Tag: Featured

Bernal Glacier, Retreating from Chilean Fjord

On By mspeltoIn chile glacier retreat

Bernal Glacier terminus looking towards Estero las Montañas from Eñaut Izagirre and Camilo Rada.

Bernal Glacier drains east from the Sarmiento de Gamboa Range in Southern Patagonia terminating a short distance from the Estero las Montañas. The glacier is in the Alacalufes National Reserve and can be seen from boats traveling up the fjord. Davies and Glasser, (2012) indicate extensive recession of almost all glaciers in the range from 1870-2011. The fastest recession rate of recession of Bernal Glacier is from 2001-2011.  Melkonian et al (2013) observed that the Cordillera Darwin Icefield (to the south) had an average thinning rate of −1.5 m w.e/year from 2001-2011, while Willis et a (2012) quantify a rapid volume loss of the Southern Patagonia Icefield (SPI-to the north) from 2000-2012.  Incognita Patagonia has been exploring and mapping glaciers in the region since 2015 including a visit to Bernal Glacier in March 2017 that inspired this post Izagirre (2017). 

In 1986 there is no proglacial lake evident at the terminus of the glacier, red arrow.  By 2013 the glacier has thinned and retreated enough to reveal a pair of proglacial lakes separated by a moraine where the glacier terminated in 1986, red arrow.  By 2017 the proglacial lake has further expanded and glacier thinning has revealed larger areas of bedrock at the purple arrows.  There is not significant calving in the shallow proglacial lake and the retreat is driven by surface melting. The revegetation of the proglacial outwash areas in 2017 is also apparent. The amount of retreat from 1986 to 2017 is best viewed in the Google Earth image below.  The vegetation trimline from the 1980’s is evident.  Total retreat from 1986 to 2017 is meters. It is The glacier drains the same ice field as the retreating Dama Blanca Glacier and Balmaceda Glacier.

Landsat comparison of Bernal Glacier in 1986, 2013 and 2017 with the red arrow indicating the 1986 terminus.  Purple arrows indicate two areas of bedrock that will be exposed.

Bernal Glacier in Google Earth image from 2015. Red arrow is the 1986 terminus, note the vegetation trimline at that point.

Looking at the Bernal Glacier  from the base camp Eñaut Izagirre and Camilo Rada.

 

Dama Blanca Glacier Retreat, Southern Chile

On By mspeltoIn chile glacier melt, chile glacier retreat, climate change glacier retreat

Dama Blanca Glacier in Landsat images from 1986 and 2017.  Red arrow is the 1986 terminus, yellow arrow the 2017 terminus, purple dots the snowline and purple arrows a bedrock ridge.

Dama Blanca Glacier drains west from Chile’s Sarmiento de Gamboa Range in Southern Patagonia. terminating in Lago Verde in the Alacalufes National Reserve. Alacalufes NR features kelp rich fjords, Northofagus coastal forests and glacier clad alpine zones. Davies and Glasser, (2012) indicated extensive recession of almost all glaciers in the range from 1870-2011. They indicate the fastest recession rate of  Dama Blanca is from 1986-2001. This range is between the Southern Patagonia Icefield to the north and the Cordillera Darwin Icefield to the south. Incognita Patagonia has been exploring and mapping glaciers in the region since 2015, and have provided a map shown below in coordination with Camilo Rada and Natalia Martinez of the UNCHARTED project . On Marinelli Glacier, in the Cordillera Darwin Icefield, Koppes et al (2009) indicated a retreat of 13 km from 1960 to 2005. More recently Marinellli Glacieri retreated ~3.75 km from 1998 to 2014. Melkonian et al (2013) observed that the Cordillera Darwin Icefield had an average thinning rate of −1.5 m w.e/year with more rapid losses north and west. This is a continuation of the trend noted by Holmund and Fuenzelida (1995) that glaciers on the northern side have a trend of receding fronts. On the southern side the present extent of some glaciers are similar to their 20th century maximum extents. The region is characterized by strong climatic gradients, with high rates of precipitation on the southwestern side of the range where glaciers are faring better and drier conditions on the northern side. Given that the Sarmiento de Gamboa Range is north of Cordillera Darwin it would be expected this area would have substantial recession.

