Category: Glacier Observations

Post detailing changes in a glacier

Hagafellsjokull, Iceland Reflects Langjokull Thinning & Retreat

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

hagafellsjokull-compare

Landsat comparison of the terminus of Hagafellsjökull from 2000 and 2016.  The red arrows are the 2000 terminus, the yellow arrows the 2016 terminus.  Purple arrows indicate upglacier thinning. 

Langjökull is the second largest iceap in Icalnd with an area of over 900 square kilometers. The mass balance of the icecap has been reported since 1997 and his lost over 1 m per year during this period (WGMS, 2016).  Pope et al (2010) noted that the icecap has lost an area of 3.4 ± 2.5 km2 yr-1 over the decade from 1997-2007.  Pope et al (2010) noted that the loss of ice volume confirms previously published predictions that Langjökull will likely disappear within the next 200 years if current trends continue. A key outlet of  Langjökull is  Hagafellsjökull which terminates in Hagvatn. Hagafellsjökull ended a sustained post Little Ice Age retreat in 1970.  The ensuing advance of approximately 1 km ended by 2000.  Here we examine Landsat imagery from 2000-2016 to identify recent changes in this outlet glacier.

In 2000 the glacier terminated on an island in Hagavatn, red arrow.  The east margin of the glacier featured several locations where secondary termini overflowed a low ridge on the east side of the glacier.  By 2006 the glacier had retreated 500-600 m from the island.  By 2016 the terminus had retreated across its entire width by 800-850 m, 50 m/year, yellow arrows.  A closeup view from the Iceland online map application illustrates the 2014 terminus red dots. The end of the glacier has a low slope, low velocity and is debris covered.  The western side has terminated on land during this entire period and has approximately the same retreat rate as the eastern half that still ends in the expanding lake. There is little evidence of iceberg release into the lake, which helps explain the similar retreat rate. The low slope and upglacier thinning noted at the purple arrows indicate the retreat will continue.  In 2014 the transient snowline reached near the head of the glacier at over 1100 m.  In 2000, 2006 and 2016 the snowline with several weeks left in melt season ranged from 859-950 m. The retreat is similar to that of Norðurjökull another outlet of the Langjökull and Porisjokull.

langjokull-south-outlet-ge-2010

Google Earth view of the terminus of Hagafellsjökull in 2014. Red arrow is the 2000 terminus position and yellow arrow the 2014 position.

 hagafellsjokull-ismap

Online Iceland Map Viewer indicating the terminus of Hagafellsjökull in 2014, red dots.

hagafellsjokull-tsl

2006 and 2014 Landsat images of Hagafellsjökull indicating the transient snowline off the image in 2014 and at 850 m in 2006.

Desolation Valley, Alaska, Conversion from Glacier to Lake

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

 

desolation-compare

Retreat of Desolation-Fairweather Glacier from 2010-2016 in Landsat images.  The red arrow indicates 2010 terminus positions, yellow arrow the 2016 terminus. Pink arrow a delta exposed by lake level lowering. D=Desolation Glacier.

Desolation Glacier flows west from the Fairweather Range into Desolation Valley where in 1986 it joined with the Fairweather Glacier flowing from the north and the Lituya Glacier flowing from the south to fill the valley with glacier ice.  This is no longer the case, the valley once known for its long relatively flat area of largely debris covered ice, is mostly a lake now.  The valley has developed along the Fairweather Fault. Molnia (2007) noted that the tidewater termini of Lituya Glacier advanced ∼ 1 km since 1920 and continued to advance up to 2000 as it built an outwash plain reducing calving. Larsen et al (2015) noted thinning rates of 3 m per year for the Desolation Valley from Desolation Glacier north to Fairweather Glacier in the last decade (1994-2013).  Alifu et al (2016) identified that Desolation Glacier and Fairweather Glacier have lost 2.6% and 2.2% of their glacier area, respectively from 2000-2012. Only minor surface area changes were seen in Lituya Glacier during this period. They also noted that the mean snow line altitude of Fairweather, Lituya and Desolation increased by 120–290 m. Since 2012 extensive ice loss of the Desolation-Fairweather complex has occurred.  This is similar to the large rise in the transient snowline/equilibrium line noted by Pelto et al (2013) on nearby Brady Glacier.

