctic ice cap’s area has an area of 15,000 km2, with a volume of 3980 km3. The ice cap area decreased by 600 km2 (4%) between 1960 and 2000 (Sharp et al, in press). The ice cap has been the focus of an ongoing research program led by the University of Alberta Arctic and Alpine Research Group and Natural Resources Canada in Ottawa. The mass balance from 1960-2009 has been cumulatively -5.6 m, with nine of the eleven most negative years occurring since 1998. The Devon Ice Cap’s negative balance has been due to warming and greater ablation, as the upper part of the glacier has seen some increase in accumulation, which has been more than offset by increased melting ( Sharp et al, 2011). Belcher Glacier is the the principal outlet glacier calving up to 40% of the total iceberg volume from the ice cap. Belcher Glacier and its neighbor Unnamed5 Glacier are the focus of this post. A recent study by Van Wychen et al (2012) focused on velocity changes of the Devon ice Cap. The fastest velocities of 200-250 meters/year are at the front of the Belcher Glacier. A comparison between Belcher Glacier’s velocity from the 1991-2000 period and 2009 indicate that Belcher Glacier velocity has declined at the glacier front recently, which has likely aided the glacier in slowing retreat, an excellent time lapse gives a sense of the dynamics. Here we used 1998 (top), 2008 (second image) and 2010 Landsat imagery(bottom image) combined with Geoeye imagery (third image)from 2010 to identify changes in glaciers adjacent to the Belcher Glacier. To the north of Belcher Glacier a small nunatak is evident at the red arrow. This nunatak is 500 meters inland from the terminus in 1998 and is at the terminus in 2010. The orange arrow indicates the terminus of a land terminating glacier which in 1998 reached a small inlet in the peninsula emerging from under the ice cap. By 2010 the glacier has pulled back 250 meters from this inlet. The yellow arrow indicates the terminus change of Unnamed5 Glacier. The glacier has pulled back to the base of a zone of intense crevassing between 1998 and 2010 a retreat of 500 m. The next glacier to the east in 1998 has a 600 meter wide margin in the ocean. By 2010 the glacier front is in contact with the ocean for less than half this length. . Further to the east from Belcher and Unnamed5 Glacier there is a set of three islands that are losing contact with the Devon Ice Cap between the 1998 Landsat and 2009 Geoeye imagery, violet arrows 2009. The losses paralell those from other Canadian Arctic glaciers, Penny Ice Cap.

Gietro Glacier Retreat and Hydropower, Switzerland

On June 5, 2012June 21, 2012 By mspeltoIn glacier climate change, Glacier Observations, switzerland glacier retreat3 Comments

Gietro Glacier may sound like a type of italian dessert, but this glacier has a deadly history. During periods of advance the glacier blocked off the valley of Mauvoisin. Failure of the glacier ice dam led to large flood events in 1595 and 1818 that lead to the loss of many lives in the valley below. Today the Mauvoisin Dam one of the 10 largest concrete arch dams in the world not only provides hydropower but also protection against this hazard. In 1818, an advance of the Gietro glacier, now retreated high above the reservoir, generated ice avalanches which blocked the flow of the river. When the ice barrier was breached, 20 million cubic meters of flood water was released devastating the valley (Collins, 1991).There are several other large glaciers in the basin Otemma, Mont Durand and Brenay that provide runoff to power what is today a large hydropower project. The Mauvoisin Dam can produce 363 MW of power, and typically provides 1030 millionKWh of power each year. The reservoir can store 200 million cubic meters of water. Erosion largely from the glaciers in the watershed produce enough sediment to cover the lake bottom with 60 cm of sediment per year (Loizeau, et al. 2010). Gietro Glacier is one of the glaciers where the terminus is monitored annually by the Swiss Glacier Monitoring Network (SCNAT). The glacier advanced 150 m from 1962-1985. Retreat from 1985 to 2000 was 110 m or 7.5 m/year, accelerating to 275 m from 2000-2010, 27.5 m/year. This post focuses on comparison of a 1988 Landsat image, 2001 terminus photograph from the SCNAT and 2009 Google Earth imagery. In 1988 the glacier terminates at the top of a steep cliff that is evident in the 1988 image, yellow arrow, dam is burgundy arrow. By 2001 the glacier has retreated to the first prominent joint feature, green arrow, on the north side of the glacier above the cliff, still yellow arrow. In 2009 the terminus is indicated by a blue arrow. A limited area above the terminus is stagnant an area that is 200 m by 150 m, red arrow. Above this point the glacier has been thinning, but still remains active as indicated by the crevassing. . The glacier in 2009 has very limited snowcover by the end of the summer. A glacier to thrive should be 60% snowcovered at the end of the melt season, in this case it is less than 20%, green dots mark the main snowline below. The lack of snowcover indicates a negative mass balance that is driving the retreat. If the glacier consistently loses most of the accumulation zone snowcover it cannot survive (Pelto, 2010). In the Swiss Glacier Inventory(Kääb et al, 2002), noted a 21% loss in glacier area from 1973-1998, with almost all the change occurring after 1985. The retreat if this glacier is similar to that of other Swiss glaciers, Ried Glacier and Triftgletscher