Here we compare satellite images from 1986-2017 to determine the changes of Dama Blanca Glacier. In 1986, the glacier terminated at the end of a peninsula on the south side of Lago Verde, red arrow. The snowline was at 500m. In 2013 the terminus has retreated significantly from the peninsula and the snowline is at 650 m. By 2017 the terminus has retreated 700 m since 1986. The snowline is obscured by clouds in the Landsat image. In February 2017 the snowline is at 700 m. There is also expansion of a bedrock rib on the west side of the glacier that extends to 800 m, purple arrow. The glacier remains actively crevassed to the glacier front as illustrated by the Google Earth image. The glacier will continue to retreat as long as calving continues; however, there is an increase in slope 200-300 m from the current glacier front suggesting the limit for lake development. Izagirre (2017) and the UNCHARTED project explored a number of glaciers in the Sarmiento de Gamboa Range this spring, that will lead to a detailed current map. The retreat here is similar to that of Balmaceda Glacier.

Dama Blanca Glacier in Landsat imags from 2013 and Sentinel image from Dec. 2016  Red arrow is the 1986 terminus, yellow arrow the 2017 terminus, purple dots the snowline and purple arrows a bedrock ridge.

Map from the UNCHARTED Project indicating glaciers of the Sarmiento de Gamboa Range and exploration routes.

Google Earth image of Dama Blanca Glacier in 2013, with the 1986 terminus position at the red arrow.

Vallunaraju Glacier Retreat, Peru 1992-2016

On By mspeltoIn peru glacier retreat1 Comment

Vallunaraju Glacier comparison in Landsat images from 1992, 1995 and 2016.  Red dots represent the 1992 margin and yellow dots the 2016 margin

The Cordillera Blanca, Peru has 27 peaks over 6,000m, over 600 glaciers and is the highest tropical mountain range in the world. Glaciers are a key water resource from May-September in the region (Carey, 2010).  Mark Carey describes the importance of glacier runoff to the Andean society in this region in his book”In the Shadow of Melting Glaciers: Climate Change and Andean Society“.  The loss of snow and consequent impacts is also beautifull illustrated by Ben Orlove and others in the book “Darkening Peaks : Glacier Retreat Sciecne and Society”. The glaciers in this range have been retreating extensively from 1970-2003, GLIMS identified a 22% reduction in glacier volume in the Cordillera Blanca. Vuille (2008) noted that the mean retreat rate has increased from 7-9 meters per year in the 1970’s to 20 meters per year since 1990. One of the glaciers that is receding  is Vallunaraju Glacier descending the west slopes of Vallunaraju. This glacier drains into the Rio Santa in Huarez, Peru. Baraer et al  (2012) notes the importance of glaciers to the Cordillera Blanca watersheds in the Huarez region, which receive at least 30% of their runoff from glaciers.  Rio Santa is undergoing a decline in dry-season flow that likely began in the 1970s and given the weak correlation between discharge and precipitation suggests the trend is driven by the glacier retreat. Bury et al (2013) examined glacier recession in the Cordillera Blanca, declining Santa River discharge, and alpine wetland contraction noting that water shortages already exist in the basin. Fraser (2012) reporting on recent NSF research project examining water from interdisciplinary perspectives throughout Peru’s Santa River watershed—from Cordillera Blanca glaciers to the Pacific Ocean.  That included Mark Carey, University of Oregon, Bryan Mark at Ohio State University, Jeffrey Bury at UC Santa Cruz,  Kenneth Young at the University Texas, Austin, and  Jeff McKenzie at McGill University.

In 1992 Vallunaraju Glacier extended to the cliffs immediately above the northern of two alpine lake adjacent to the glacier and within 400 m of the southern alpine lake, red dots in Landsat above.  By 2003 the glacier seen in Google Earth imagery had retreated from cliff top above the northern lake.  By 2011 the glacier had retreated 100-200 meters across the entire glacier front since 2003.  An area of bedrock between two terminus lobes had also begun to expand rapidly. This expansion continued up to 2016.  The retreat of the glacier from 2003-2016 averaged 180 m across the glacier front.  Retreat from 1992-2016 ranged from 200-300 m.  The glacier remains heavily crevassed indicating significant glacier flow resulting from substantial annual accumulation.  In every Landsat image analyzed there is a significant snowcovered area. The glacier though receding maintains a significant accumulation zone and can survive current climate.  The glacier is adjacent to the retreating Llaca Glacier.

2003 Google Earth image of Vallunaraju Glacier. Green line is the 2003 margin and red line the 2013 margin.
2011 Google Earth image of Vallunaraju Glacier. Green line is the 2003 margin and red line the 2013 margin.
2013 Google Earth image of Vallunaraju Glacier. Green line is the 2003 margin and red line the 2013 margin.
2016 Google Earth image of Vallunaraju Glacier. Green line is the 2003 margin and red line the 2013 margin. and orange line is the 2016 margin

Depot & Mondor Glacier Retreat, Antarctic Peninsula

On By mspeltoIn Antarctic Glacier retreat

Mondor and  (M) and Depot Glacier (D) at the tip of the Antarctic Peninsula in Landsat imagers from 1988, 2000 and 2017.  Yellow arrows indicates the 2017 terminus location of each.  The purple arrow indicates a bedrock ridge that has been expanding.