In 1986 The Desolation Valley was filled with glacier ice from Fairweather Glacier to Liutya Bay.  By 2010 the southern half of the valley from Lituya Glacier to the outlet of Desolation Glacier into the valley had opened up and the terminus of Desolation Glacier and Lituya Glacier were at the red arrows, this represented a 5.3 km section of glacier lost. In 2013 the northern half of the valley filled by the Desloation-Fairweather Glacier was breaking up but still ice filled.  The Google Earth image from 2014 illustrates how broken up.  By 2016 the collapse was total and the new terminus is at the yellow arrow a 5.5 km retreat since 2010, this is a loss of 6.5 square kilometers of ice. The lake level also dropped which led to exposure of a lacustrine delta that had been submerged in 2013 and 2014, pink arrow. The lake has expanded in area, but lost in mean depth.  Will this continue to be a lake with continued retreat or become a braided river valley as the Fairweather Glacier continues to thin and retreat?  Desolation Glacier is no longer calving and its retreat rate should slow.  The terminus of the Fairweather Glacier should continue to retreat via calving in a fashion similar to glaciers around the world terminating in extensive lakes. Just to the north the North Fork Grand Plateau Glacier also experienced a large recent retreat with Landsat imagery in 2013 and 2014 indicating extensive calving from 2013 to 2015 and a retreat of 3.0 km, 1.5 km/year.  Fingers Glacier  is another nearby glacier that also is experiencing widespread retreat.  More images of the region are in a field blog on the region.

desolatiion-1986-2013

Retreat of Desolation-Fairweather Glacier from 1986 and 2013 in Landsat images.  The red arrow indicates 2010 terminus positions, yellow arrow the 2016 terminus. Pink arrow a delta exposed by lake level lowering. D=Desolation Glacier.

desolation-breakup

Google Earth image from 2014 of the disintegrating debris covered glacier.

 

 

 

 

 

 

 

 

 

 

 

 

Ross Ice Shelf Shear Zone-Research Focus of Gordon Hamilton

On By mspeltoIn Glacier Observations

shear-zone-3

Satellite Image of the Shear Zone:  The crevasses do have a surface representation, but are not generally open. 

Gordon Hamilton lost his life on Saturday Oct. 22, 2016 conducting research in the shear zone between the Ross Ice Shelf and McMurdo Ice Shelf.  I had the pleasure of working with and reviewing Gordon’s work; hence, it seems important to elaborate on the research that had brought researchers to this cold and hazardous corner of our planet.

Peter Rejcek of the  Antarctic Sun provided an excellent context for this work two years ago.  The Ross Ice Shelf is the world’s largest ice shelf at ~470,000 square kilometers. This floating ice shelf buttresses many faster flowing outlet glaciers that feed into it. Removal of the ice shelf would allow these glaciers to accelerate as has been seen after other ice shelves are lost, which could lead to enough drainage of the ice sheet to raise sea level 4 or 5 meters. The Ross Ice Shelf is in turn stabilized by pinning points.  Such pinning points include Roosevelt Island and the shear zone. This shear zone represents a region of high shear and velocity change between the two ice shelves. Shear represents friction which helps pin the ice shelf. Gordon Hamilton was the principal investigator on a three-year project to map this shear zone and determine the mechanics. His hypothesis was without the shear zone the Ross Ice Shelf further south would slowly disintegrate.  Without the ice shelf a glacier like Byrd Glacier which drains an immense area, 1,070,000 square kilometers, of East Antarctica could double its speed. Gordon was quoted by Peter Rejcek “The places that really control the future of the ice sheet are hard-to-access places, like shear margins or the underside of the ice shelf or the middle of crevassed outlet glaciers,” he added. “It’s hard to get good data sets there”.  But that is exactly what he was continuing to do, getting the data that would us be able to model and forecast future behavior of the this region, which in turn is crucial to both the East and West Antarctic Ice Sheets.

 

shear-zone-field-area

Left: Landsat image of field area from Feb. 2016. Red arrows indicate shear zone. 

Right: MODIS image from Oct. 23, 2016 illustrating the shear zone, red arrows.

