Falcon Glacier, British Columbia Wings Clipped by Climate Change

On By mspeltoIn British Columbia glacier retreat1 Comment

Falcon Glacier in 1985 and 2019 Landsat images indicating the 2000 m retreat.  Red arrow is 1985 terminus location, yellow arrow the 2019 terminus location. I=icefall locations joining the glacier.

Falcon Glacier in southwest British Columbia drains east from the Compton Neve into the Bishop River, which then joins the Southgate River. The Southgate River is one of three major watersheds emptying into the head of Bute Inlet. The Southgate River is known for the large runs of Chum Salmon. The area was the focus of a proposed Bute Inlet hydropower, that at present is no longer being pursued.  The region has experienced large negative mass balances 2000-2018 (Menounos et al 2018), that is driven retreat of many glaciers in the immediate area such as Bishop Glacier and Klippi Glacier.  Here we examined Landsat images from 1985 to 2019 to determine the response to climate change of Falcon Glacier.

In 1985 Falcon Glacier terminated at 980 m and was over 10 km long (red arrow).  There were two icefalls (I) feeding the glacier along with the two principal tributaries.  By 2002 the glacier had retreated 800 m, with narrow ponding in front of the terminus.  The two icefalls were still active and the medial moraine extending to the terminus had increased prominence. By 2015 the glacier had retreated another 800 m and the two icefalls are barely connected to the main glacier.  The snowline is higher in 2015 at 1850 m.  By 2019 Falcon Glacier had retreated 2000 m, losing 20% of its length since 1985.  The eastern icefall no longer rejoins the main glacier.  The western icefall is barely connected.  The snowline in early August 2019 is already at 1850 m indicating a limited accumulation area again. The high snowlines and continued expansion of bedrock areas even at 2000 m indicates the glacier will continue its rapid retreat.

Falcon Glacier in 2002 and 2015 Landsat images indicating the 2000 m retreat.  Red arrow is 1985 terminus location, yellow arrow the 2019 terminus location. I=icefall locations joining the glacier.

Map of Falcon Glacier indicating flow direction and icefalls (I). 

Nordenskjold Glacier, South Georgia Retreat Accelerates

On By mspeltoIn south georgia glacier retreat

Nordenskjold Glacier in 1993 and 2019 Landsat images.  Red arrow is the 1989 terminus location, yellow arrows the 2019 terminus location. Purple arrow is a tributary that has separated. Point #1 and #3 is expanding bedrock ribs.  Point #2 is an impounded glacial lake.

Nordenskjold Glacier is a tidewater glacier flowing into Cumberland East Bay on the east coast of South Georgia, Island.  Cook et al (2010) and Gordon et al (2008) noted a pattern island wide with many calving glaciers having the fastest retreat.  Gordon et al., (2008) observed that larger tidewater glaciers remained in relatively advanced positions from the 1950’s until the 1980’s, followed by significant recession,  this retreat was delayed on Nordenskjold Glacier until 2000. The map below from the British Antarctic Survey indicates the slow retreat from 1957-1998 and a more rapid retreat since. Here we use Landsat imagery from 1989-2019 to identify changes.

In 1989 the glacier terminated at approximately the same location as in 1957. Vegetation extended quite close to the terminus with a minimal trimline or recently deglacated zone evident. At Point #1 and #3 are bedrock ridges that generate medial moraines. At Point #2 is a glacial lake impounded by a secondary terminus. At the purple arrow is a tributary glacier joining the main glacier. By 1993 there has been a limited retreat exposing some newly deglaciated unvegetated terrain adjacent to the shoreline and glacier terminus. There was limited additional retreat up to 2000. This is unusual as the neighboring glaciers had all retreated substantially by 2000. By 2016 the glacier had retreated substantially, ~900 m. The tributary at the purple arrow no longer reaches the main glacier. At Point #2 the impounded lake has expanded slightly and is open water. The snowline is also at 500 m above Point #1 and #3.  In 2019 the snowline is again above 500 m. The area of bedrock at Point #1 and #3 has expanded significantly indicating glacier thinning, and greater ablation at this elevation. The terminus has retreated an average of 1250 m from 1989-2019. There is a significant trimline and recently deglacited terrain on the western shore of the bay.

The retreat is much less than on Neumayer, Twitcher or Hindle Glacier. The upglacier thinning suggests this process will continue, with a 3.2 km wide calving front in water of unknown depth calving will continue to be a key driver of retreat.

Nordenskjold Glacier in 1989 and 2016 Landsat images.  Red arrow is the 1989 terminus location, yellow arrows the 2019 terminus location. Purple arrow is a tributary that has separated. Point #1 and #3 is expanding bedrock ribs.  Point #2 is an impounded glacial lake.

Map of terminus change from the British Antarctic Survey map platform

Taku Glacier, Alaska Retreat Begins: A Two Century Long Advance Reversed by Climate Change

On By mspeltoIn alaska glacier retreat10 Comments
Taku Glacier in 2016 and 2019 Sentinel 2 images.  The Hole in the Wall Tributary  (HW) is upper right, Taku Glacier main terminus (MT). Yellow line is the 2016 terminus location.  The arrows denote locations where thinning is apparent as the area of bare recently exposed bedrock has expanded. A closeup is below.  Pink and brown areas between blue ice and yellow line in 2019 indicates retreat.

