Author: mspelto

Professor of Environmental Science at Nichols College in Massachusetts since 1989. Glaciologist directing the North Cascade Glacier Climate Project since 1984. This project monitors the mass balance and behavior of more glaciers than any other in North America

Glacier Nef, Patagonia, Chile retreat 1987-2016.

On By mspeltoIn chile glacier melt, chile glacier retreat, Chile glaciers and hydropower

nef compare

Comparison of 1987 and 2015 Landsat images of Nef Glacier at right and Cachet Glacier at left.  Indicating retreat of Nef Glacier from red arrows to yellow arrows of 1.8 km and development of a new lake at the terminus. Purple arrows indicate upglacier thinning leading to separation of glacier tributaries. 

Glacier retreat and thinning is particularly strong in the Patagonian icefields of South America. The two largest temperate ice bodies of the Southern Hemisphere are the Northern Patagonia Icefield 4,000 km2 and the Southern Patagonia Icefield, 13,000 km2. It has been estimated that the wastage of the two icefields from 1995–2000 has contributed to sea level rise by 0.105 ± 0.011 mm year,which is double the ice loss calculated for 1975-2000 (Rignot et al. 2003).   Davies and Glasser (2012) work, has an excellent figure indicating two periods of fastest recession since 1870, are 1975-1986 and 2001-2011 for NPI glaciers, which suggests that ice volume loss increased after 2000. They noted the loss was 0.07% from 1870-1986, 0.14% annually from 1986-2001 and 0.22% annually from 2001-2011. Glasser et al (2011) find the recent ice volume rate loss is an order of magnitude faster than at other time intervals since the Little Ice Age. Baker River (Rio Baker) is located to the east of the Northern Patagonia Icefield and is fed mainly by glacier melt water originating from the eastern outlet glaciers of the icefield Leones, Soler, Nef, Colonia. Rio Baker is the most important Chilean river in terms of runoff, with an annual mean discharge of about 1000 m3/s Lopez and Casassa (2009). Glacier Nef is one of the main glaciers feeding Rio Baker. Rio Baker was a proposed critical hydropower resource for Chile. Hidroaysen Project had proposed 5 dams on the Baker and Pascua River generating 2750 MW of power, all three proposed dams on the Rio Baker have been cancelled.

Glacier Nef began to retreat into a moraine dammed proglacial lake in 1945 (Loriaux and Casassa, 2014). By 1987 the lake remained less than 1 km long, with glacier thinning predominating over retreat. From 1987 to 2015 the glacier has retreated 1.8 km calving into the growing lake.  The lake width was essentially uniform during this phase of retreat There is not significant retreat from 2015 to 2016. The lake is currently about 5.4 square kilometers and has a mean depth of ~125 m (Loriaux and Casassa, 2014).  In 2015 Glacier Nef has not reached the head of this proglacial lake and will continue to retreat. The west side of the terminus is debris covered and has a fringing proglacial lake that has developed after 2000 and will aid in the continuing retreat. The terminus is currently at a pinning point, where the valley is constricted providing greater terminus stability. Further retreat will lead to an expansion of the embayment and calving front, leading to a further increase in glacier retreat. The lack of elevation change of the lower glacier and the isolated proglacial lake here suggests the lake will expand laterally as well as in length. The debris cover is slowing the thinning and retreat of the western margin. The purple arrows indicate thinning upglacier in a former tributary glacier. The 2016 Landsat image indicates a high snowline at 1350 m, purple dots.  Willis et al (2011) observed that the thinning rate of NPI glaciers below the equilibrium line has increased substantially from 2000-2012, partly an indication of a higher snowline indicative of greater ablation and a longer snow free period lower in the ablation zone. For example on Nef Glacier by January 8, 2016  the snowline was at 1300 m and remained high up until at least the mid-march image below. The retreat follows the pattern of enhanced calving in a proglacial lake for NPI glaciers such as Gualas Glacier, Reichert Glacier, Steffen Glacier, and Colonia Glacier.
nef 2016

2016 Landsat image of Nef Glacier indicating terminus yellow arrow and source of the debris for the debris covered terminus. 

nef terminus

Closeup of Nef Terminus from Chile Topographic Application.  Notice the widening valley just above terminus.  Debris cover is insulating ice on west side of terminus.  

Mittlerer Guslarferner, Austria Disintegrates 2003-2015

On By mspeltoIn Uncategorized

guslarferner compare

Google Earth images of Mittlerer Guslarferner (MG) and Grosser Guslarferner (GG) from 2003 and 2015.  The green line is the 2003 margin. 