To understand what was happening required detailed mapping of the crevasses within the shear zone.  Gordon had noted that the sub-surface crevasses and the visible surface crevasses did not seem to match up well in 2014.  This suggested an unusual flow pattern that could indicate instability within the shear zone. To examine and map the crevasses required detailed GPS and ground penetrating radar observations (GPR).  Because of the danger a pair of Robot rovers were utilized that could do the bulk of the mapping. The robot rovers were developed by Jim Lever, a mechanical engineer with the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL), in conjunction with the Thayer School of Engineering at Dartmouth College. The robots were used to prepare a safe route through the shear zone for the South Pole Traverse route and research in the area.  In fact the two teams last week were camped close by and working together to identify and re-mediate crevasses on the route. Arcone et al (2016) noted that the lightweight robotic vehicles had towed the GPR equipment on 100 parallel transects over a 28 km2 grid spanning the shear zone.

Some of their initial findings were presented at the AGU last fall (Kaluzienski et al, AGU, 2015).  The GPR surveys had allowed detailed mapping of the internal structures of the  Shear Zone.  This identified crevasses both in the upper firn and in accreted marine ice at a depth of approximately 170 meters. They also found a  spatial correspondence between near-surface and basal crevasses indicating that local lateral shear generated both. The distribution and orientation of the crevasses was consistent with predictions from a model.  This suggests that the mismatch in crevasses that would suggest instability is not present. This work also indicates that high-resolution modeling can be used to predict the locations of basal crevassing which will lead to an improved understanding of ice-shelf mass balance processes.  More images for the field area are in the field reports from Polartrec.

yeti-pb

Deploying the robot on the ice shelf Photo Credit: Jim Lever

Insights on crevasses and what they could tell us about ice sheet behavior was a passion for Gordon. In Greenland he had been examining ways to use crevasse development to understand changing dynamics of tidewater outlet glaciers.  The work conducted near Raven Camp after crevasses appeared in the skiway in 2012 was quite similar to the shear zone work in Antarctica. They installed stakes located with GPS including several continuously recording stations. This would allow determination of flow speed changes through the summer and if extensional flow had caused the formation of crevasse further inland. Understanding crevasses both for transportation needs and ice sheet behavior.

2009-crevasses-gis

Crevasse Mapping in Greenland from a preliminary study with Gordon Hamilton- from Jill Pelto

 

Tasermiut Fjord, Greenland loses its Glacier Connection

On By mspeltoIn glacier climate change, Glacier Observations, Greenland glacier retreat1 Comment

 

tasermiut-compare-ls

Landsat image sequence from 1999-2016.  Red arrows mark the 1999 terminus, yellow arrows the 2016 terminus and the purple arrow a tributary that detaches from Semitsiaq (S). Tasermiut Sermeq (T) retreats from the fjord. 

Tasermuit Fjord in southern Greenland is noted for its beauty, and until recently the fjord terminated at a glacier front. Currently no glacier reaches to the fjord. The retreat over the last two decades is similar to neighboring glaciers Kangersuneq Qingordleq and Qaleriq.  The loss of direct glacier connection is also occurring at Alangordlia. Here we examine Landsat images from 1999-2016 to observe glacier change. At the head of the fjord is Sermeq Tasermiut and on the east side is Sermitsiaq.

In 1999 the Sermitsiaq Glacier terminated at the eastern end of a small lake, red arrow.  Tasermiut Sermeq terminated in the fjord, red arrow.  By 2002 Sermitsiaq had retreated from the lake, while Tasermiut Sermeq still reached the fjord.  In 2013 Tasermiut Sermeq had retreated from the fjord and Sermitsiaq had retreated substantially from the lake and also had a significant tributary from the north detach, purple arrow. In 2016 Sermitsiaq has retreated 700 m since 1999, yellow arrow.  Biggs (2011) had noted a 610 m retreat of the glacier from 1987-2009, a slower rate than since 1999. Tasermiut Sermeq has retreated 300 m since 1999,and has a narrow steep tongue that will melt back quickly in the near future.