The Taku Glacier is the largest outlet glacier of the Juneau Icefield in Alaska.  Taku Glacier began to advance in the mid-19th century and this continued throughout the 20th century. At first observation in the 19th century the glacier was calving in deep water in a fjord.   It advanced 5.3 km between 1890 and 1948 moving out of the fjord into the Taku River valley, see maps below (Pelto and Miller, 1990).  At this time calving ceased resulting in positive mass balance without the calving losses.  The glacier continued to advance 2.0 km from 1948-2013 (Pelto, 2017). The advance was paralleled by its distributary terminus, Hole in the Wall Glacier.  This advance is part of the tidewater glacier cycle (Post and Motyka, 1995), updated model by Brinkerhoff et al (2017)  .  At the minimum extent after a period of retreat the calving front typically ends at a point of constriction in fjord width and or depth that limits calving.  With time sedimentation in front of the glacier reduces water depth and calving rate, allowing the glacier to begin to advance. In the case of the Taku Glacier after a century of advance the glacier had developed a substantial proglacial outwash and moraine complex that had filled in the fjord and the glacier was no longer calving, images below from 1961 and 1981 illustrate this.  This allowed the advance to continue through the rest of the 20th century and into the 21st century.  The slowing of the advance in the latter half of the 20th century has been attributed to the impedance of the terminus outwash plain shoal (Post and Motyka, 1995; Pelto and Miller, 1990). There is a concave feature near the terminus with an increase in crevassing where the push impacts flow dynamics as seen at black arrow in 1975 and 1998 images below. In 1980’s the Taku Glacier’s accumulation area ratio was still strong enough for Pelto and Miller (1990) to conclude that the Taku Glacier would continue to advance for the remaining decade of the 20th century, which it did.

Beginning in 1946 the Juneau Icefield Research Program began annual mass balance measurements that is the longest in North America. In conjunction with JIRP and its first director Maynard Miller we compiled and published an annual mass balance record in 1990.  From 1990 to the present in conjunction with JIRP and Chris McNeil we have continued to compile and publish this annual mass balance record (Pelto et al 2013).  This mass balance record has been updated as of April 2020 (McNeil et al 2020). Much of the remarkable data record of JIRP has this month been made accessible to the public, particularly through the efforts of Seth Campbell, JIRP director, Scott McGee, survey team director and Chris McNeil, mass balance liaison with USGS.

The ELA in 2018 and 2019 in Landsat images, purple dots indicate the record high snowlines for the 1946-2019 period that occurred both in 2018 and again 2019, Pelto (2019)  

Taku Glacier is one of the thickest known alpine temperate glacier, it has a maximum measured depth of 1480 m and its base is below sea level for 40-45 km above the terminus (Nolan et al 1995).   Moytka et al (2006) found that the glacier base was more than 50 m below sea level within 1 km of the terminus, and had deepened substantially since 1984. This suggests a very long calving retreat could occur. The glacier had a dominantly positive mass balance of +0.42 m/year from 1946-1988 and a dominantly negative balance since 1989 of  -0.34 m/year (Pelto et al 2013). . This has resulted in the cessation of the long term thickening of the glacier.  On Taku Glacier, the annual ELA (end of summer snowline altitude) has risen 85 m from the 1946-1988 period to the 1989-2019 period.  During the 70+ year annual record the ELA had never exceeded 1225 m until 2018, when it reached 1425 m ( Pelto (2019) ).  In 2019 the ELA again has reached a new maximum of 1450 m (see above images). Contrast the amount of the glacier above the snowline in 2018 and 2019 to other recent years that had more ordinary negative balances (see Landsat images below).

In 2008 and 2012 JIRP was at the terminus, creating the map below.  There was no change at the east and west side of the margin since 2008 and 55 to 115 m of advance closer to the center. The glacier did not advance significantly after 2013, and did not retreat appreciably until 2018. The Taku Glacier cannot escape the result of three decades of mass losses, with the two most negative years of the record being 2018 and 2019. The result of the run of negative mass balances is the end of a 150+ year advance and the beginning of retreat. Sentinel images from 2016 and 2019 of the two main termini Hole in the Wall Glacier right and Taku Glacier left. The yellow arrows indicate thinning and the expansion of a bare rock trimline along the margin of the glacier. The Hole in the Wall terminus has retreated more significantly with an average retreat of ~100 m.  The Taku main terminus has retreated more than 30 m along most of the front.  A terminus change record has been published as of April 2020 (McNeil et al 2020).

The retreat is driven by negative balances, mainly by increased surface melt.  The equilibrium flow of the Taku Glacier near the long term ELA for the 1950-2005 period was noted by Pelto et al (2008). This occurred during a period of glacier thickening, average profile velocity was 0.5 md-1  (Pelto et al 2008). Since 1988 the glacier has not been thickening near the snowline as mass balance has declined slightly (Pelto et al 2013). The remarkable velocity consistency measured by JIRP surveyors led by Scott McGee each year at profile 4 has continued.  It is below this profile that surface ablation has reduced the volume of ice headed to the terminus.

All other outlet glaciers of the Juneau Icefield have been retreating, and are thus consistent with the dominantly negative alpine glacier mass balance that has been observed globally (Pelto 2017).  Now Taku Glacier joins the group unable to withstand the continued warming temperatures.  Of the 250 glaciers I have personally worked on it is the last one to retreat. That makes the score climate change 250, alpine glaciers 0.

1890 United States Coast Guard Map indicating deep water in the fjord in front of Taku Glacier. 

 

Map of terminus change from Lawrence (1950).

 

Taku Glacier aerial photograph from US Navy in 1948.  Still minor calving on right (east side).

 

Taku Glacier in 1961 photograph indicating calving had ended. 

 

Taku Glacier in 1981 photograph with the well developed outwash plain (Pelto).

