In Glacier National Park, MT all glaciers have been retreating. From 1850 to the present the number of glaciers has been reduced from 150 to 25. There are a few glacier such as Old Sun Glacier that have been retreating quite slowly since 1966 when the USGS maps were completed and are not disappearing anytime soon. Old Sun Glacier faces northeast and terminates at 8200 feet. This is a higher altitude than the rapidly shrinking Sperry Glacier, 7600 feet or Grinnell Glacier 6600 feet. A comparison of Google Earth images of Old Sun Glacier from the 1966 USGS map to 2009 indicate that the glacier has thinned and retreated but the majority of the glacier remains. The loss of area was noted as 12% from 1966-2005 and 14% by 2009. Below is the 1966 image, 1991 image, the strong brown line is the 1991 margin, 2003 image, 2005 image and the last two are 2009 images. 
The upper section of the glacier retains accumulation even in the poorest years such as 2009 and the glacier remains crevasses. The number of crevasses, slow recession and healthy accumulation zone point to a glacier that with present climate can be forecast to survive Pelto (2010). As long as a glacier maintains an accumulation zone it can survive at a reduced size. There are seven glaciers in Glacier National Park that have a consistent accumulation zone today each of these as a result is diminishing slowly,compared to the majority that have and will soon disappear.
Month: March 2011
Colonia Glacier Retreat and Glacier Lake Outburst Floods
Colonia Glacier drains east from the Northern Patagonia Icefield feeding the Baker River, Chile. The recent substantial retreat of Colonia Glacier like Glacier Nef just to its north is posing new hazards. The glacier is unusual in the number of lakes that are adjacent to or feed into the adjacent glacier damed or proglacial lakes. In the image below Lake A=Arco Lake, Lake B=East Terminal Lake, Lake C=Cachet 1 , Lake D= West terminal Lake, Lake E=Colonia Lake and Lake F=Cachet 2. 
The glaciers recent retreat and glacier lake outburst floods have been closely monitored by the Laboratorio de Glaciología in Valdivia, Chile.Aniya and others (1999)observed that Colonia Glacier began a rapid retreat after 1985
Superimposition of a RADARSAT image from 1997 and a Landsat 1987 image indicated a retreat of
400 m, from 1997-2005 the retreat has further accelerated, with a general frontal retreat of 2.5 km. 
Rivera and others (2007) observed that the Colonia Glacier had lost 9.1 square kilometers of area from 1979-2001, which is 3% of the total glacier area. The Laboratorio de Glaciologia’s
In the spring of 2008 Baker River suddenly tripled in size, in less than 48 hours, roads, bridges, and farms were severely damaged. Lake Cachet 2 had vanished the 5 square kilometer glacial lake had emptied 200 million cubic meters of water in just a matter of hours. This lake drained beneath the glacier after sufficient water had filled the lake to buoy part of the glacier and subglacial conduits had begun to develop. Since Cachet 2 emptied in April 2008, the lake has emptied five more times October,
December 2008, March and September 2009 and March 2010, with peak flows released of 
3000 cubic meters per second. Below are images of Cachet 2 half- full in Google Earth Imagery from Sept 2008 (note trimline above lake), and full after the flood on 5/28/2008 and empty on 4/8/2008, and lastly the image of the Colonia River’s wide fresh braided stream channel flowing into the Baker River. The newly deposited material from the flood is what makes the wide braided valley such a fresh sediment brown color. 
The two lakes at the terminus of the glacier did not exist in 1979, the western most terminus lake (B) drained into the easternmost terminus lake (D) via a sub-glacial tunnel after formation in the late 1980’s until 2005 when a channel was cut right through the glacier terminus. This is evident in the image below, there is still glacier ice on both sides of this drainage channel. 