Murray et al (2015) examined 199 tidewater glaciers in Greenland and noted significant retreat of 188 of them. This is changing fjord dynamics, which will in the case of Tasermiut affect the marine biology, which has not been studied in any detail yet. Students on Ice 2014 Arctic Expedition provides exceptional imagery of this fjord and the Nanotarlik region.

tasermiut-ge-compare

Google Earth imagery of the region. illustrating the loss of fjord connection after 2009.

tasermiut-map

Map of the region 

2016 Field Season Results-North Cascade Glacier Climate Project

On By mspeltoIn climate change glacier retreat, Glacier Observations, glaciers salmon

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. April 1 snowpack at the key long term sites in the North Cascades was 8% above average. A warm spring altered this, with April being the warmest on record. The three-four weeks ahead of normal on June 10th, but three weeks behind 2015 record melt.  The year was poised to be better than last year, but still bad for the glaciers.  Fortunately summer turned out to be cooler, and ablation lagged.  Average June-August temperatures were 0.5 F above the 1984-2016 mean and 3 F below the 2015 mean. The end result of our 33rd annual field season assessing glacier mass balance in the North Cascades quantifies this. Our Nooksack Indian Tribe partners again installed a weather and stream discharge station below Sholes Glacier.

The primary field team consisted of myself, 33rd year, Jill Pelto, grad student UMaine for the 8th year, Megan Pelto, Chicago based illustrator 2nd year, and Andrew Hollyday, Middlebury College.  We were joined by Tom Hammond, NCCC President 13th year, Pete Durr, Mount Baker Ski Patrol, Taryn Black, UW grad student and Oliver Grah Nooksack Indian Tribe.  The weather during the field season Aug. 1-17th was comparatively cool.

Mass Balance: Easton Glacier provides the greatest elevation range of observations.  On Aug 2, 2016 the mean snow depth ranged from 0.75 m w.e. at 1800 m to 1.5 m w.e. at 2200 m and 3.0 m w.e. at 2500 m. Typically the gradient of snowpack increase is less than this.  There was a sharp rise in accumulation above 2300 m.  This is the result of the high freezing levels.  The mass balances observed fit the pattern of a warm but wet winter.  The high freezing levels left the lowest elevation glaciers Lower Curtis and Columbia Glacier with the most negative mass balance of approximately 1.5 m. The other six glaciers had negative balances of -0.6 to -1.2 m. This following on the losses of the last three years has left the glaciers with a net thinning of 6 m, which on glaciers averaging close to 50 m is a 12% volume loss in four years.  We anticipate with that this winter will be cooler and next summer the glaciers happier.  We will back to determine this.

Snowpack loss from Aug. 5-Sept. 22 is evident in the pictures below on Sholes Glacier.  Detailed snow depth probing, 112 measurements, of the glacier on August 5th allows determination of ablation as the transient snow line traverses probing locations from Aug. 5. GPS locations were recorded along the edge of blue ice on each of the dates. Ablation during this period was 2.15 m.

 

Terminus Change: We measured terminus change at several glaciers and found that a combination of the 2015 record mass balance loss and early loss of snowcover from glacier snouts in 2016 led to considerable retreat since August 2015.  The retreat was 25 m on Easton Glacier, 20 m on Columbia Glacier, 20 m on Daniels Glacier, Sholes Glacier 28 m, Rainbow Glacier 15 m, Lower Curtis Glacier 15 m.  The main change at Lower Curtis Glacier was the vertical thinning, in 2014 the terminus was 41 m high, in 2016 the terminus seracs were 27 m high.  The area loss of the glaciers will continue to lead to reduced glacier runoff. We continued to monitor daily flow below Sholes Glacier which allowed us to determine that in August 2016 45% of the flow of North Fork Nooksack River came from glacier runoff.  This is turns has impacts for the late summer and fall salmon runs.

 

Shatter & Shudder Glacier Retreat, British Columbia Lakes Form

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

shattter-terminus-compare

Red arrow is the 1985 terminus location and yellow arrow the 2016 terminus location.  Note the formatiion of new lakes at end of both glaciers. Purple dots is the transient snowline in August of each year.

Shatter and Shudder Glacier are at the eastern end of the Spearhead Range in Garibaldi Provincial Park, British Columbia. Osborn et al (2007) mapped the Little Ice Age extent of the glaciers compared to the 1990’s margins indicating a retreat of 300 m for Shatter Glacier and 700 m for Shudder Glacier (see below).  Koch et al (2009) identified the recession in area from 1928 to 1987 noting a 6% loss in Shatter Glacier and 22% loss for Shudder Glacier.  Koch et al (2009) identify an 18% loss in area from 1987-2005, indicating considerable recent change in the Park. Here we use Landsat imagery from 1985-2016 to update glacier change.