Mittlerer Guslarferner and Grosser Guslarferner are a pair of Austrian glaciers in the Ötztal Alps. A comparison of Google Earth images from 2003 and 2015 indicates that substantial changes that have occurred in just 12 years. In this region between 1997 and 2006 Abermann et al (2009) noted an 8.2% area loss in just a decade for Ötztal Alps glaciers. The Austrian Alpine Club completes an annual terminus survey of glaciers. This survey is one of the world’s most comprehensive, and is currently directd by Andrea Fischer. The report on the 2015 inventory documents another poor year with 96% of the 92 glacier retreating.  The average retreat was 26 m, with Hornkees and Gepatschferner leading the way.  Abermann et al (2010) Figure 2 illustrate the beginning of the separation of MG in 2010. A comparison of the two glaciers indicates that frontal retreat has been 330 m for Mittlerer Guslarferner and 260 m for Grosser Guslarferner. The frontal changes do not tell the story for Mittlerer Guslarferner.  In 2003 the glacier did not have any retained snowcover and very limited firn retained from previous years, this indicates the lack of an accumulation zone, without which a glacier cannot survive (Pelto, 2010).  The glacier is continuous across a width of 1300 m and has an average length of 300 m. The glacier has disintegrated into four parts since 2003, with outcrops of rock emerging not just near the terminus, but near the top of the glacier, red arrows.  In 2015 with a few weeks left in the melt season only 10% of the glacier has retained firn. Glacier area has declined by 40% in just a decade.

m guslar 2003

Mittlerer Guslarferner in 2003

m guslar 2015

Mittlerer Guslarferner  in 2015, having separated into four segments with new outcrops near top of glacier.

North Fork Grand Plateau Glacier, Alaska-Spectacular 3 km Retreat 2013-15

On By mspeltoIn alaska glacier retreat, climate change glacier retreat, glacier climate change, Glacier Observations1 Comment

south alsek glacier compare

North Fork Grand Plateau Glacier comparison in 2013 and 2015 Landsat images.  Illustrating the rapid retreat and lake expansion in just two years. Pink arrow is 1984 terminus, red arrow is the 2013 terminus and yellow arrow 2015 terminus. The orange dots are the 2013 terminus. 

The Alsek Glacier is a large glacier draining into Alsek Lake and the Alsek River in southeast Alaska  Its neighbor the Grand Plateau Glacier has one fork  flows north and joins the Alsek Glacier terminating in Alsek Lake. The USGS topographic map compiled from a 1958 aerial image indicates a piedmont lobe spread out into a proglacial lake that is less than 3 km wide, with a combined ice front of the Alsek Glacier and North Fork Grand Plateau Glacier.. There is a 10.5 km wide calving front in the lake.  By 1984 the glacier had separated into a northern and southern calving front on either side of an island and had a 13 km wide calving front.   Here we focus on the southern lobe, which is comprised of a lobe of  the Alsek Glacier and a the North Fork Grand Plateau Glacier that merges with Alsek Glacier.  From 1984 and 1999 the two lobes separated as the North Fork retreated 2.2 km.  From 1999 to 2013 the North Fork retreated 1.5 km up a newly forming southern arm of Alsek Lake.  The retreat over the 30 period of 3.7 kilometers averaged ~120 meters/year. Landsat imagery in 2013 and 2014 indicate extensive calving from the North Fork Grand Plateau Glacier.  From 2013 to 2015 the terminus has retreated 3.0 km, 1.5 km/year.  This is likely the fastest retreat rate in recent years of any Alaskan glacier. The calving front in Alsek Lake has been reduced to 5.4 km in three separate sections.

The retreat has been similar in timing to nearby Alsek River watershed glaciers Walker Glacier, East Novatak Glacier and North Alsek Glacier..  The rapid retreat is enhanced by calving in proglacial lakes, a common issue increasing area loss of Alaskan glaciers.  Yakutat Glacier is an example of rapid lake expansion. In the case of Yakutat Glacier unlike the Alsek or Grand Plateau Glacier the glacier lacks any high elevation accumulation zone and cannot survive without an accumulation zone (Trüssel et al 2015).  Grand Plateau Glacier and Alsek Glacier both have large accumulation areas above 2000 m, that are well above the snowline at all times.  The Alsek River is a destination for sockeye salmon fishing and river rafting, see Chilkat Guides or Colorado River and Trail Expeditions.  Continued expansion of lake area as glaciers retreat in the watershed, is changing the nature of the Alsek River.

alsek map

USGS Topographic map of region from 1958 aerial images indicating merging of Alsek Glacier and North Fork Grand Plateau Glacier. 

alsek 1984

1984 Landsat image indicating terminus locations. Pink arrow is 1984 terminus, red arrow is the 2013 terminus and yellow arrow 2015 terminus.

alsek 1999

1999 Landsat image indicating terminus locations. Pink arrow is 1984 terminus, red arrow is the 2013 terminus and yellow arrow 2015 terminus.

alsek 2014

2014 Landsat image.  indicating terminus locations. Orange dots indicate the ice front. Pink arrow is 1984 terminus, red arrow is the 2013 terminus and yellow arrow 2015 terminus.