On the Trinity Peninsula,which is the region at the tip of the Antarctic Peninsula, are Depot and Mondor that flow north and south from the same accumulation zone emptying into Hope Bay and Duse Bay respectively. The Argentine Research Station, Esparanza is on Hope Bay. This region experienced some of the greatest warming on Earth from 1950-1990’s, but no additional warming since the 1990’s (Turner et al, 2016). This climate change has led to a rapid glaciological response, with 87% of glaciers around the Antarctic Peninsula now receding Davies et al (2012) . The most dramatic response has been the collapse of several ice shelves, Jones, Prince Gustav, Wordie, Larsen A and Larsen B. The Prince Gustav Ice Shelf connecting James Ross Island to the Trinity Peninsula collapsed after 1995 (Glasser et al 2011). There is limited surface melting on Antarctic glaciers, as a result almost all of the mass loss is from bottom melting under ice shelves and calving. These processes have led to and continue to drive dramatic retreat, thinning and acceleration of glaciers that feed ice shelves and the ice shelves, such as Rohss Bay and Coley Glacier Here we examine a glacier that is grounded, which limits the impact of enhanced melting from warmer ocean temperatures. Esparanza Base has a long term climate record with only December and January having a mean temperature above 0 C, at 0.4 and 0.5 C respectively. The record high temperature in Antarctica was recorded at Esparanza Base on March 24, 2015 at 17.5 C (Skansi et al, 2017). Specific anomalously warm days are when most mass balance losses occur. Barrand et al (2013) note a strong positive and significant trend in melt conditions in the region, driving the retreat.

In 1988 Depot Glacier terminus was north of a tributary entering on the west side of Depot Glacier. By 2000 the glacier terminus has receded and is adjacent to the northern side of this tributary.  By 2017 the terminus has retreated further and is nearly at the southern edge of the tributary glacier, a retreat of 500 m. Mondor Glacier in 1988 terminates south of bedrock ridge on the east margin of the glacier, yellow arrow. In 2000 the bedrock ridge has expanded and is closer to the terminus. By 2017 the bedrock rib has further extended north, purple arrow, indicating glacier thinning. The overall retreat of the terminus is 400 m from 1988 to 2017. The retreat rate increased after 2000, which is what Davies et al (2012) reported for the region. The rate of retreat is limited as the grounded glaciers have limited calving, and there is limited surface melt. The melt zone is not significant in any of the images on Mondor Glacier. On Depot Glacier there is a melt zone  below 200 m evident in both Goggle Earth images, purple arrows and the 2017 Landsat image. The limited changes of this glacier underscores that it is ocean warming that has been the key to date in glacier retreat in the region.  There has been a significant temperature rise, but it remains too cold for substantial surface melt.

Google Earth image from 2013 of Mondor Glacier terminus, black dots bottom and Depot Glacier black dots top.  Purple arrow indicates area of melting where snowpack has been lost. Yellow arrow a bedrock ridge on east side of Mondor Glacier.

Google Earth image from 2015 of Mondor Glacier terminus, black dots bottom and Depot Glacier black dots top.  Purple arrow indicates area of melting where snowpack has been lost. Yellow arrow a bedrock ridge on east side of Mondor Glacier.

 

 

 

Hallo Glacier Retreat, Katmai Alaska

On By mspeltoIn alaska glacier retreat

Landsat images of Hallo Glacier in 1985 and 2015 indicating the 1985 terminus position red arrows and yellow dots indicate 2015/2016 terminus location.  Purple dots show the snowline

Hallo Glacier is one of the larger glaciers in Katmai National Park draining east from Mount Steller and ending in an expanding proglacial lake east of Hallo Bay.  Hallo Bay is well known as a good location for brown bear watching (NPS).  Arendt and Larsen (2012) assess the glacier changes in Alaska National Parks they provide a map of the change in glacier extent from 1956-2009, Figure 7.  This indicates a significant retreat but it is not quantified. They further note a 15% decrease in areal extent of Katmai Region glaciers from 1956-2009.  Giffen et al (2015) indicate the glacier retreated 900 m from 1951-1987 and then advanced 150 by 2000. Here we utilize Landsat imagery to examine retreat from 1985 to July 2016 to examine the glaciers response.