 

Map of Terminus Change from Miller and Pelto (1990)

 

Maynard Miller image of Taku Glacier and Norris Glacier in 1975, not concave flexure point at black arrow.

 

Photograph of Taku Glacier and Norris Glacier in 1998, not concave flexure point at black arrow (Pelto)

 

JIRP terminus survey map of 2008 and 2012 surveys. 

 

 

Equilibrium line altitude (ELA) from 1946-2019.

 

ELA in 2013, 2014, 2015 and 2017 in Landsat images.

 

This is a view across the glacier accumulation area that until 2018 had always been snowcovered at the end of summer (Pelto).

 

Ofhidro Glacier, Chile Retreat 1986-2019

On By mspeltoIn chile glacier retreat

Ofhidro Glacier glacier terminus change an accumulation zone changes from 1986-2019 in Landsat images.  Red arrow=1986 terminus, yellow arrow=2019 terminus change, orange arrows expanding bedrock areas and purple dots snowline. 

Ofhidro Glacier is an outlet glacier on the northwest corner of the Southern Patagonia Icefield (SPI), that has a northern and southern arm terminating in a proglacial lake. Sakakibara and Sugiyama (2014)a examine the terminus change and velocity of SPI glaciers the northern arm retreating 50 m per year from 1985-2011 and the southern arm 100 m/year 1985-2011.  They also noted a decline in velocity Here we examine Landsat imagery from 1986-2019 to identify the change.

In 1986 the southern arm extended across the proglacial lake to the shallows of the western shore. The northern arm had been retreating in a narrower valley with a comparatively consistent width.   In 1998 the southern arm in the broader lake reach had collapsed, a retreat of 1800 m.  The northern arm had a retreat of 200 m.  The snowline was at m.  In 2015 the southern arm has retreated into a narrower valley, and the northern arm has retreated to a turn to the south in the valley.  The orange arrows indicate the expansion of bedrock as the glacier thins.  By 2019 the southern arm has retreated 2800 m (88 m/year) and the northern arm has retreated 1800 m (56 m/year).   Jaber et al (2019)  noted a thinning of 0.5 m/year from 2000-2012 increasing to 1.2 m/year from 2012-2016.  Most of the thinning being in the valley tongues of each arm. There is an area of continuous exposed bedrock more than 3 km long.  This fits the observations of  Willis et al (2012) who observed that between February 2000 and March 2012 that SPI was rapidly losing volume and that thinning extends even to high elevations.   The retreat of this glacier is similar to that of Lucia Glacier and Gabriel Quiroz Glacier to the east.

Ofhidro Glacier glacier terminus change an accumulation zone changes from 1998-2015 in Landsat images.  Red arrow=1986 terminus, yellow arrow=2019 terminus change, orange arrows expanding bedrock areas and purple dots snowline.

Ofhidro Glacier image from 2015. Notice the trimlines and narrowing of both terminus tongues.  Orange arrow indicates new bedrock knob.

Orsabreen, Svalbard Retreat leads to Lake Tripling in Size

On By mspeltoIn svalbard glacier retreat

Response of Orasbreen (O), Glopeken (G) and Holmstrombreen (H) to climate change as indicated by 1995 and 2019 Landsat images.  Red arrow is 1995 terminus, yellow arrow 2019 terminus, pink arrows a deepening supraglacial stream channel and purple dots the snowline.

Orsabreen terminates in an expansing prolgacial lake, Trebrevatnet, that is shared with a glacier it has separated from Holmstrombreen. The glacier shares an accumulation zone with Kronebreen, a glacier that is experiencing rapid retreat, and is fast flowing (How et al 2017). The high discharge of Kronebreen indicates a high volume of accumulation above 650 m in the shared accumulation zone, the Holtedahlfonna.   Nuth et al (2010) from 1965-2007 reported the mean mass balance of  Svalbard glaciers, excluding Austfonna and Kvitøya, as  −0.36 m yr−1 . They noted that Orsabreen had less volume loss −0.24 m yr−1 and did have an increase at higher elevation. Ruppel et al (2017) observed annual accumulation of 0.9 m w.e. at 1100 m on Holtedahlfonna from 2005-2015.  Trebrevatnet expands both through glacier retreat and the melt out of ice cored moraine that comprises much of its margin, they observed 0.9 m of annual melt of the dead ice moraine areas (Schomacker and Kjaer, 2007).

In 1995, Trebrevatnet has an area of 4.0 km2 the terminus of Holmstrombreen, Glopeken and Orsabreen merge, separated by medial moraines.  In 2000 Holmstrombreen has retreated allowing Trebrevatnet to expand westward, while the medial moraine between Orsabreen and Glopeken still extends across the valley between Orsabreen and Trebrevatnet.  The snowline in 2000 is at 550 m.  In 2017 the snowline is at 600 m.  Glopeken, Homstrombreen and Orsabreen have retreated into separate valleys.  The medial moraine between Glopeken and Orsabreen has melted away.  In 2019 the snowline is at 500 m, Trebrevatnet has expanded to an area of 13.5 km2, more than tripling in area.  This is due primarily to the 2200 m retreat of Orsabreen.  The moraine melt out has expanded the length of the lake from 2.3 km to 7.5 km.  The thinning of the lower Holmstrombreen is evident by the deepening of the supraglacial stream indicated by the pink arrows in the 2000 and 2019 images.  A closeup view of the terminus from TopoSvalbard from prior to 2010 indicates both a deeply incised supraglacial stream indicating relative stagnation of the terminus (purple arrows), extensive crevasses that have become rifts near the terminus (green arrows) and the ice cored moraine that is now gone, blue arrows. This portion of the glacier has now been lost.  In 2019 the lowest 1 km of the glacier is relatively stagnant and poised to be lost. The tongue of the glacier below 550 m is too large to be supported by the smaller accumulation area above this feeding from the Holtedahlfonna. The retreat here is less than most of the tidewater glaciers in Svalbard such as Hinlopenbreen or Paierbreen, but similar to lake terminating glaciers like Gandbreen.