Krayniy Glacier Retreat, Novaya Zemlya

On By mspeltoIn glacier climate change, Glacier Observations, Novaya Zemlya glacier retreat

kraniy

Krayniy Glacier (Ky) comparison in 1990 and 2015 Landsat images.  Red arrow is 1990 terminus and yellow arrow is the 2015 terminus.  Purple arrows indicate upglacier thinning and green arrow a location of a glacier dammed lake.

Krayniy Glacier is an outlet glacier that drains the northern side of the Novaya Zemlya Ice Cap into the Barents Sea. This outlet glacier is just southwest of Tasija Glacier (T) and like that glacier has retreated over 1.2 km since 1988. Krayniy Glacier has been retreating like all tidewater glaciers in northern Novaya Zemlya (LEGOS, 2006). The terminus of the glacier has a pinning point on an island at present. Carr et al (2014) identified an average retreat rate of 52 meters/year for tidewater glaciers on Novaya Zemlya from 1992 to 2010 and 5 meters/year for land terminating glaciers. The increased retreat rate coincides with the depletion of ice cover in the Barents Sea region and a warming of the ocean. Both would lead to increased calving due to more frontal ablation and notch development similar to at Svalbard (Petlicki et al. 2015).  The spring of 2016 features an ice free west coast of Novaya Zemlya leading to enhanced calving front melting.

In 1990 the glacier had an east west terminus across the head of the fjord.  There was a substantial glacier dammed lake impounded by the glacier (green arrow), and there was a narrow connection with Tasija Glacier.  The glacier dammed lake persisted in Landsat images in 1999, 2000, 2003 and 2006.  In 2013 the proglacial lake had drained.  In 2014 and 2015 the lake has not reformed, an indication of glacier thinning at the outlet location. This thinning is evident at both purple arrows,where the connection with the Tasija Glacier has been severed and a substantial nunatak has emerged amidst the glacier. From 1990 to 2015 the glacier has retreated more on the eastern margin with 1250 of retreat opening up the embayment.  Retreat at the island in the glacier center has been 500 m since 1990. The western section of the glacier has retreated little. The eastern embayment will continue to drive retreat and glacier thinning that will reduce contact with the island pinning the eastern half of the glacier.  The thinning is evident at the purple arrows. The glacier will likely retreat from this island in a fashion similar to Tasija and Chernysheva, which will lead to increased rate of retreat of the entire ice front.

kraniy lake

1988, 2006 and 2014 Landsat images indicating the continued presence of glacier dammed lake from 1988-2006 and continued absence from 2014 and 2015.arctic.seaice4262016

Sea ice image from Cryosphere Today

Pacific Northwest Glaciers: Widespread early Melt Season Arrival

On By mspeltoIn alaska glacier retreat, Canada glacier retreat, glacier climate change, Glacier Observations

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The 2016 melt season is off to an early start in Greenland, but this is not the only location.  This winter proved to be warm, but relatively wet across much of the Pacific Northwest.  A look at the average freezing level (determined by North American Freezing Level Tracker-Developed by John Abatzoglou and Kelly Redmond) from January 1 to April 20 indicates freezing levels well above average on Mount Baker North Cascades, Washington, Bugaboo Mountains British Columbia and Juneau Icefield Alaska.  Reports from the field in British Columbia, Alaska and Washington identify a peak snowpack in late March instead of early May at glacier elevations.

In British Columbia the University of Northern British Columbia field team is currently on Conrad Glacier in the Bugaboos, having just finished Kokanee Glacier. This is part of a five-year study led by Dr. Brian Menounos, UNBC Canada research chair in glacier change, funded by the Columbia Basin Trust. UNBC PhD student Ben Pelto heads the research team. They have found that despite snowpack observations for the region from the BC River Forecast Centre of slightly above average snowpack on April 1, the high winter freezing levels and very warm April conditions have left the Kokanee Glacier snowpack quite similar to the low 2015 snowpack, with close to 4.5 m of retained snowpack.  The snowmelt season was noted by the River Forecast Centre as starting several weeks early. The freezing level from January-April 20 was a record for the 1948-2016 period by over 100 m for the Bugaboo mountains.  The region based on the warm spring causing rapid snow melt at lower elevations is leading many, Including John Pomeroy, to expect high forest fire danger and low streamflow during the summer across the Western Canada. 