In 1985 there are no lake at the terminus of either Shatter or Shudder Glacier.  In 2002 a lake has formed at the terminus of Shudder Glacier, but not Shatter Glacier.  In 2016 both glaciers have proglacial lakes that have formed, and the terminus of both glaciers have retreated from the lakes.  This marks a retreat of 325 m on Shudder Glacier and 275 m on Shatter Glacier since 1985. Shudder Glacier retreated more rapidly in the first half of this period, while Shatter Glacier has experienced most of the retreat since 2005.

On Shatter and Shudder Glacier In 1987 the late August image indicates the snowline is at 2040 m, in mid-August 2015 the snowline is at 2250 m. In late August of 2014 the snowline was at 2120 m. In mid-August 2016 the snowline is at 2080 m. The higher snowlines are an indicator of mass loss for these glaciers that in turn drives retreat.  The region continues to experience significant loss in glacier area and development of many new alpine lakes with glacier retreat, five new lakes since 1987 just in this range with seven glaciers.  Spearhead and Decker Glacier are two other glaciers in the range that have developed new lakes since 1987. Nearby Helm Glacier is faring even worse.

 

shatter-tsl-compare

Landsat images from 1987, 2014 and 2015 indicating the transient snowline position at the purple dots on Shatter and Shudder Glacier.

spearhead-range-alpine-lakes-87-15

Pink Arrows indicate five new alpine lakes that have developed since 1987 as Spearhead Range glaciers have retreated

spearhead

Map of Spearhead Range glacier extent for LIA-Bold lines and 1987, light lines from Osborn et al (2007)

Storglombreen Glacier Loss, Norway

On By mspeltoIn glacier climate change, Glacier Observations, Norway glacier retreat1 Comment

storg compare Landsat

Landsat images from 199, 2002 and 2016 comparing glaciers draining into Storglomvatnet.  Red arrows indicate 1999 terminus locations, purple dots the snowline. 

Storglomvatnet has several glacier that terminated in the lake in 1999, Storglombreen Nord, Sorglombreen Sud and Tretten. This lake is the main reservoir, 3.5 billion cubic meters that feeds the 350 MW Svartisen Hydropower plant. The lake has an elevation of 585 m, while the power plant is at sea level. Paul and Andreassen,(2009)  examined glacier area and found overall almost no areal extent change from 1968-1999 of Svartisen region glaciers, including the three examined here.  Engelhardt et al (2013), note this was due to positive trends of winter balance between 1961 and 2000, which have been followed by a remarkable decrease in both summer and winter balances leading to an average annual balance of –0.86±0.15 m w.e.a–1 between 2000 and 2010 .Since 1999 there have been changes. The Norwegian Glacier Inventory  and the online digital atlas use this 1999 imagery and indicate glacier area  for Storglombreen Sud at 15.9 km2, for Storglombreen Nord  at 41.2 km2 and Tretten-nulltobreen at 5.9 km2.

In 1999 each of the glaciers reaches the lake shore at 585 m in four separate terminus fronts. The snowline in 1999 is at 1150 m. In early August 2002 the termini still reach the lake shore and the snowline is higher at 1250 m.  In 2001, 2002 and 2003 mass balance measurements by the Norwegian Water Resources and Energy Directorate, indicate the snowline reached the top of the glacier at 1580 m. In 2016 the glacier termini no longer reach the lake shore and the snowline is again at 1150 m. It is evident in the Landsat image above that Storglombreen Sud and Tretten-nulltobreen no longer reach the lake shore, the southern most and northern most termini and arrows.  The two termini of Storglombreen Nord no longer reach the lake, though this requires higher resolution Sentinel 2 images to illustrate. Retreat of Tretten-nulltobreen from 1999-2016 has been 200 m, of Storglombreen Sud 250 m and of Storglmbreen Nord 100-200 m. There was limited calving into the lake and the retreat from the lake will not significantly alter the retreat rate of the glacier.  The high snowlines of recent years will lead to continued retreat. The retreat here is much less than on Engabreen which shares a divide with Storglombreen Nord, Flatisen  or Blåmannsisen.

svartisen west

Map of the glaciers in the region from the Norwegian Glacier Inventory online map application, based on 1999 images.

storg 2016 sentinel

Sentinel 2 image of the glaciers of Storglomvatnet from August 2016.  Notice that none of the termini reach the lake shore. 