Response of Orasbreen (O), Glopeken (G) and Holmstrombreen (H) to climate change as indicated by 1995 and 2019 Landsat images.  Red arrow is 2000 terminus, yellow arrow 2017 terminus, pink arrows a deepening supraglacial stream channel and purple dots the snowline.

TopoSvalbard map and image of the Orsabreen terminus area and expansion of Trebrevatnet. Light blue arrows indicate ice cored medial moraine, light green arrows indicate rifts, and purple arrows a deep supraglacial channel.

Gilkey Glacier Retreat Leads to Rapid Lake Expansion in 2019

On By mspeltoIn alaska glacier retreat

Gilkey Glacier in 1984 and 2019 Landsat images indicating retreat of 4300m, tributary separation and 5 km2 lake expansion. A=Terminus tongue, B=Battle Glacier, G=Gilkey Glacier and T=Thiel Glacier.

Gilkey Glacier draining the west side of the Juneau Icefield has experienced dramatic changes since I first worked on the glacier in 1981.   The Gilkey Glacier is fed by the famous Vaughan Lewis Icefall at the top of which Juneau Icefield Research Program (JIRP) has its Camp 18 and has monitored this area for 70 years. Here we examine the changes using Landsat images from 1984, 2014, 2018 and 2019.  Landsat images are a key resource in the examination of the climate change response of these glaciers (Pelto, 2011). The August 17th 1984 image is the oldest high quality Landsat image, I was on the Llewellyn Glacier with  JIRP on the east side of the icefield the day this image was taken. JIRP was directed by Maynard Miller at that time and by Seth Campbell now.

In 1984 Gilkey Glacier terminated in a new proglacial lake that had  and area of 1.5 km2 (#1). At #2 Thiel and Battle Glacier merged and then joined Gilkey Glacier. Arrow #3 and #4 indicates valleys which tongues of the Gilkey Glacier flow into, at #3 the glacier extended 1.6 km upvalley.  At arrow #4 the glacier extended 1.5 km up Avalanche Canyon.  At #6, #7 and #9 tributaries flow into the Gilkey Glacier.  At #8 Antler Glacier is a distributary glacier terminus that spilled into a valley terminating short of Antler Lake.

By 2014 the proglacial lake had expanded to 3.65 km2 as the glacier has retreated 3200 m.  Thiel and Battle Glacier have separated from Gilkey Glacier and from each with a retreat of 2600 m for Thiel Glacier and 1400 m for Battle Glacier. The glacier no longer flows into the valley at #4. Tributaries at #6 and #9 no longer reach Gilkey Glacier.  At #7 there is not a direct flow connection, but is still an avalanche connection.  At #8 Antler Glacier has retreated 2200 m.

In 2018 and 2019 the snowline on the Juneau Icefield has been the highest of any year since observations began in 1984.  This will accelerate mass loss and lead to continued extensive retreat.  In 2018 the snowline was at 1600-1650 m on Sept. 16. In 2019 the snowline on Gilkey Glacier was 1650-1700 m on Sept. 10.  In July of 2019 the terminus tongue of the glacier reached across the junction of the Gilkey and Battle Valley, separating the two proglacial lakes.  By September 10, the glacier tongue had broken off leading to the two lakes joining expanding the size of the proglacial lake to 6.5 km2. The terminus has retreated 4300 m since 1984, while the lake has increased in size by more than 400%. The retreat will continue leading to additional lake expansion just as is occurring at Meade and Field Glacier.

The expansion of Gilkey Lake into the Battle Valley in 2019 Landsat images.

Gilkey Glacier in 1984 and 2019 Landsat images indicating retreat of 4300m, tributary separation and 5 km2 lake expansion. A=Terminus tongue, B=Battle, Bu=Bucher, G=Gilkey, T=Thiel, V=Vaughan Lewis. Snowline=purple dots.

Gilkey Glacier in 2014 and 2018 Landsat images indicating retreat, snowline elevation and lake expansion. 

 

Glacier Crevasses As A learning Tool

On By mspeltoIn glacier climate change, Glacier Observations3 Comments

Guest Post by Clara Deck

Instagram: @scienceisntsoscary

 

Crevasses on mountain glaciers are large cracks in the ice which often propagate from the surface downward. The initial break will happen when stress exceeds the inherent ice material strength. This article will focus on surface crevasses, though this basic physical understanding also applies to basal crevasses or large-scale rifts in ice sheet and shelf settings.

 

In mountain glacier systems, crevassing is likely to occur as ice flows over bedrock “steps.” Imagine you are baking a pie, and it is time to mold your pie crust to the pan. You must be very careful when bending the dough around the pie pan, because it may crack if you fold it too much or too suddenly.

Glaciers are the same way, and so another driver for crevasse formation is ice flow speed up in these areas. Other factors that could be at play are roughness of the underlying bed or drag along valley walls. The above photo of Rainbow Glacier shows a complex surface of crevassed and smooth areas, which hints to a similarly complex underlying bed.