In 1985 the glacier terminated just off the western shore of a small island in the lake.  The terminus front in the lake measured 3000 m in length.  The snowline averaged 1050 m across the glacier. By 1995 little retreat had occurred, the snowline was averaged 1050 m. In 2000 the glacier terminus had changed little from 1985.  The average snowline was at 1100 m. In 2015 the terminus had retreated 600 m from the island and 800 m along the northern shore of the lake.  The snowline is at 2000 m.  In 2016 the snowline is averages 1150 m , the highest observed. The terminus front in the lake remains 3000 m long.  The rate of retreat increased after 2000, and the glacier is poised for additional retreat. A 2013 Google Earth image illustrates that the lower 3.5 km of the glacier has a low slope and limited crevassing, except for minor crevassing along southern calving front.  This indicates the lake is likely to expand at least to this point.  Further that the glacier is poised for continued significant retreat and lake expansion.  The retreat is less than, but similar to that of nearby  FourPeaked  and  Spotted Glacier.

 

1995 Landsat image of Hallo Glacier indicating the 1985 terminus position red arrows.  Purple dots show the snowline

2000 Landsat image of Hallo Glacier indicating the 1985 terminus position red arrows and yellow dots indicate 2015/2016 terminus location.  Purple dots show the snowline

2016 Landsat image of Hallo Glacier indicating the 1985 terminus position red arrows.  Purple dots show the snowline.

2013 Google Earth image of Hallo Glacier, note low uncrevassed terminus tongue in lower 3.5 km.

 

Bridge Glacier Terminus Collapse, BC, 4 km retreat 1985-2016

On By mspeltoIn Canada glacier retreat1 Comment

Bridge Glacier comparison in 1985 and 2016 Landsat Images.  Red arrow is the 1985 terminus, yellow arrow the 2016 terminus and purple arrows indicate locations where tributaries have separated between the two dates. 

Bridge Glacier is an 17 km long outlet glacier of the Lillooet Icefield in British Columbia. The glacier ends in a rapidly expanding glacial lake and had an observed retreat rate of 30 m per year from 1981-2005 by Allen and Smith (2007). They examined the dendrolchronology of Holocene advances of the glacier and found up to 2005 a 3.3 kilometer advance from the primary terminal moraine band, with the most extensive advances being early in the Little Ice Age.  Chernos (2016)  indicates that the glacier in 2013 is approaching the upglacier end of the lake, which will lead to reduced retreat rates.  Here we compare Landsat imagery from 1985 to 2016 to determine response.

In 1985 the proglacial lake was 2.5 km long and 3.5 km upglacier of the terminus a major tributary joins.  The transient snow line is 2100 m. By 1993 the glacier has retreated 200-300 m and the snowline was at 2150 m.  By 2004 the terminus in a Google Earth image the terminus had retreated 1100 m since 1985.  By 2004 the tributary from the north has separated from the north side of the glacier.There are also some evident areas where the proglacial lake is visible up to 800 m upglacier of the terminus.  This suggests imminent collapse of this section of the terminus, which is afloat.  Matt Chernos researching this glacier documents this well with images.  Chernos (2016) observed that calving due to greater water depth and terminus buoyancy was key to retreat, but that most volume loss stemmed from melting.   In 2016 the terminus has retreated beyond the former junction of the Bridge Glacier and the northern tributary.  The glacier terminus is now within 500 m of a slope increase, likely marking the end of the developing lake basin. The total retreat in 31 years has been 4.1 km, this is a rate of 130 m/year, much faster than before. The 3 km retreat from 2004 to 2016 indicates a retreat of 250 m/year.  The separation of the three tributaries, purple arrows are not impacted by calving and indicate melting alone is sufficient to drive significant retreat.  The enhanced melt is also the cause of the high snowlines,, in 2016 the snowline is at 2150 m. The retreat is faster than nearby Klippi and Jacobsen Glacier, but both of those are also retreating fast.

This continued retreat and area loss will lead to glacier runoff decline in summer. This is crucial to the large Bridge River Hydro complex. This complex managed by BC Hydro can produce 490 MW of power, which is 6-8% of Province demand. Stahl et al (2008) note in their modeling study of the glacier that ,”The model results revealed that Bridge Glacier is significantly out of equilibrium with the current climate, and even when a continuation of current climate is assumed, the glacier decreases in area by 20% over the next 50 to100 years. This retreat is accompanied by a similar decreasein summer streamflow.”   Lillooet News (2016) notes that BC Hydro has commissioned research on the glacier to investigate impact on runoff tiiming. This parallels our findings on the Skykomish River in the North Cascades, Washington Pelto (2011).  The change in timing and the hydropower also impact salmon with late summer runs of chinook and fall coho runs.