 

 

 

 

 

 

Winsvold, Andreassen and Kienholz (2014)

South Sawyer Glacier Retreat and Separation, Alaska

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

south sawyer terminus compare

Comparison of South Sawyer Terminus position and unnamed glacier just to the south.  Red arrows are the 1985 terminus and yellow arrows the 2016 position of each terminus. 

South Sawyer Glacier is a 50 km long tidewater glacier terminating at the head of Tracy Arm fjord in Southeast Alaska.  The winding fjord surrounded by steep mountains is fed by Sawyer and South Sawyer Glacier is home to stellar sea lions, humpback whales and harbor seals.  This combination makes it attractive for cruise ships.  Mike Greenfelder a Naturalist/Photography Instructor with Lindblad Expeditions suggested I examine this glacier, and he provided several images. I had a chance to observe the glacier in 1982 and 1984 and noted that the snowline of the glacier at 1125 meters by Pelto (1987), using Landsat images.  We also identified the water depth at the glacier front was 180-200 m and the velocity of the calving front in the 1980’s was 1800 m/year (Pelto and Warren, 1990).  Today the velocity had declined  to less than half of this, which is expected given that water depth at the front in the most recent charts from 1999 indicate 1985 terminus position water depth is 110 m (Elliot et al, 2012). This is deep but not as deep as in the 1980’s, the greater the water depth, the greater the degree of buoyancy at the front and the higher the calving rate. The glacier retreated 3.5 km from 1899-1967 and then experienced little retreat from 1967 to 1985 (Molnia et al, 2008). Larsen et al (2007) observed a rapid thinning of the Stikine Icefield during the 1948-2000 period.The retreat has been driven by rising snowlines in the region that has driven the retreat of North Dawes, Baird, Dawes and Sawyer Glacier. Here we use Landsat images to indicate from 1985-2016 to identify terminus change and recent snowline elevation.

The terminus has retreated 2300 m from 1985 to 2016, with little retreat from 1985 to 1996.  Of equal importance is the glacier now appears to be near the tidewater limit of Tracy Arm.  In the gallery of terminus images below from Mike Greenfelder, the 2005 and 2012 images illustrate a sharp increase in slope at Point B and red arrows in 2015 just the red arrows, 300 m from the ice front.  In 2016 the ice front is nearly to the base of this icefall. This represents a sharp rise in the bed of glacier causing an icefall.  Whether the bed is entirely above sea level is not clear. Just south of the main terminus is a separate glacier that in 1985 was the combination of two tributaries.  By 2016 the two glaciers have separated with a retreat of  4.5 km for the western arm and 3.8 km for the eastern arm.

In the gallery of snowline images it is evident that upglacier there are two tributaries that joined the main glacier in 1985, that no longer reach the glacier in 2016.  This is indicative of the higher snowlines and thinning glacier. The gallery of snowlines  indicate the last date during the melt season with clear imagery of the snowline.  In 1985 the snowline was at 1250 m, in 1996 the snowline was at 1400 m, in 2013 1400 m, in 2014 1600 m, in 2015 at 1400 m and in 2016 at 1650 m.  The images are close to the end of the melt season, but are a minimum elevation for the equilibrium line.  The snowline is averaging 300 m higher than it did in the 1980’s. The retreat of South Sawyer Glacier and its iceberg production will slow as the water depth at the front declines in the near future.  The retreat will continue due to the sharp rise in snowlines that has occurred which has led to significant thinning up to 1500 m noted by Larsen et al (2007). The retreat of neighboring non-calving glaciers emphasizes this point.

[ngg_images source=”galleries” container_ids=”27″ display_type=”photocrati-nextgen_basic_imagebrowser” ajax_pagination=”1″ template=”/nas/wp/www/sites/blogsorg/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/view/imagebrowser-caption.php” order_by=”sortorder” order_direction=”ASC” returns=”included” maximum_entity_count=”500″]

 

 

World Glacier Monitoring Service 30th Anniversary

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

Zemp_20160831-25

The numbers on the left y-axis depict quantities of glacial mass loss from the WGMS and sea level rise, and the suns across the horizon contain numbers that represent the global increase in temperature, coinciding with the timeline on the lower x-axis From Jill Pelto