During the 2019 field season of the North Cascades Glacier Climate Project, we measured these crevasses in a few different ways. Seven field seasons ago, Jill Pelto began collecting data on crevasse depth. She uses a cam line, which is essentially a weighted tape measure, to determine total crevasse depth on each glacier. This photo shows Jill measuring a crevasse on Easton Glacier. She tries to analyze crevasses in similar regions of the glaciers from year to year to achieve a cohesive dataset which could be useful on a long-time scale. This data has the potential to shed light on important glacial changes and how they may relate to regional warming or shifts in precipitation patterns in the North Cascades. The data could also illuminate differences in the behavior of each individual glacier. Overall the number of crevasses has declined, in 2019 average depth on Easton Glacier was 10-15 m.

Another technique we used in the field is crevasse stratigraphy. Upon looking inside open vertically-walled crevasses in the accumulation zone, there are clear layers exposed on the crevasse walls. The layers are the remaining snow from each accumulation season, with the most recent winter’s snow on top. Using a rope marked at each decimeter, we work together to measure the depth of each exposed snow layer. These measurements give a pinpointed measurement of mass balance, and thus glacial health, throughout the past couple of years.

In some open crevasse features, you can see that many more years of stratigraphy are preserved, like in this photo on Easton Glacier. Each visible layer is from a year during which the amount of snowfall exceeded the summer melt, and there is no remaining evidence from years with higher melt than snow accumulation.

Other information we can gather from crevasses is related to the internal stresses in the ice. Crevasses are opened by pull-apart forces which act perpendicular to the trend of the crevasse.

If you are able to relate the crevasse orientations to the stress within the glacier, it is useful in evaluating the dominant stresses and how they change throughout the glacier spatially. Identifying the locations of crevasse groupings is also a valuable observation, as it reveals the areas with high stress, and may give clues as to where bedrock steps exist below the glacier.

Crevasses are often perceived as scary and have a negative connotation, and while they are hazardous to glacial travelers (always be VERY careful and have the correct gear when navigating crevasses), they are actually a sign of glacial productivity. A healthy glacier’s crevasses are frequent and deep, because thick, flowing ice generates high stress conditions.

The North Cascades Glacier Climate Project has observed glacial thinning due to lower rates of snowfall paired with more intense summer melt seasons over the past 36 years. This has led to a reduction in the number of crevasses in many areas. During summer 2019, the glaciers we visited in the North Cascades will lose up to 2 meters of snow from their surfaces to melting. It is likely that as this pattern continues, there will be even less surface crevassing on the glaciers.

Retreat of West Barun Glacier and Barun Tsho expansion, Nepal 1994-2018

On By mspeltoIn Himalaya glacier retreat

West Barun Glacier terminus retreat and lake expansion in 1994 and 2018 Landsat images. Red arrow is the 1994 terminus location, yellow arrow the 2018 terminus location, green arrow Seto Pohkari and purple dots the snowline.

The West Barun Glacier flows southwest from Baruntse Peak at 7100 meters ending at  Lower Barun Tsho (Barun Tsho) at 4500 meters. Comparison of Landsat images from 1994, 2000, 2015 and 2019 indicate the retreat of the glacier and expansion of the lake. In the early 1990’s the lake was observed to have an area of 0.7 km2 (ICIMOD, 2010). The importance of such lakes impounded in part by moraines, is the potential for glacier lake outburst floods (GLOF). The Lower Barun Tsho has no specific date for a GLOF observed. Rounce et al (2017) examined the risk posed by Lower Barun Tsho, part of which is another proglacial lake 3 km upstream, Seto Pohkari with an area of 0.41 km2 and it is considered to be a high hazard as the avalanche.  There are 33 buildings, 4 bridges and ~0-.8 km2 of agricultural land at risk of GLOF damage below Lower Barun Tsho (Rounce et al 2017) .

In 1994 the lake is 1100 m long and has an area of ~0.6 km2. By 2000 the lake was 1400 meters long and the area has increased to 0.9 km2.  The snowline in both 1994 and 2000 is ~5700 m.  In 2009 the lake was 2000 meters long and had an area of 1.4 km2 having doubled in size. By 2015 the lake is 2700 m long and has an area of ~1.6 km2.  Haritashya et al (2018) surveyed Lower Barun Tsho in 2015 and found a maximum depth of 205 m and a volume of 112.3 × 106 m3. In 2018 the maximum length of the lake is 2800 m and the area 1.7 to 1.8 km2.  The snowline in 2015 and 2018 is at 6000 m, which is above the mean elevation of the glacier, indicating mass balance loss.  In the 2009 Digital Globe imagery below, right half of image, the glacier is stagnant below the light green arrow. The medial moraines evident at the purple arrows indicate the area around 5700-5800 m that typically is in the ablation zone. The orange arrows indicate the outflow from Seto Pohkari.  The dark green arrows indicate the wide moraine band.  There is some melt out of this 1 km wide band resulting in lake expansion and pond development.  The lake length and area has doubled since 2000.  Glacier retreat has been 1500 m from 1994-2018. Haritashya et al (2018) expect faster growth and increasing risk from Lower Barun Tsho.  The beginning of a stagnant zone below the icefall, light green arrow below, indicates rapid retreat can continue. The changes here are repeated at many glaciers in this region including Lumding, Lhonak,  Yanong and Thulagi

Kirschbaum et al (2019) examined the cascade of hazard impacts that can work together to generate or accentuate geologic hazards in this regions including earthquakes, monsoon flood events, avalanches and GLOFs.

West Barun Glacier: Purple arrows indicate upper reach of lateral moraines, light green arrow the start of the stagnant zone below an icefall, orange arrows indicate the river draining the Seto Pohkari and dark green arrows indicate the partially ice cored moraine belt.