zillmer snowpit

Snowpit being excavated on Zillmer Glacier April 2016, Jill Pelto and Micah May. (Ben Pelto)

BenPelto-and-JillPelto-BCGlacierClimateProject-Kokanee-April2016-TomHammond

Jill Pelto and Ben Pelto measuring density of firn core on Kokanee Glacier. (Tom Hammond)

In Alaska  USGS-Glaciology has been completing GPR surveys of their benchmark glaciers in recent weeks.  On the Juneau Icefield Lemon Creek Glacier is a reference for the World Glacier Monitoring Service.  Mass balance records exist since 1953 for this glacier (Pelto et al, 2013). In April the glaciers are typically covered head to toe by snow.  The last four months indicate a freezing level of nearly 900 m a record for the 1948-2016 period of record. An April 19th Landsat image indicates the snowline on Herbert and Mendenhall Glacier at 600 m. This is below the terminus of Lemon Creek Glacier at 800 m.  Near the Juneau Icefield the Long Lake Snotel site at 260 m in elevation had its snowpack drop from 64 cm water equivalent to 38 cm water equivalent in the last month.

wolverine base camp

USGS Wolverine Glacier Base Camp last week with field work underway. 

juneau icefield april 2016

April 19 Landsat image of the southwest side of the Juneau Icefield.  Snowline indicated by Purple arrows. M=Mendenhall, H=Herbert, L=Lemon Creek and T=Taku Glacier.

For Mount Baker, Washington the freezing level from January-April 20 was not as high as the record from 2015, but still was 400 m above the long term mean.  Observations at the base of Easton Glacier, one of our key glaciers in the North Cascades, indicate that the snowpack has declined from a depth of 4.8 m to 3.4 m during the first three weeks of April. This is mainly due to compaction, versus snow water equivalent loss, but still represents the rapid densification that occurs as snowmelt begins in earnest.

easton 2016 snowpack april

April 2016 image from icefall on Easton Glacier at 2500 m above (Adam Dunn) and in August below same area (Jill Pelto). 

DSC07209

 

Belopolskijbreen Retreat Generates Terminus Split, Svalbard

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

BELOPOL COMPARE

Belopolskijbreen comparison in 1990 and 2014 Landsat images.  Red arrow is the 1990 terminus location, yellow the 2014 extent of the a bedrock ridge separating the two lobes of the glacier, and purple arrow an area of thinning at the head of the glacier. 

Most of the attention on Svalbard glaciers goes to the larger tidewater glaciers, which collectively having been losing volume rapidly.  Belopolskijbreen in Sorkappland near the southern tip of Svalbard a land based glacier that we examine here using Landsat images from 1990 to 2014.  The glacier is adjacent to Olsokbreen a rapidly retreating tidewater glacier. In 1990 and in the TopoSvalbard maps indicate the glacier terminating in proglacial lakes A and B. The snowline is restricted to the very top of the glacier.  With limited retained snowpack anywhere, the glacier will thin and retreat significantly.  In the middle of the glacier near the red arrow is a bedrock ridge that 700 m into the glacier.  By 2014 the bedrock ridge has extended to the yellow arrow, an additional 700 m.  The glacier has retreated 500 m from Lake A and 650 m from Lake B. The retreat of approximately 500 m across a 4 km wide glacier front plus the expansion of bedrock in the middle, represents more than 2 square kilometers of area lost.  This retreat will continues as the snowline has been limited to the very top of the glacier in 2013, 2014 and 2015. The 2013 Landsat image below indicates the snowline with purple dots.  The snowline is above 375 m with the top of the glacier at just over 400 m.  The glacier has 10% snowcover retained at a maximum, the minimum needed for equilibrium is 50%.

Nuth et al (2013) determined that the glacier area over the entire archipelago has decreased by an average of 80 km2 per year over the past 30 years, a 7% reduction. In the most recent period 1990-2007, terminus retreat was larger than in an earlier period from 1930-1990, while area shrinkage was smaller. Svalbard is host to 163 tidewater glaciers with a collective calving front of 860 km (Błaszczyk et al, 2009). Blaszczyk et al. (2013) reported the total area of the glacier cover lost in Hornsund Fjord area from 1899–2010 was approximately 172 square kilometers, which is just north of Sorkappland.

belopol

TopoSvalbard map of Belopolskijbreen, terminating at Lake A and B. Red arrow marks ridge separating glacier terminus into two lobes.

belopol 2013sn

2013 Landsat images.  Note the snowpack limited to the very top of the glacier, purple dots

Goddess of Light (Kolahoi) Glacier Showing Mortality, Kashmir Retreat 1993-2015

On By mspeltoIn glacier climate change, Glacier Observations, Himalaya glacier retreat4 Comments

kolahoi compare

Kolahoi Glacier comparison in Landsat images from 1993 to 2014.  Kolahoi Glacier is the northern glacier, East Kolahoi Glacier the other noted glacier.  Red arrows indicate 1993 terminus locations, and yellow arrows the 2014 terminus locations. 