Bridge Glacier comparison in 1993 Landsat Image.  Red arrow is the 1985 terminus, yellow arrow the 2016 terminus.

2005 Google Earth image of Bridge Glacier, note tributary separation from the north.

Closeup of terminus indicating exposures of proglacial lake upglacier of the terminus.Bridge Glacier Retreat Acceleration, BC, Canada

Klippi Glacier Retreat Causes Separation, British Columbia

On By mspeltoIn Canada glacier retreat1 Comment

Klippi Glacier in Landsat images of 1987 to 2016. Red arrows indicate 1987 terminus, yellow arrows 2016 terminus and purple dots the transient snowline. 

The glacier beings at 2600 m sharing a divide with Klinaklini Glacier, flowing northwest from Silverthrone Mountain and terminating at  1040 m in 1987. Klippi Glacier drains into the Machmell River, Owikeno Lake and then River Inlet on the British Columbia Coast. The Machmell River is an important spawning area in its lowest 20 km, particularly for sockeye salmon, with chinook, coho, pink and chum salmon also present  The Machmell River is accessible to anadromous fish to the cascades just downstream of junction with Pashleth Creek, where runoff from the Pashleth Glacier enters (Hillaby, 1998).  The Rivers Inlet sockeye stock is the second largest in BC and has recently received much attention because of a dramatic decline in total abundance from the 1980s.  In the 1980’s Machmell River escapement numbers averaged 20,000, dropping to 5000 in the 1990’s  (Rutherford et al 1998).  This has led to an ecosystem study by UBC and SFU  of Rivers Inlet. Rivers Inlet in the 1970’s began to experience sockeye population  decline. Harvest rates were reduced in the 1980’s and the commercial fishery closed in 1996.  In 1999 the  stock reached a record low of ~ 3600 fish, just 0.1% of historic levels (Rivers Inlet Ecosystem Study). The commercial fishery has remained closed since 1996, with  a small amount of fishing permitted by the Wuikinuxv First Nation for cultural purposes, the stock has not recovered.

Here we examine the response of this glacier to climate change from 1987-2016 using Landsat imagery. In 1987 Klippi Glacier’s two main tributaries joined 1.8 km from the terminus, red arrow in each image.  The transient snow line was at 1800 m, purple dots.   By 1995 the glacier had retreated 750 m but still had a joined terminus. The transient snowline remained close to 1850 m.  In a 2012 Google Earth image the tributaries are still connected, but barely as a drainage stream has nearly isolated them.  The lower 800 m of both glaciers illustrate limited crevassing and significant downwasting. By 2016 the tributaries had separated with a retreat of  1400 m since 1987.  The transient snowline in 2016 was at 1900-1950 m. The glaciers will continue to retreat due to high snowlines in recent years with each of the last three years being above 1950 m by the end of the melt season.  The retreat here is similar to that of other valley glaciers in the region Jacobsen Glacier and Bridge Glacier.

Map of the Klippi Glacier region reflecting the 1980’s terminus position of the glacier. Red arrows indicate 1987 terminus, yellow arrows 2016 terminus

Klippi Glacier in Landsat image from 1995. Red arrows indicate 1987 terminus, yellow arrows 2016 terminus and purple dots the transient snowline. 

2012 Google Earth image of the terminus area of Klippi Glacier. Yellow arrow indicate 2016 terminus location. 

Cavagnoli Glacier, Switzerland Fading Away

On By mspeltoIn switzerland glacier retreat

Google Earth image of Cavagnoli in 2010 and a Sentinel 2 image from Sept. 9  2016.  Ice masses are numbered.  No retained 2016 snowpack, note the lighter colored snow on the upper Basodino Glacier

Cavagnoli Glacier (Ghiacciaio dei Cavagnöö) drains south into Lago dei Cavagnoli (Lago dei Cavagnöö), which is impounded by a dam that is 111 meters high.  The glacier like its neighbor Basodino Glacier  is in the Ticino River watershed and supplies the Robiei/Cavagnoli Hydropower system. The Cavagnoli Hydropower plant can provide 28 MW of power. The Swiss Glacier Monitoring Network noted that glacier area in 1973 was 1.36 square kilometers, when the glacier was a single ice mass.. The Swiss Glacier Monitoring Network has observed the annual retreat of this glacier since 1980, total retreat up through 2013 is 378 m of the main glacier.  The top of the glacier has also been retreating this is a symptom of a glacier that will not survive (Pelto, 2010). Huss and Fischer (2016) indicate that the majority of the small alpine glaciers, less than 0.5 square kilometers will disappear in the next 25 years.