West Barun Glacier terminus retreat and lake expansion in 2000 and 2015 Landsat images. Red arrow is the 1994 terminus location, yellow arrow the 2018 terminus location, green arrow Seto Pohkari and purple dots the snowline.

Hutchinson Glacier, Greenland Releases New Island

On By mspeltoIn Greenland glacier retreat1 Comment

Cape Deichmann becomes an island as it disconnects from Hutchinson Glacier. Landsat images from 2010 and 2019.

The Hutchinson (H) and Polaric Glacier (P) region of East Greenland indicating three locations of island forming or about to form in 2010 and 2019 Landsat images.  Point #1 is Flado Island, Point #2 and Point #3 is Cape Deichmann

Ziaja and Ostafin (2019)  noted the formation of a new island at Cape Deichmann (3) due to recession of Hutchinson Glacier (H). Here we use Landsat images from 2010-2019 to examine the release of this island and other islands and pinning points  in the Hutchinson and Polaric Glacier area. This is one of a growing number of examples of glacier retreat leading to island formation.

In 2010 a tongue of Hutchinson Glacier connects to Cape Deichmann.  Hutchinson Glacier also connects to five other islands along its front, helping provide stability to the ice front.  Pinning points such as these islands reduce calving directly (Hill et al 2017), but also suggest limited water depth, which would reduce the impact of warm ocean water.  The center of Polaric Glacier also has Island #2 that provides stability.  At Flado Island (#1) the west margin of Polaric Glacier does not reach this island, but a melange of ice fills the space between the glacier front and the island, which does provide a degree of stability (Moon et al 2015). In 2012 there is no change in the Cape Deichmann or at Island #2.  Flado Island has lost its melange during this summer of exceptional warmth, but an ice tongue still reaches to within 1 km of the island.  In 2015 there is no change at Cape Deichmann or at Island #2.  The gap between the Polaric Glacier front and Flado Island is filled by a melange again.  In 2019 the Hutchinson Glacier ice tongue to Cape Deichmann is gone.  The ice front is now 0.6 km from the now Deichmann Island.  Island #2 is still embedded in the Polaric Glacier front.  Flado Island  has lost its melange in the warm summer of 2019, the central ice front of Polaric Glacier has also retreated 1.5 km, while the east and west margins changed little.  This will make it more difficult to develop a persistent melange of ice between the glacier front and Flado Island. There will be new island formed in the near future in this region.

The Hutchinson (H) and Polaric Glacier (P) region of East Greenland indicating three locations of island forming or about to form in 2010 and 2019 Landsat images.  Point #1 is Flado Island, Point #2 and Point #3 is Cape Deichmann

Flado Island with the removal of the melange in front of Polaric Glacier and the retreat of the glacier front from 2010-2019.

Map of the Hutchinson Glacier terminus region.

North Cascade Glacier Climate Project 2019, 36th Annual Assessment

On By mspeltoIn North Cascade Glaciers



The summer of 2019 found the North Cascade Glacier Climate Project in the field for the 36th consecutive summer monitoring the response of North Cascade glaciers to climate change.  This long term monitoring program was initiated partly in response to a challenge in 1983 from Stephen Schneider to begin monitoring glacier systems before and as climate change became a dominant variable in their behavior.

The field team was comprised of Clara Deck, Ann Hill, Abby Hudak, Jill Pelto and myself.  All of us have worked on other glaciers. The bottom line for 2019 is the shocking loss of glacier volume. Ann Hill, UMaine grad student observed, that “Despite having experience studying glaciers in southeast Alaska and in Svalbard, I was shocked by the amount of thinning each glacier has endured through the last two and a half decades.”  Glaciers are typically noted as powerful moving inexorably.  Clara Deck, UMaine MS graduate, was struck by “the beauty and fragility of the alpine environment and glaciers.”  Fragile indeed in the face of climate change. Abby Hudak, Washington State grad student, looked at both the glacier and biologic communities as under stress, but glaciers cannot migrate, adapt or alter there DNA.

Over the span of 16 days in the field, every night spent in the backcountry adjacent to a glacier, we examined 10 glaciers in detail. All glaciers are accessed by backpacking.  The measurements completed add to the now 36 year long data base, that indicate a ~30% volume loss of these glaciers during that period (Pelto, 2018). Here we review preliminary results from each glacier. Each glacier will have a mass balance loss of  1.5 -2.25 m, which drives continued retreat.  Columbia and Rainbow Glacier are reference glaciers for the World Glacier Monitoring Service, with Easton Glacier joining the ranks later this year. Below and above is the visual summary. Specific mass balance and retreat data will be published here and with WGMS after October 1.

Easton Glacier, Mount Baker.  Terminus has become thin and uncrevassed as a rapid retreat of 15 m per year continued, 405 m retreat since 1990.

Easton Glacier icefall at 2200 m typically has 1.8 m w.e. at the end of the summer, this year it will be 0 m. The overall mass balance will be ~2 m of loss.

Deming Glacier, Mount Baker has now receded over 700 m since our first visit 35 years ago.

On Lower Curtis Glacier a key accumulation source the NE couloir now shows bedrock. Overall by summers end ~25% of the glacier will retain snowcover, far short of what is needed to maintain its volume.

The Lower Curtis Glacier terminus continues to retreat at 8 m/year, but thinning and slope reduction has been more notable.  

In early August the majority of Sholes Glacier has lost its snowpack.  The thin nature of the terminus indicates the glacier is poised for continued rapid retreat that has exceeded 15 m per year during the last 7 years.