The Kolahoi Glacier in Kashmir is known as the—”goddess of light”—Gwash Brani  (NatGeo, 2010). The glacier descends the north side of the mountain with two tongues of the glacier merging above the terminus in 1993. The glacier drains into the Liddar River and then the Jhelum River system.  The Jhelum River has several large operating hydropower stations and several more under construction including the Karot Hydropower Project a 720 MW run of river project.  Jeelani et al (2012) observed that the Liddar Watershed derives 60% of its runoff from snowmelt and just 2% from glacier ice melt.  They further report that the Liddar watershed has 17 glaciers covering an area of 40 km2 in 2008. The climatic warming in the region has led to mass wasting of Kolshoi Glacier and retreat.  From 1970 to 1990 there was a cooling trend of about −0.02°C per year followed by the time period from 1991 to 2010 with the highest increasing trend of 0.07°C per year (Jeelani et al 2012) .  Tayal (2011) observed the detachment of the two glacier branches and a loss of 2-3.5 m of ice thickness due to ablation in the lower reach of the glacier.

jhelum_river_basin

Hydropower Projects in Jhelum Basin.

From 1993 to 2001 there is limited retreat of Kolahoi Glacier and East Kolahoi Glacier, though both glacier fronts become narrower.  By 2006 Kolahoi Glacier has retreated to near the base of a steeper slope.  The glacier remains heavily crevassed in the region above the icefall within 1 km of the terminus, Point A. By 2014 the glacier has retreated to the top of the steeper slope between two bedrock knobs at 3650 m, total retreat from 1993 to 2014 is 700 m.  Crevassing above the slope, at Point A, that used to be an icefall has become limited since 2006 and before.  The reduction in velocity indicates retreat will continue. The western tributary of the Kolahoi has developed a separate termini from the main glacier after 2001, single vertical red arrow.. The East Kolahoi Glacier has retreated 300 m.  The lower 300 m of Kolahoi Glacier is thin and relatively uncrevassed.  This indicates the retreat will continue.  This region has its highest precipitation from January through April and highest runoff in June and July.  Hence, the glacier is not a summer accumulation type like glaciers to the east in the Himalaya. The retreat is similar to that of Samudra Tupa Glacier and Durung Drung Glacier.

kolahoi ge 2014

Google Earth image from 2014 of Mount Kolahoi and its main glaciers flow directions indicated.

kolahoi 2001

2001 Landsat image of Kolahoi Glacier

koahoi 2015

2015 Landsat image of Kolahoi Glacier

kolahoi terminus compare

Google Earth image of the terminus area outlined in blue of Kolahoi Glacier in 2006 and 2014. 

kolahoi-fig-0006

Image of the terminus of Kolahoi Glacier in 2010 from Jellani et al (2012)

 

Nansen Ice Shelf, Antarctica Calving Event Occurs April 2016

On By mspeltoIn Antarctic Glacier retreat, Glacier Observations1 Comment

nansen compare calving

Nansen Ice Shelf just north of Dryglaski Ice Tongue on April 2 with evident rift,blue arrows, and after calving two icebergs on April 7, A and B. Images from NASA MODIS

The NIWA reported a calving event from the Nansen Ice Shelf on April 11, 2016.  They are concerned about a mooring in Terra Nova Bay in front of the ice shelves. The area of the Nansen Ice Shelf is 1500 square kilometers, these icebergs have a combined estimate of approximately 250 square kilometers.  This is a substantial calving event for such a small system. Below is an image of the Nansen Ice Shelf on January 1, 2014 and January 1, 2016.  This illustrates the Terra Nova Bay polyna that develops every summer, and affects sea ice dynamics, and certainly the ice shelf. The former lacks a notable rift, the latter exhibits the rift that would lead to calving, the rift had formed in late 2013, but is still not evident in imagery of the resolution of MODIS.  NIWA had been watching this expanding rift for signs of calving.  NASA had warned in March that calving was imminent and had been monitoring the ice shelf to determine the affect of tides on the ice shelf dynamics.  The rift is beautifully shown by NASA in its growth from 2013 to 2015. Such rifting and calving can be part of stable dynamics as on Stange Ice Shelf or an indicator of instability as in the case of Verdi Ice shelf.

nansen comapre

Nansen Ice Shelf in January 2014 and January 2016.

terra nova 1999

Google Earth image of the region in 1999 indicating several significant rifts.