This glacier has no accumulation zone in 2003, 2005, 2007 or 2010 Landsat and Google Earth imagery. The glacier itself by 2010 had separated into five separate ice masses that are each melting quickly away.  The glacier as viewed from below and from directly above in Google Earth Imagery indicates a thin glacier with few crevasses.This has become a reoccurring pattern for this glacier, and also is a sign of a glacier that cannot survive.   In 2010 Google Earth imagery the largest ice mass was 0.4 square kilometers and none of the ice masses appear destined to survive. In 2016 the Sentinel 2 image indicates there are four remaining ice masses, with a combined area of 0.3 square kilometers, with the largest ice mas now at less than 0.2 square kilometers.  There is no retained snowpack in the 2016 Sentinel image either. On the main ice mass there is a meltwater stream from the top to the bottom of the glacier indicating that even the top of the glacier is usually snow free by summer’s end. This glacier is a small relic of its former mapped extent.   The glacier will not persist, but is also an example that even small glaciers in poor health do not disappear quickly.

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Basodino Glacier, Switzerland Mass Balance Loss & Hydropower

On By mspeltoIn switzerland glacier retreat

Basodino Glacier in August and September of 2016 illustrating the upward shift of the snowline in the 15 days between the Landsat (left) and Sentinel (right) image. purple dots mark snowline. 

Basodino Glacier is a small northeast facing slope glacier in the southern Swiss Alps.  The glacier is in the Ticino River watershed and supplies the Robiei Hydropower system. The glacier is in the same basin as Cavagnoli Glacier, which is fading away. The main branch presently covers an area of 1.8 km2 and extends from 2562 to 3186 m.  In 1973 the glacier had an area of 2.3 km2 .  Detailed mass balance investigations have been carried out since 1990.  During this period the glacier has lost more than 11 m w.e. thickness.  In seven years from 1980-2014 the glacier has had an AAR below 10 (Bauder, 2016).  This is indicative of minimal retained accumulation and not a consistent accumulation zone (Pelto, 2010) .  Huss (2012) noted that mean glacier mass balance in the European Alps was −0.31  m w.e./ year from 1900–2011, and −1 m w.e. /year over the last decade.  For Basodino Glacier the loss during this enite period averaged ~-0.2 m w.e./year (Huss, 2012).  The glacier advanced 95 m from 1967-1986 and has retreated 260 m since, front observations are completed and submitted by Claudio Vallegia of Ticino, Sezione Forestale (Swiss-ETHZ, 2016).

Water from glacier melt  is channelled to the Robiei-Zött reservoirs and hydro plants, generating enough electricity for a city. The Cavagnoli and Naret reservoirs at 2310 m feed the Robiei power station, situated 400 m below. The Robiei power station is also capable of pumping the water from the Robiei-Zött up to the higher Cavagnoli-Naret reservoirs.

Basodino Glacier in late August of 2016 had 5-60% of the glacier still in the accumulation zone. two weeks later on Sept. 9, 2016 the glacier had 35% of the glacier in the accumulation zone.  This is the accumulation area ratio, which needs to be above 55% for equilibrium.  For Basodino Galcier 2016 will be another year of mass balance loss and retreat.  The detailed monitoring will provide specific values for each reporting to the Swiss Glacier Monitoring Network system and the WGMS.

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Trinity-Wykeham Glacier Retreat, Causing Separation, Ellesmere Is. Canada

On By mspeltoIn Canada glacier retreat

Trinity (T) and Wykeham (W) Glacier in 1999 and 2016 Landsat images.  Red arrow indicates 1999 margin, yellow arrow 2016 margin, yellow dots the actual ice front. 

Trinity (T) and Wykeham (W) Glacier flow east from Ellesmere Island into a fjord off of Nares Strait.  Until recently the two have been joined just before the terminus. Millan et al (2017) observed glaciers in the region.  They noted a change  in ice loss from Queen Elizabeth Islands glaciers, during the 1991–2005 mass loss was 52% from ice discharge and 48% from surface mass balance. During 2005–2014, the mass loss increased dramatically with 10% from ice discharge and 90% from surface balance losses. They reported that Trinity and Wykeham Glacier had a stable velocity from 1991-2009 and doubled in speed by 2015.  They noted a retreat of 1.8 km for Wyjkeham Glacier form 1991-2015 and 5 km for Trinity Glacier.  Here we examine Landsat imagery from 1999, 2002, 2004 and 2016 to identify changes in the two glaciers.