Jorge Montt Glacier Retreat

On May 31, 2012May 31, 2012 By mspeltoIn Glacier Observations

The Jorge Montt Glacier is one of the main tidewater glaciers of the Southern Patagonia Icefield. The glacier has been the focus of ongoing annual observations by the Laboratorio de Glaciologia at the Center for Scientific Studies, University of Chile. Two recent papers highlight the dramatic changes this glacier is undergoing. The glacier has retreated 19.5 km from 1898-2011 (Rivera et al, 2012a). A recent photograph of the terminus from Andrés Rivera indicates the extensive crevassing and calving of icebergs indicating the high very high velocities.. The velocities were determined from tracking of salient features for an 11 month period using time lapse photography and indicated a mean velocity of 13 meters/day, with maximum velocities of up to 33 meters/day, in the center of the glacier (Rivera et al, 2012b). These velocities rival the high velocities on the faster Greenland outlet glaciers and San Rafael Glacier, Chile. They did not observed seasonal velocity changes. This paper provides a nice visual of the velocity, top image. The velocity and retreat tend to increase when water depth increases. The mean water depth at the calving front has declined from over 260 m 1997-2003 to closer to 220 m 2003-2011, bottom image indicates the water depths from Rivera et al (2012a). . . A map of the long term retreat of the glacier is provided in both papers, here we examine a closeup view of the lower glacier from Landsat imagery in 1997, 2003 and 2011. The glacier retreat peaked during the 1990-2000 period with 8.5 km of retreat. The lake widened and deepened at the calving front for that period. The yellow arrow indicates the 1997 terminus, burgundy arrow 2003 and orange arrow 2011. The green arrows point the expansion of exposed bedrock areas on the east margin of the glacier from 1997-2011. Retreat from 1997-2003 was 2250 m, 375 m/year. Retreat from 2003-2011 was 2000 meters, 250 m/year. In 2011 an additional nunatak has emerged as the glacier has thinned. The 2011 terminus is near a point where the lake appears it will widen again, the potential depth is hard to assess. The map from Rivera et al (2012a) indicates at least a short term deepening at the ice front, this is at the same point as a modest lake width reduction. . Below is a closeup of the changes 12-14 km upglacier of the terminus indicating the rapid thinning from 2003 to 2011 expanding the bedrock exposed at point B and exposing the new nunatak at Point C. The retreat of this glacier follows the regional pattern observed by the Laboratorio de Glaciologia on other glaciers such as Gualas Glacier, Nef Glacier, Alemania Glacier, Tyndall Glacier and Colonia Glacier.