North Cascade Winter Snowpack 2016, 33rd Field Season Approaches

On By mspeltoIn glacier climate change, Glacier Observations, North Cascade Glaciers

This 2016 winter has proved much different than in 2015.  In 2015 exceptional warmth led to record low snowpack despite above average precipitation.  The warmth is illustrated using the North American Freezing Level Tracker for our Sholes Glacier site. The highest mean level by far is 2015, 500 m above average versus 180 m above average this winter.  The low snowpack combined with a long warm melt season in 2015 led to the highest mass losses from North Cascade glaciers in our 32 years of observations.

2016 freezing level

Freezing Levels for the November-March period at Sholes Glacier in the North Cascades.

A key date for snowpack assessment has always been April 1.  As a result there is good data set from six of the invaluable  USDA SNOTEL sites in the North Cascades since 1946.  A comparison of snowpack water equivalent (SWE) and total precipitation yield a ratio of SWE retained on April 1 to total precipitation.   The result is the ratio between SWE and precipitation, snowpack storage efficiency has been in decline,  as noted by Mote et al (2008) and Pelto (2008). The best long term precipitation stations in the region are Diablo Dam and Concrete, we use the average of the two. The storage efficiency ratio  was a minimum in 2015 at only 19% of precipitation retained as snowpack.  In 2016, 43% of precipitation has been retained leading to snowpack that is 10% above the mean for the 1984-2015 period.Winter precipitation over the period has a positive trend and SWE a negative trend. This declining ratio led Jon Riedel of the North Cascades National Park Service to observe that we now need 120% of average precipitation to achieve average snowpack. It is interesting to note that 2014, 2015 and 2016 had quite similar November-March total precipitation.  With 2016 slightly exceeding 2014 for snowpack.

In 2014 the glaciers had a poor year, not due to low snowpack but to high melt season temperatures.  What will transpire in 2016 will be the focus on our 33rd consecutive annual field season monitoring North Cascade glaciers. In the last 10 days warm weather in the region has led to significant snowpack melt.  At low elevation sites snowpack depth and SWE have decreased by 20% at sites like Trinity 2930 feet. Just 10 miles away at Lyman Lake at 5980 feet the snow depth decreased from 170 inches to 142 inches, but SWE has not declined.  As is typical this early snowmelt period leads to percolation and either refreezing or storage within the snowpack. This is still an important ripening that must occur before SWE can drop.  Typically SWE reaches a maximum at the elevations of glaciers between May 1 and 10.  A 10 day warm period as has occurred may indicate an early peak, but April could also feature more snow storms that will lead to future increases. From Alaska to British Columbia  to Washington groups are heading into the field to assess snow depth on glaciers at the end of this winter season.  Snowpits, snow stakes emplaced last last summer and Ground Penetrating Radar will all be deployed.

swe-ppt ratio

Trends in winter precipitation November-march in the North Cascades , average of Concrete and Diablo Dam.  Mean SWE at six USDA SNOTEL station on April 1 (Fish Lake, Lyman Lake, Park Creek, Rainy Pass, Stampede Pass and Stevens Pass). Ratio of April 1 SWE and winter precipitation.

april 1 swe 84-16

Mean SWE at six USDA SNOTEL station on April 1 (Fish Lake, Lyman Lake, Park Creek, Rainy Pass, Stampede Pass and Stevens Pass.

DSC06954

Assessing snow depth on Easton Glacier using crevasse stratigraphy. 

galcier peak raising three hikers april 2016

Image above of Glacier Peak and below of Monte Cristo Peaks in the North Cascades on April 9, 2016 from a trip to Bedal Peak by raising3hikers at NWHikers.net. The blanket of snow remains deep. 

monte cristo

Neumayer Glacier, South Georgia, 5.6 km retreat 1999-2016

On By mspeltoIn glacier climate change, Glacier Observations, south georgia glacier retreat

 

neumayer 2016

Comparison of Neumayer Glacier in 1999 and 2016 Landsat images; red arrow indicates 1999 terminus locations, yellow arrows 2016 terminus locations. Purple arrows indicate upglacier thinning.