In 1999 the two glaciers are joined with a 14 km long ice front.  The ice front of Trinity to the North extends to an outlet glacier entering the fjord from the north.  The southern margin of the joint front extends 4 km beyond a mountain marking the southern entrance to what will be Wykeham Fjord (SW).  In 2002 there is little change in the icefront.  By 2004 Trinity Glacier has retreated 4 km along the northern edge and 5 km on the southern edge, now terminating at the eastern end of a ridge marked (MR).  Wykeham Glacier has experienced a minor retreat.  From 2004 to 2016 there is little change in the front of Trinity Glacier, while Wykeham Glacier has retreated  1.5 km along the southern margin.  This illustrates the substantial ice discharge loss before 2004 of the two glaciers and limited ice discharge net loss after 2004, as Millan et al (2017) noted. The strong surface mass balance losses of recent years has led to thinning, which should drive further retreat. The two glacier will enter their own developing fjords. In 2016 it is evident that the melt area extends quite high on the glacier, bottom image.  Melt ponds extend up to at least 800 m, purple arrows.  The acceleration in 2015 if it continues will deliver a much higher flux further reducing volume and driving retreat.  We have seen this pattern of  thinning, acceleration and retreat on many glaciers typically driven by greater surface melt and frontal/basal melt, depending on flotation. The retreat here is similar to that of Mittie Glacier also on Ellesmere Island.

Trinity (T) and Wykeham (W) Glacier in 2002 Landsat image.  Red arrow indicates 1999 margin, yellow arrow 2016 margin, yellow dots the actual ice front. 

Trinity (T) and Wykeham (W) Glacier in 2004 Landsat image.  Red arrow indicates 1999 margin, yellow arrow 2016 margin, yellow dots the actual ice front. 

Trinity (T) and Wykeham (W) Glacier in 2016 Landsat image.  Red arrow indicates 1999 margin, yellow arrow 2016 margin, yellow dots the actual ice front and purple arrows melt ponds. 

A River Runs 40 km Across the Greenland Ice Sheet

On By mspeltoIn glacier climate change, Glacier Observations, Greenland glacier retreat

Supraglacial stream, on July 26, 2016 Landsat image, stretching 40 km across the ice sheet from the transient snowline, which marks the boundary between the percolation zone and the wet snow zone,  west toward the ice sheet margin, note black arrows.  

The Greenland Ice Sheet has experienced a significant increase in surface melt.  This is due both to warmer temperatures and enhanced melt due to a reduction in reflectivity-albedo. The expansion in melt area, duration and intensity (NSIDC, 2015)  has also generated large volume of meltwater transported via supraglacial streams.  Recent work by Tedesco et al (2016) and Kintisch et al (2017) illustrate three key reasons for the albedo change in the melt zone.

1) Upon melting and refreezing, ice crystals lose their branched shape, grow larger and rounder, which reduces the reflectivity of the snow by as much as 10%.

2) Satellite data show that the margins of the ice sheet have darkened by as much as 5% per decade since 2001. Dust trapped over the centuries has become concentrated at the melting edge of the ice sheet.

3)   The combination of algae and bacteria with dust generates a sludge—known as cryoconite. This dark material gathers in depressions decreasing albedo. Black and Bloom is a project focused on how dark particles (black) and microbial processes (bloom) darken and accelerate the melting of the Greenland Ice Sheet

Tedesco et al (2016) noted the negative trend in albedo is confined to the regions of the ice sheet that experience summer melting. They also observed no trend during the 1981–1996 period. Their analysis indicates the albedo decrease is due to the combined effects of increased air temperatures, which enhances melt promoting growth in snow grain size and the expansion of bare ice areas, and to increasing concentration of dark impurities on ice surfaces. Kintisch et al (2017) noted the same mechanisms with warmer summers also enhancing microbes and algae growth on the wetter surface of the ice, producing more cryocontie, that reduces albedo absorbing more solar energy. Cryoconite is more spatially limited than the other mechanisms. They also observed that soot and dust that blow in from lower latitudes and darken the ice are also increasing.

The darker surface enhances melt which generates more meltwater largely drained in the melt zone by supraglacial streams. Smith et al (2015) documented the surface drainage in the ablation zone of the southwest GIS. They focused on documenting the distribution of over 500 high order stream channel networks in a 6812 square kilometer region, inland from Kangerlussuaq.  All of the stream networks terminated in moulins before the ice sheet edge (NASA, 2015).  This indicates that moulins are common, important and sparse.

Poinar et al (2015) observe the longest streams in the 30-50 km range. Here we examine two streams one in detail using Google Earth that is 30 km long and a 40 km long surface stream in 2016 observed in Sentinel 2 and Landsat images. That the surface rivers can travel this distance across the surface before draining via a moulin indicates that the glacier is not structurally like Swiss cheese (Pelto, 2015).  The Google Earth detailed view illustrates both the darker surface, the maturity and hydrologic efficiency of the thermally incised meltwater streams.