The development and demise of glacier dammed lakes and the resultant problem of glacier lake outburst floods is not rare today, Imja Glacier, and Tulsequah Glacier are other examples. In the case of Baker River the outburst floods are a threat to the planned hydropower developments as documented by Dusaillant and others (2009). The Colonia Glacier retreat mirrors that of Glacier Nef the next major glacier to the north. Hidroaysen Project is proposing 5 dams on the Baker and Pascua River generating 2750 MW of power. Glacier Nef retreated 3400 m from 1945-2000, 2400 m retreat of the retreat occurred in the 1994 collapse of the terminus tongue into the proglacial lake, which is now 3.5 km long. This retreat includes that of , Gualas GlacierReichert Glacier, Steffen Glacier, and Nef Glacier.
Boshula Mountains, Tibet Glacier retreat
Increasing number and area of glacial lake in the Boshula Mountains, Tibet. Wang and others (2011) note that Glacial lakes have expanded from 1970-2009 by 19 % and the area that is glacier covered has decline by 13% during the 1970-2009 period in the Boshula Range. An examination of one unnamed glacier in this range illustrates this pattern. The glacier currently terminates at 4820 meters, the top of the glacier is at 5560 meters. 
The glacier terminated at 4660 meter during the Little Ice Age. The glacier has retreated 1950 meters from the evident Little Ice Age moraines and 670 m from the edge of the lake that is beyond the glacier terminus. The glacier was almost to the shore of the lake in 1970 and has retreated 580 meters since then. The glacier was also separated by only a short distance from a tributary glacier that has experienced a 700 meter retreat since 1970, seen in the second image below. By comparing the height of the lateral moraine at the glacier terminus and at 5200 meters the amount of thinning can be identified. 
Thinning of the glacier is 140 m at the terminus and 60 meters at 5200 meters. Melt season temperature and accumulation season precipitation are the key factors in glacier mass balance which translates to glacier terminus behavior. For the Boshula Mountains the main accumulation season is the summer monsoon, which is also lower on the glacier the main melt season. At Bomi 70 km west of the glaciers Wang and others (2011) note that summer precipitation has declined slightly since 1970 while summer temperatures have rise 1 C. It is the rising temperature that has been the key reason for retreat of the glaciers and consequent exposure of new lakes and expansion of older lakes at glacier termini. The frequent summer snowfall on the upper 60% of the glacier prevent surface soot from impacting ablation on the majority of the glacier. Solar radiation is highest during the summer, but soot deposits are at their lowest during the summer monsoon and are also buried over most of the glacier by new snowfall. 
Fits with other Chinese glaciers with a trend becoming increasigly negative for mass balance leading to faster retreat after 1975 Ding and others (2006) The Bushula Range glacier that is focussed on here drains into the Salween River as does the 33, km long Laigu Glacier,seen below,
one of the headwaters of the Salween.
Saywer Glacier, Alaska Retreat
Sawyer Glacier is an Alaskan glacier that many people have observed the retreat of. It is one of three glaciers that calves into Tracy Fjord, that is often visited by cruise ships. The 2.3 km retreat over the last 50 years has made approach to the actual terminus difficult for larger cruise ships. The terminus of the glacier was almost to the main arm of the fjord in 1961, USGS map, blue arrow. The 2003 Google Earth images indicates a 2.3 km retreat, green arrow. 
The green line down fjord marks the 1961 terminus, the upfjord line is at the 1100 foot contour of the USGS map and is parallel with the current terminus location. The snowline of the glacier was noted to be at 1125 meters by Pelto (1987), using Landsat images. At the time usable images were rare. Today images are acquired daily by MODIS and if the weather is clear, which is not common, the snow line is evident. Recent satellite images from 2006 and 2009 indicate the snow line still in the 1100 to 1200 meter elevation region, however, the 300+ meter thinning at the terminus has led to thinning upglacier and the location of the 1100 meter contour has shifted 1-1.5 kilometers upglacier. The snowline is evident in the 2003 Google Earth image. Landsat images from 1990 to 2013 indicate extensive retreat. The retreat from the 1990 terminus, red arrow, to the 2013 terminus, yellow arrow is 2.8 km, 120 m per year. The western feeder just above the terminus has narrowed at the pink arrow from 1 km wide in 1990 to 500 m wide in 2013. This suggests that retreat will soon lead to separation of Sawyer Glacier with the western arm and eastern arm both continuing a retreat. The 300 meter thinning in the last 50 years has left a sharp trimline beyond the current terminus marking the former ice height, that is well above the current fjord. The glacier is losing mass and retreating as is the nearby North Dawes Glacier.