Runoff assessment confirmed ablation stake measurement of 11 cm of ablation/day from 8/6-8/8 on Sholes Glacier.

High on Rainbow Glacier there are still plenty of regions lacking snowcover, instead of a thick mantle of snowpack.

Rainbow Glacier was awash in meltwater streams, see video.  This area should have 1 m of snowpack left. Rainbow Glacier has retreated 650 m since 1984.

Just getting to each glacier does involve overcoming various miseries.

A transect across lower Coleman Glacier, Mount Baker indicates 38 m of thinning since 1988.

Limited snowpack remaining on Columbia Glacier, with six weeks of melt left. Lake in foreground expanded dramatically in last two years.  Retreat ~45 m from 2017-2019 and 210 m from 1984-2019, more than 10% of its length.

Upper basin of Columbia Glacier mainly bare of retained snowpack.

Ice Worm Glacier terminates in expanding lake.

Ice Worm Glacier continues to retreat at the top and bottom of the glacier.  Mass loss is leading to a more concave shape each year.

Daniels Glacier had a maximum snowpack of 1.75 m, instead of 4 m.

Foss Glacier measurements discontinued as it disintegrates, only 20% snowcover in mid-August.

Lynch Glacier less than 50% snowcovered with six weeks of melt left.

 

The team which completed over 1200 mass balance measurements, 40,000 vertical feet and 110 miles of travel across glacier clad mountains.

 

The Disappearance of Multiple Baffin Island Glaciers 2002-2019

On By mspeltoIn Canada glacier retreat2 Comments

Glaciers at Point A and B have melted completely away.

The commemoration of a single disappearing glacier in Iceland, Okjokull has brought attention to what is quite a common event this decade, glacier disappearance. Here we report on a number of glaciers in the southern part of the Cumberland Peninsula, Baffin Island  that have either disappeared or separated into several parts  from 2002-2019. Way (2015) noted that on the next peninsula to the west, Terra Nivea and Grinnell Ice Cap had lost 20% of their area in the last three decades. The retreat and disappearance of ice caps in the area have led to a INSTAAR project at UColorado-Boulder examining vegetation that had been buried and is now being exposed.  This year the high snowlines by early June have led to the near complete loss of snowpack across glaciers of the region.  The melt rate of the exposed ice is higher than that of the snowcovered portion of the glaciers.

In the first image a small valley glacier at Point A has melted completely away.  At Point B a small plateau glacier is gone.  At Point C a remanent is left, though it cannot survive long now.  Below  the slope glacier at Point F is gone.  The plateau glacier at point G is gone.  The niche glacier at point E has separated into three small parts.

Glaciers at Point F and G have melted completely away.

Glacier at Point H has melted completely away.

At Point H a plateau glacier has been lost. At Point I two interconnected glaciers have separated into five smaller glaciers. Below the plateau glaciers at Point J and L have been lost.  At Point K a combination icecap-valley galciers has now separated into three parts.  At Point M an interconnected ice cap now consists of of six small glacier parts. The plateau glacier an Point N has been lost.  The slope glacier at Point O has been lost.  The disintegration and separation has been noted at other locations in the region such as Coutts Ice Cap and Borden Peninsula.

Glaciers at Point J and L have melted completely away.

Glaciers at Point N and O have melted completely away.

Alpine Glaciers-BAMS State of Climate 2018

On By mspeltoIn climate change glacier retreat

Figure 1. Global Alpine glacier annual mass balance record of reference glaciers submitted to the World Glacier Monitoring Service, with a minimum of 30 reporting glaciers.

For the last decade I have written the section on Alpine Glaciers for the BAMS State of the Climate report, the 2018 report was published this week, below is the section on alpine glaciers.  The key data resources is  the World Glacier Monitoring Service (WGMS) record of mass balance and terminus behavior (WGMS, 2017), which provides a global index for alpine glacier behavior.  Glacier mass balance is the difference between accumulation and ablation, reported here in mm of water equivalence (mm).  Mean annual regionalized glacier mass balance in 2017 was -921 mm for the 42 long term reference glaciers , with an overall mean of -951 mm for all 142 monitored glaciers.  Preliminary data reported from reference glaciers to the WGMS in 2018 from Argentina, Austria, China, France, Italy, Kazakhstan, Kyrgyzstan, Nepal, Norway, Russia, Sweden, Switzerland and United States indicate that 2018 will be the 30th consecutive year of significant negative annual balance (.-200mm); with a mean balance of -1247 mm for the 25 reporting reference glaciers, with one glacier reporting a positive mass balance (WGMS, 2018).  This rate of mass loss may result in 2018 exceeding 2003 (-1246 mm) as the year of maximum observed loss. as a mean. This WGMS mass balance record has now been regionally averaged before determining the global mean, this has not been done yet for 2018, which will reduce the magnitude of the negative balance.

Ongoing global glacier retreat is currently affecting human society by increasing the rate of sea-level rise, changing seasonal stream runoff, and increasing geo-hazard potential (Huss et al, 2017).  The recent mass losses 1991-2010 are due to anthropogenic forcing (Marzeion et al. 2014).

The cumulative mass balance from 1980-2018 is -21.7 m, the equivalent of cutting a 24 m thick slice off the top of the average glacier (Figure 1).  The trend is remarkably consistent across regions (WGMS, 2017).  WGMS mass balance from 42 reference glaciers, which have a minimum 30 years of record, is not appreciably different from that of all glaciers at -21.5 m.  Marzeion et al (2017) compared WGMS direct observations of mass balance to remote sensing mass balance calculations, and climate driven mass balance model results and found that each method yields reconcilable estimates relative to each other and fall within their respective uncertainty margins. The decadal mean annual mass balance was -228 mm in the 1980’s, -443 mm in the 1990’s, –676 mm for 2000’s and – 921 mm for 2010-2018.  Glacier retreat reflects sustained negative mass balances over the last 30 years (Zemp et al., 2015).  The increasing rate of glacier mass loss  during a period of retreat indicates alpine glaciers are not approaching equilibrium and retreat will continue to be the dominant terminus response (Pelto, 2018).