South Georgia sits amidst the circum Antarctic westerlies and its maritime climate leads to numerous glaciers. This region is famous for the endless march of storms parading around Antarctica . The island is south of the Antarctic Convergence, preventing any truly warm season from persisting. The cool glaciers covering a majority of the island and quite low equilibrium line altitudes. Neumayer Glacier is one of the largest tidewater glaciers on South Georgia. Sugden, Clapperton and Pelto (1989) noted the ELA of Neumayer Glacier at 550 m.

The BAS has a mapping function that provides glacier front positions since early in the 20th century. For Neumayer Glacier the 1938 position is 3.5 km down fjord from the 2006 position. There was essentially no retreat up to 1974 and limited retreat up to 1993. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980s. After 1980 most glaciers receded; some of these retreats have been dramatic.

Landsat Images from 1999 to 2016 indicates retreat of 5600 m from the red to the yellow arrow, this is 350 m/year. A glacier dammed lake along the north shore of the fjord no longer exists in 2016. The glacier appears to have retreated into a deeper section of the fjord then where it ended from 1970-2002. The glacier is on the verge of separation into two main tributaries. This will enhance calving from the glacier, and promote additional mass loss and retreat. This retreat will impact Konig Glacier to the north, which is connected to the Neumayer Glacier. Below the comparison of terminus location from 1989 to 2015 indicates a retreat of 6700 m.  NASA Earth has piggy backed on this assessment, with excellent recent imagery. Calving rate increases with water depth.  Calving rate increases with water depth and the degree of glacier flotation. Flotation depends on water depth, ice thickness and the number of pinning points. Pelto and Warren (1991) provided an expanded version of the water depth/calving relationship first quantified by Brown and others (1982). In the you would have never guessed it category, is the glacier retreat has been an aid to the rat population, as the glacier tongues used to corner populations.

BAS Glacier front map

neumayer compare

Comparison of Neumayer Glacier in 1989 and 2015 Landsat images; red arrow indicates 1989 terminus locations, yellow arrows 2015 terminus locations.

 

Stange Ice Shelf, Antarctica, Maintains Stability 1989-2016

On By mspeltoIn Antarctic Glacier retreat

 

 

stange-2016b

Stange Ice Shelf, Antarctica in 2016 Landsat image.  Five rift zones are mentioned two  by the southern ice front R3 and R4.  Two by the central ice front R1 and R2. Purple dots mark ice front and yellow and red arrow the 1989 frontal positions on the north and south side of Case Island

Holt et al (2014) provide an exemplary examination of the dynamics from 1973 to 2011 of Stange Ice Shelf  This ~8000 square kilometer ice shelf is at the base of the Antarctic Peninsula on its west side. With several ice shelf collapsing and indicating structural weakness, all should be examined, each will have a different story. They examined the ice shelf for the four key precursor symptoms of an ice sheet collapse.  1) Significant thinning due to surface or basal melt, which can structurally weaken the ice sheet.  2) Structural weakening along suture zones.  3) Sustained retreat and development of a concave front that has less connection to pinning points.  4) Increase in velocity.  Examples where weakness is evident are en Verdi Ice Shelf, Wordie Ice Shelf and Jones Ice Shelf to the north. Here we use Landsat imagery from 1989, 2003 and 2016 to examine the south and central ice front, which illustrates what Holt et al (2014) concluded that the ice shelf is currently stable.

stange map

From Holt et al (2014)

The northern portion of the Ice shelf did lose 384 square kilometers between 1973 and 2011, while the southern and central ice front region each gained, a combined 48 square kilometers (Holt et al., 2014: Figure 2).  Comparisons from 1989 to 2016 indicated very limited net ice front change from 1989 to 2016. The net change is 4% ice shelf area loss.  In the case of the southern and central ice front there is not a sustained retreat. For velocity the net change in Holt et al (2014: Fig. 4) indicates only one area of significant acceleration, just southeast of Case Island and running just north and west of Rift zone R3. Just south of this zone and R3 was a zone of declining velocity. Surface elevation change was not consistent temporally or spatially.  There was a net overall thinning of 0.17 m/year, a relatively minor amount (Holt et al, 2014: Fig. 5).  This is a region dominated by basal melt ablation, which has been the key loss for most ice shelves (Pritchard et al 2012).  A structural examination of rifting and suture zones indicated that most rifting had been persistent throughout the period.  The exception was on the boundary of the accelerating and decelerating ice near R3, that occurred after 2001 when the iceberg noted calved. In 1989 this yet to be created iceberg has rifts that indicate it will soon calve, and in 2003 it has calved and moved from the calving front. For most rift areas there is little change from 1989 to 2003 to 2016,  except for 3 where the degree of rifting has decreased. The overall assessment is that Stange Ice Shelf is currently stable, with none of the four precursor symptoms being widespread and significant spatially and temporally.