The thinning combined with the rising snowline has resulted in a smaller accumulation zone. At the same time the retreat has reduced the calving rate as the terminus has narrowed and entered shallower water. The calving rate is related to water depth on these glaciers, Pelto (1991) . The reduced calving leads to a more positive mass balance, the increased snow line and reduce height of the glacier surface leads to reduced mass balance. This is equivalent to your bank account when you finish paying off your mortgage, but at the same time your income is declining. It will be interesting to observe the balance point of these two opposite forces. The University of Alaska Fairbanks began periodic altimeter surveys of the glaciers in the Sawyer Glacier region in 2000 and have noted a sharp decrease in surface elevation from the terminus to 1000 meters for the 2000-2009 period (Larsen et al, 2009). 
Warren Glacier Retreat, British Columbia, Canada
Warren Glacier in Garibaldi Provincial Park, British Columbia, Canada terminus retreat has been observed for over a century. 
A period of extensive retreat from 1890-1964 was followed by a period of minor advance from 1973-1977, and then rapid retreat from 1977-2009. Johannes Koch has documented this retreat in the map below and with the historic images as well, the work has been published with less colorful graphics (Koch et al., 2009).
. When I first saw the glacier in 1986 it had just retreated from the edge of the lake. By 2003 as seen in the somewhat blurry satellite image below, the glacier was 310 meters from the lake edge. In the 2009 Google Earth image the glacier is 500 meters from the lake edge. The rate of retreat over the 25 year period is 20 meters per year. The rate of retreat has again increased from 2003-2009, being 32 meters/year. 
The upper section of the glacier has unlike nearby Helm Glacier maintained some snow covered areas even in poor snow summers such as 2005 and 2009. This suggests the glacier can survive current climate with further retreat. The average thinning of Warren Glacier is similar to that of Helm, Sphinx and Sentinel Glacier at nearly 50 meters since 1928, note Figure 14 (Koch et al. 2009). This thinning due to ongoing negative mass balance has led to a 50% reduction in area since 1928. The large area loss as a percentage reflects the large relatively flat low lying basin now occupied by the lake. 
Presena Glacier Italy, Needs a Blanket
The Presena Ski Resort in Italy utilizes the Presena Glacier for its upper lifts and to extend its season. The warm summer of 2012 has been hard on this glacier. 
In 2008 this resort followed the example of Stubai, Austria and Les Arcs, France in utilizing an insulating blanket to reduce melting. Presena Glacier has lost a third of its volume since 1993. This led to adoption of wrapping the glacier in a 4 mm thick blanket of polypropylene matieral that in a test at the area reduced melt by 60%. The insulated blanket is apparent particularly along the lift in the image below. In 2012 the areas that were not protected by the blanket or groomed preferentially are evident as bare glacier ice. 
The insulating blanket is supposed to cover 90,000 square meters. The plan is to leave the blanket in place through the summer until mid-September. The entire glacier lost its snowcover in 2003 and 2005. The lower section of the glacier has separated into several thin sections that are rapidly melting away. In the photograph below the three separate terminus areas that are nearly completely detached from the upper glacier are noted with a T. The Lift (L) goes up the center of the upper glacier this area has lost its snowpack frequently as well by summer’s end in recent years. The Presena Glacier is responding to the warming climate in the same way as other Italian glaciers Forni Glacier and Dosde Glacier, and as the Italian Glacier Committee has noted observing that of glaciers observed in Italy in 2009 95 of the 111 glacier observed are retreating, 11 stationary and two advancing. The mass balance of Italian Glaciers in 2010 was again negative due to the high summer temperatures.
From a Glaciers Perspective 