Aguja and Ritacuba Blanco Peak Glacier Retreat, Colombia

On May 28, 2012 By mspeltoIn Glacier Observations

The Sierra Nevada del Cocuy is the second largest concentration of glaciers in Colombia. The glaciated area in Colombia is at 6º30′ N and 72º20′ W and extends along the crest of this range. Morris et al (2006) documented the decline in total area from 39.1 square kilometers to 16.3 square kilometers in 2003. Poveda and Pineda (2009) estimated glacier area of as 28.6 km2 in 1989, 22.9 km2in 2000, and 17.00 km2 in 2007. A 40% decline in area in two decades. This post follows up on an earlier post that examined changes in southern half of the glaciated range. This post looks at the glaciers at the northern edge of the range using Landsat images from 1988 and 2012 and a Geoeye image from 2009. The glaciers are on the flanks of Ritacuba Blanco Peak and Aguja Peak, inside the burgundy circle in the map below. The image below is a combined Landsat image with a 1988 image on top and a 2012 image below. Each arrow is a different color and number, pointing to the same glacier or feature. Glaciers 1-3 are on the east flank of Aguja Peak, Glacier 4 on the norhwest side of Ritacuba Blanco. In 1988 glaciers 1-4 have respective areas of: 1=0.3 km2, 2=0.4 km2, 3=1.1 km2 and 4=0.35 km2. By 2012 the areas are: 1=0.05 km2, 2=0.2 km2, 3=0.5 km2 and 4=0.08 km2. Glaciers 1 and 4 are nearly gone. Glacier 1 and 2 exhibit limited snowcover, lighter blue, indicating a lack of accumulation, and even short term survival is not possible (Pelto, 2010). Glacier number 5 and 6 are on the west side of Ritacuba Blanco. In 1988 the two main glaciers end near the margin of recently formed lakes indicated by the blue and orange arrows. By 2012 retreat from the the margin of these lakes exceeds 500 meter in both cases. For glaciers that were less than 1500 meters long, this is a substantial retreat. An additional view of the region is provided in Google Earth and Glacier 5 is seen at the northern edge of a Geoeye image from 2009. Indicating the distance of retreat from the lake near the 1988 glacier margin. Both glaciers on the west flank of Ritacuba Blanco exhibit consistent snowcover presence on their upper reaches above 5000 meters, indicating they have the potential to survive current climate at a reduced size. An expedition to the mountain and the glacier indicate what the area looks like. The bottom image is from a 2012 expedition to Ritacuba Blanco

Deming Glacier Terminus Retreat

On May 24, 2012June 11, 2013 By mspeltoIn Glacier Observations1 Comment

The reduction in width and crevassing in the Deming Glacier Icefall indicates a reduced flow into the terminus reach of the Deming Glacier. This post examines the retreat of the Deming Glacier from 1984-2010. The glacier has retreated significantly as have all 47 glaciers we observe in the field. The retreat parallels that of other Mount Baker glaciers, Boulder Glacier and Easton Glacier (Pelto,2006). Each year since 1990 we have been able to observe the terminus of the Deming Glacier from afar at our survey point. Only in two years have we actually visited the terminus 1996 and 2002. The latter proved hazardous enough to discourage further attempts. Deming Glacier advanced dramatically during the 1950’s and did not retreat substantially until the late 1980’s. The first set of images are from the survey point in 2003, 2006, 2007, 2008 and 2010. The yellow arrows indicate the narrowing of the debris free section of ice in the middle of the glacier. The red arrows indicate the moraines from the advance ending around 1980 including the lateral moraines and two sets of terminal moraines. The closer set of terminal moraines is where the glacier ended in 1996 when we visited the glacier. Both the lateral and end moraines are indicated. The stream issuing from the glacier front feeds the Middle Fork Nooksack River, which supplies some of Bellingham, WA water supply. We conducted a . The next set of images include a 1979 Austin Post USGS image from 1979 and the rest are from the Google Earth showing in order the 1984 map position (blue), 1994 terminus (magenta), 2006 terminus (green) and 2011 terminus (yellow). Note similarity of blue line and 1979 terminus. The glacier retreated 160 m from 1984-1994, 16 meters/year. From 1994 to 2006 the glacier retreated 240 m, 20 meters/year. From 2006-2011 the glacier retreated 120 m, a rate of 24 meters/year. The rate is still on the increase. The top image in the sequence below is a view from 2002 showing the end of the glacier (survey point from red X. The front was still steep at the time and the width of the debris near the terminus limited, clean ice width is 200 m.. By 2011 the terminus is not nearly as steep and most of the glacier width is debris covered. The view in Google Earth imagery from 1998 and 2011 indicates the change and the survey point is indicated by the red x. The last image is a 2011 closeup view in Google Earth the debris free ice section is 40 meters wide. What is causing the narrowing of the debris free ice is the reduction in velocity, the increased thinning of the clean ice in the center compared to the insulated debris covered ice at the edges. As the elevation difference increases debris slides off the side of the developing debris covered ridge (Pelto, 2001: 35).