stange 1989

Stange Ice Shelf, Antarctica in 1989 Landsat image.  Five rift zones are mentioned two  by the southern ice front R3 and R4.  Two by the central ice front R1 and R2. Purple dots mark ice front and yellow and red arrow the 1989 frontal positions on the north and south side of Case Island. IB= Ice berg that calves in 2001

stange 2003

Stange Ice Shelf, Antarctica in 2003 landsat image.  Five rift zones are mentioned two  by the southern ice front R3 and R4.  Two by the central ice front R1 and R2. Purple dots mark ice front and yellow and red arrow the 1989 frontal positions on the north and south side of Case Island. IB= Ice berg that calves in 2001

New Zealand Glacier Change Index

On By mspeltoIn glacier climate change, Glacier Observations, New Zealand glacier3 Comments

 nzlake compare2

Terminus of Tasman, Mueller and Hooker Glacier terminus in Mount Cook 1972 map, no lake present.
Progalcial lakes forming in front of Tasman, Mueller and Hooker Glacier in 1990 above and 2015 Landsat images below. 
Red arrows are the 1990 terminus and yellow arrows the 2015 terminus locations.

 

Overview

The Southern Alps of New Zealand are host to over 3000 glaciers that owe their existence to high amounts of precipitation ranging from 3 to 10 m (Chinn, 1999). The list below examines the changes of 12 glaciers examined in a separate post. The NIWA glacier monitoring program has noted that volume of ice in New Zealand’s Southern Alps has decreased by 36% with the loss of 19.0 km3 of glacier ice, from 53.3 km3 in 1978 to 34.3 km3 in 2014 (New Zealand Govt., 2015). Volume loss in New Zealand glaciers is dominated by 12 large glaciers (Salinger and Willsman, 2008). More than 90% of this loss is from 12 of the largest glaciers in response to rising temperatures over the 20th century (Chinn, 1999).  In the 1972 map of the region there is no lake at the terminus of the Tasman Glacier, Mueller Glacier or Hooker Glacier; each are substantial in size by 2015. Each lake continues to expand and as glacier retreat continues .From 1977-2015 NIWA has conducted an annual snowline survey, in six of the last nine years the snowline has been significantly above average and three years approximately at the average (Willisman et al., 2015).  This has driven the widespread glacier retreat underway. In each case the retreat of the largest glaciers has been enhanced by the formation and expansion of lakes, in this newly developing lake district. Dykes et al., (2011) identify the role of glacier lakes in accelerating the retreat of Tasman Glacier.  The retreat of these glaciers has until recently been slowed by debris cover and the long low slope ablation zone segments  (Chinn, 1999).  Glaciers that lack debris cover and have a steeper slope have a more rapid response time, such as Fox Glacier and Franz Josef Glacier (Purdie et al., 2014).  These two glaciers have been in the news of late due to rapid retreat causing glacier tours of the lower reaches of the glacier unsafe.  NIWA reported that February of 2016 was the second warmest month of any month in New Zealand, which will drive snowlines higher and enhance glacier melt this year.

Many New Zealand glaciers are important for hydropower: Lake Tekapo and Lake Pukaki are both utilized for hydropower. Hooker Glacier, Mueller, Murchison and Tasman Glacier drain into Lake Pukaki, where water level has been raised 9 m for hydropower purposes. Water from Lake Pukaki is sent through a canal into the Lake Ohau watershed and then through six hydropower plants of the Waitaki hydro scheme: Ohau A, B and C. Benmore, Aviemore and Waitaki with a combined output of 1340 MW.  Meridian owns and operates all six hydro stations located from Lake Pūkaki to Waitaki. The reduction of glacier area in the region will reduce summer runoff into Lake Pukaki and this hydropower system.
gunn glacier 2006
Gunn Glacier in, 2006 above and 2012 below,Google Earth image.  Red arrows the 2006 terminus position yellow arrows 2012 terminus location. The glacier lost 25% of its area in six years. 

gunn glacier 2012
Individual Glacier Posts

Murchison Glacier   Tasman Glacier   Balfour Glacier

Mueller Glacier   Hooker Glacier   Salisbury Snowfield

Lyell Glacier     Douglas Neve    Gunn Glacier

Upper Volta Glacier  Donne Glacier

donne compare

Donne Glacier from 2003-2012 in Google Earth images.  Red arrow is the 2003 terminus and yellow arrow the 2012 terminus. A seven hundred meter retreat in a decade.