The World Glacier Monitoring Service (WGMS) celebrated 30 years of achievement last week. I have had the privilege of being the United States representative to the WGMS and was an invited speaker for the Jubilee held in Zurich, Switzerland along with Matthias Huss, Wilfried Haeberli, Liss Marie Andreassen and Irene Kopelman. This post examines the important role that WGMS has and continues to serve under the leadership of Michael Zemp. The organization has been compiling, homogenizing and publishing data on glacier fluctuations and mass balance primarily from 1986-2013. WGMS remains the leading organization for the collection, storage and dissemination of information on the fluctuations of alpine glaciers. The resulting standardized collection of alpine glacier data that is archived by WGMS, is also leading to analysis efforts that otherwise would be hampered by limited data and lack of homogeneity to the data. Glaciers are recognized as one of the best climate indicators.  Mass balance data is the best parameter to measure on glaciers for identifying climate change, because of its annual resolution. The core of the WGMS data set has been frontal variations, which indicate longer response to climate as well as dynamic changes.  The key data set today provided by WGMS are the reference glaciers.

This set of glaciers has a 30-year continuous record of annual mass balance measured in the field, and each glacier also has geodetic verification.  This mass balance data set is featured on the Global Climate Dashboard at NOAA. I report the mass balance of two reference glaciers Lemon Creek Glacier in Alaska and Columbia Glacier in Washington.  Today the field based work is being increasingly supplemented and supplanted by remote sensing methods.  This data sets indicates a period of sustained mass balance loss, and glacier retreat that Zemp et al (2015) using WGMS data noted as historically unprecedented.  The most recent compilation publication is the Global Glacier Change Bulletin.

This data set is of particular value during this period of climate change and is already chronicling the disapperance of a number of glaciers in the data set. Glacier loss is not a process that has been well documented. The WGMS data set can be enriched by more data from expanding monitoring, reporting data from archives and simply adding the submission of data as a step in the research process for those monitoring alpine glaciers. The video of my presentation looking at 33 consecutive years of field work and sharing this data after compilation with the WGMS is below. The slides below are from the Jubilee presentations.

 

[ngg_images source=”galleries” container_ids=”32″ display_type=”photocrati-nextgen_basic_imagebrowser” ajax_pagination=”1″ template=”/nas/wp/www/sites/blogsorg/wp-content/plugins/nextgen-gallery/products/photocrati_nextgen/modules/ngglegacy/view/imagebrowser-caption.php” order_by=”sortorder” order_direction=”ASC” returns=”included” maximum_entity_count=”500″]

Moulins: Clarifying Impacts on Glacier Velocity

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

In the last week I have read three separate articles referring to glacier moulins as lubricating the bed of a glacier resulting in overall velocity increase, for example EOS (Aug. 2016), this is not generally accurate. Having spent considerable time observing moulins and reviewing some excellent studies that indicate their impact, it is worth noting again a more complete picture of the role moulins play.  This is a role that warrants considerable further examination. In 2008 and 2011 I wrote a piece indicating why this a generalization that is only sometimes accurate.  The key to increasing glacier velocity is high basal water pressure, not simply lots of meltwater.  Think of your car, if you have low oil pressure that is an issue for efficient running.  If you have high oil pressure that is ideal.  If you have high oil pressure and you add more oil that does not further lubricate the engine.  Delivering more water to the base of a glacier that already has lots of meltwater drainage will not typically lead to a significant acceleration.  A number of studies since 2008 have better illustrated this principle as it applies to ice sheets.

Ahlstrøm et al (2013) examined 17 Greenland glaciers and noted a pattern, “Common to all the observed glacier velocity records is a pronounced seasonal variation, with an early melt season maximum generally followed by a rapid mid-melt season deceleration”.  This indicates the Greenland glaciers are more like a typical alpine glacier and are susceptible to the forces that tend to cause alpine glaciers to experience peak flow during spring and early summer.  Those forces are the delivery of meltwater to the base of the glacier, when a basal conduit system is poorly developed.  This leads to high basal water pressure, which enhances sliding.  As the conduit system develops/evolves the basal water pressure declines as does basal sliding, even with more meltwater runoff.

This is what has been reported to be the case by Sundal et al (2011) in Greenland.  They found a similar early season velocity in all years, with a reduced velocity late in summer during the warmest years.  This suggested that a more efficient melt drainage system had developed, reducing basal water pressure for a longer period of time. The meltwater lubrication mechanism is real, but as observed is limited both in time and area impacted.  It is likely that, as on alpine glaciers, the seasonal speedup is offset by a greater slowdown late in the melt season.  Most observed acceleration due to high meltwater input has been on the order of several weeks, leading to a 10-20% flow increase for that period.