The stream observed in Google Earth in its mid-reach has an average of 15 m in width.  The slope of the ice sheet is 1/120 in this region, with the river beginning at 1320 m and ending at 1070 m.  Gleason et al (2016) examined numerous supraglacial streams and noted that supraglacial streams with a width of 15-20 m and slopes of 1/100 to 1/200 had a depth of 1.5-2.0 m and velocity of ~0.5 m/sec.  This suggests the stream here has a discharge  of 7-10 cubic meters per second. The darkness of the ice surface indicating a low albedo is also apparent.  The ice is not nearly as dark when standing directly on it as it is in the macro-scale.

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The second stream is seen in a Sentinel  image from July 15 and a Landsat image from July 26. The black arrow indicate the stream that is 40 km long.  The stream extends from 110 km from the edge of the ice sheet to within 75 km. The stream begins near the transient snowline at 1650 m and ends near 1400 m, creating a slushy valley above the local percolation zone. The stream in early July flows through the wet snow zone. By the end of the July the lower section of the stream becomes a bare ice region, the upper remains in the  wet snow zone.

Supraglacial stream in mid-July Sentinel images stretching 40 km across the ice sheet from the transient snowline west toward the ice sheet margin. 

 

 

Shoup Glacier, Alaska Retreat, Thinning, Velocity Decline

On By mspeltoIn alaska glacier retreat, climate change glacier retreat

Shoup Glacier comparison in 1986 and 2016 Landsat images.  The glacier retreated 1900 m in this interval.  Red arrow is 1986 terminus, yellow arrow the 2016 terminus, green arrow rock rib emerging from beneath glacier, purple dots a landslide deposit, and purple arrow the snowline.

Shoup Glacier is between the Columbia Glacier and Valdez draining from the Chugach Mountains in southern Alaska.  The glacier was a tidewater terminating glacier until 1953 (McNabb et al, 2014).  From 1985 to 2011 McNabb et al (2014) noted a 1.7 km retreat.  The retreat was enhanced by significant lacustrine calving in an expanding tidal lagoon.  Here we examine Landsat and Sentinel images from 1986-2016 to identify recent and potential future changes.

In 1986 the glacier extends to the red arrow in the midst of a tidal lagoo. The glacier is 2.5 km wide at the sharp bend in the glacier 2.5 to 3 km from the terminus, green arrow.  There is significant crevassing at this bend indicating an increase in slope.  There is an landslide/avalanche deposit near the junction with a tributary, purple dots.  By 2002 the glacier has retreated 1.5 km since 1986, the minor ice cliff at the terminus indicates the glacier ends in shallow water near the end of the tidal lagoon.  The glacier is now 2 km wide at the sharp bend.  The landslide deposit, purple dots,  has shifted little since 1986. The snowline is at 1200 m in 2002.  By 2016 the glacier has retreated an additional 400 m since 2002, 1900 m since 1986.  The glacier no longer terminates in the lagoon.  A bedrock rib at the sharp bend has been exposed and the glacier is only 500 m wide now and this bend is just 500 m from the terminus, green arrow.  A closeup of this rib in a 2016 Sentinel image indicates why the crevassing had occurred, it is also clear this is an extension of the ridge that runs east from the glacier.  This is a band of erosion resistant rock.  This suggests that a basin exists above the this bedrock rib/ridge and a new lake will form.  The glacier slope from the green arrow for the next 2 km upglacier is quite low 1/40, again indicative of a basin beneath the lower glacier.  There is an increase in crevassing 2 km above the current terminus,  suggesting another increase in surface slope and the probable limit of the basin.  In 2016 the snowline is at 1250 m.  The landslide deposit remains little changed since 2002, indicating a low velocity in this region.  Burgess et al (2013) indicates the velocity of the Shoup Glacier near the terminus is in the range of 100 m annually.  The tributary is clearly significantly less. The low velocity, thinning and retreat indicates the glacier is continuing to lose volume via surface melting, despite no longer calving as Larsen et al (2015) have indicated is the prime mechanism for ice loss.  The retreat of this glacier is similar to that of nearby Valdez Glacier.

Shoup Glacier comparison in 2002 Landsat image.  Red arrow is 1986 terminus, yellow arrow the 2016 terminus, green arrow rock rib emerging from beneath glacier, purple dots a landslide deposit, and purple arrow the snowline.

Shoup Glacier terminus in 2016 Sentinel 2 image.  Green arrows indicate rock rib.