Exceptional glacier melt was noted across the European Alps, leading to high snowlines and contributing to large negative mass balance of glaciers.  In the European Alps, annual mass balance has been reported from 17 glaciers in Austria, France, Italy and Switzerland.  All 17 had negative annual balances, with 15 exceeding -1000 mm with a mean of -1640 mm.  This continues the pattern of substantial negative balances in the Alps, which will equate to further terminus retreat.  Of 81 observed glaciers in 2017 in Switzerland, 80 retreated, and 1 was stable (Huss et al, 2018).  In 2017, 83 glaciers were observed in Austria,; 82 retreated, and 1 was stable.  Mean terminus retreat was 25 m, the highest observed since 1960, when mean length change reporting began (Lieb and Kellerer-Pirklbauer, 2018).

In Norway and Sweden, mass balance surveys with completed results are available for eight glaciers; all had negative mass balances with an average loss of -1420 mm w.e.  All 25 glaciers with terminus observations during the 2007-2017 period have retreated  (Kjøllmoen et al, 2018).

In western North America data has been submitted from 11 glaciers in Alaska and Washington in the United States.  All eleven glaciers reported negative mass balances with a mean loss of -870 mm.  The longest mass balance record in North America is from Taku Glacier in Alaska.  In 2018 the glacier had its most negative mass balance since the beginning of the record in 1946 and the highest end of summer snowline elevation at 1400 m. The North Cascade Range, Washington from 2014-2018 had the most negative five-year period for the region of the 1980-2018 WGMS record.

In the High Mountains of Asia (HMA) data was reported from ten glaciers including from China, Kazakhstan, Kyrgyzstan and Nepal.  Nine of the ten had negative balances with a mean of -710 mm.  This is a continuation of regional mass loss that has driven thinning and a slowdown in glacier movement in 9 of 11 regions in HMA from 2000-2017 (Dehecq et al 2018).

 

Figure 2. Taku Glacier transient snowline in Landsat 8 images from July 21, 2018  and September 16, 2018.  The July 21 snowline is at 975 m and the September 16 snowline is at 1400 m.  The average end of summer snowline from is m with the 2018 snowline being the highest observed since observations began in 1946.

References

Huss, M., B. Bookhagen, C. Huggel, D. Jacobsen, R. Bradley, J. Clague, M. Vuille,  W. Buytaert, D. Cayan, G. Greenwood, B. Mark, A. Milner, R. Weingartner and M. Winder, 2017a: Toward mountains without permanent snow and ice. Earth’s Future, 5: 418–435. doi:10.1002/2016EF000514

Huss, M., A. Bauder, C. Marty and J. Nötzli, 2018: Neige, glace et pergélisol 2016/17.  Les Alpes, 94(8), 40-45. (http://swiss-glaciers.glaciology.ethz.ch/downloadPubs/alpen_15-16_f.pdf).

Dehecq, A., N. Gorumelon, A. Gardner, F. Brun, D. Goldberg, P. Nienow, E. Berthier, C. Vincent, P. Wagnon, and E. Trouve, 2019: Twenty-first century glacier slowdown driven by mass loss in High Mountain Asia. Nature Geoscience 12, 22–27.

Kjøllmoen B., L. Andreassen, H. Elvehøy, and M. Jackson, 2018: Glaciological investigations in Norway in 2017. NVE Report 82 2018.

Lieb, G.K. and A. Kellerer-Pirklbauer ,2018: Gletscherbericht 2016/17 Sammelbericht über die Gletschermessungen des Österreichischen Alpenvereins im Jahre 2017. Letzter Bericht: Bergauf 2/2017, Jg. 72 (142), S. 18–25. (http://www.alpenverein.at/).

Marzeion, B., J. Cogley, K. Richter and D. Parkes, 2014: Attribution of global glacier mass loss to anthropogenic and natural causes. Science, 345(6199), 919–921, doi: 10.1126/science.1254702)

Marzeion, B., Champollion, N., Haeberli, W. et al.: Observation-Based Estimates of Global Glacier Mass Change and Its Contribution to Sea-Level Change. Survey of Geophys, 38: 105, doi: 10.1007/s10712-016-9394-y.

Pelto, M., 2018: How Unusual Was 2015 in the 1984–2015 Period of the North Cascade Glacier Annual Mass Balance? Water 10, 543, doi: 10.3390/w10050543.

WGMS 2017: Global Glacier Change Bulletin No. 2(2017). Zemp, M., and others(eds.), ICSU(WDS)/IUGG(IACS)/UNEP/UNESCO/WMO, World Glacier Monitoring Service, Zurich, Switzerland, 244 pp.: doi:10.5904/wgms-fog-2017-10.

WGMS 2018: Fluctuations of Glaciers Database. World Glacier Monitoring Service, Zurich, Switzerland. doi: 10.5904/wgms-fog-2018-11. http://dx.doi.org/10.5904/wgms-fog-2018-11

Zemp and others 2015: Historically unprecedented global glacier decline in the early 21st century. J. Glaciology, 61(228), 745-763, doi: 10.3189/2015JoG15J017.