Moon et al (2014) examined 55 Greenland glaciers and found three distinct seasonal velocity patterns. Type 1 behavior is characterized by speedup between late spring and early summer with speed remaining high until late winter or early spring, with the principal sensitivity being to terminus conditions and position. Type 2 behavior has stable velocity from late summer through spring, with a strong early summer speedup as runoff increases and midsummer slowing, as the glacier develops an efficient drainage system.  Type 3 behavior has a mid-summer slowdown leading to a pronounced late summer minimum during the period of maximum runoff.  Velocity than rebounds over the winter.  The common behavior is then a slowdown during periods of peak runoff and moulin drainage.

Anderson et al (2011) noted that changes in velocity due to a 45% change in meltwater input were small 4-5% on Helheim Glacier.

Clason et al (2015) modelled development of moulins and their ability to deliver the water to the bed of Leverett Glacier.  This study illustrates the level of details that is being examined to better model meltwater routing, which will inform flow models as noted by EOS (2015).

Moulins increase meltwater flow to a glacier bed.  In areas where significant surface melt occurs, this tends to lead to an early melt season increase in basal water pressure and then velocity.  This is typically followed by a mid/late melt season deceleration with continued meltwater drainage through moulins.  The lubrication is hence, restricted in time, and if followed by a deceleration, does not necessarily lead to an increase in the overall glacier velocity.  Certainly in some cases moulins will increase overall velocity and in others not.

Looking Inside a Glacier

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

Here we provide a visual look inside a glacier in the North Cascades of Washington.  Glaciers are not all the same, but the key internal ingredients in summer typically are in varied ratios: ice, meltwater, sediment and biologic material.  In this case there are torrents of water pouring through the interior of the glacier, generated at the surface the day we are filming.  We do measure the discharge and velocity of these streams.  Once they drain englacially they are much slower as there are numerous plunge pools.  There are also plenty of water filled crevasses. Some of the streams have considerable sediment in them, usually large clasts given the high velocity and low bed friction.  In this case there are also a great many ice worms clinging to the walls of a water filled crevasse, and the walls of the stream channels.  All of this water than merges by the terminus into an outlet stream.  This again we measure.  On the glacier we are measuring melt and at the end of the glacier runoff provides an independent measure of this melt as well. The water then heads downstream supplying many types of fish enroute to the ocean.

The last three years have led to considerable mass loss of glaciers in the area.  This means less snowcover at the surface, which leaves less room for the ice worms to live and forces them into the meltwater regions.  This also leads to more supraglacial stream channels, which develop and deepen.  In many cases the streams deepen to the point that they become englacial. The increased ice area also should stress glacier ice worms as they live on algae, which resides largely in snow, which is less extensive and persistent in recent summers.

Glaciers in BAMS State of Climate 2015

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

Decrease in Glacier Mass Balance uses measurements from 1980-2014 of the average mass balance for a group of North Cascade, WA glaciers. Mass balance is the annual budget for the glaciers: total snow accumulation minus total snow ablation. Not only are mass balances consistently negative, they are also continually decreasing. Glaciers have been one of the key and most iconic examples of the impact of global warming.  

BAMS State of Climate 2015 asked me about featuring some of the glacier images for the cover, and I countered with a suggestion to utilize one of a series of paintings by Jill Pelto that illustrate the impact of climate change magnifying the impact of the data.  Below are sections of this years report that focus on glaciers.

Glaciers and ice caps (outside Greenland)

M. Sharp, G. Wolken, L.M Andreassen, A. Arendt, D. Burgess, J.G. Cogley, L. Copland, J. Kohler, S. O’Neel, M. Pelto, L.Thompson, and B. Wouters

Among the seven glaciers for which 2014-2015 annual mass balance have been reported, the mass balances of glaciers in Alaska and Svalbard (three each) were negative, while the balance for Engabreen Glacier in Norway was positive. The pattern of negative balances in Alaska and Svalbard is also captured in time series of regional total stored water estimates, derived using GRACE satellite gravimetry, which are a proxy for regional total mass balance (ΔM) for the heavily glacierized regions of the Arctic (Figure 3). Measurements of ΔM in 2014-2015 for all the glaciers and ice caps in Arctic Canada and the Russian Arctic also show a negative mass balance year. The GRACE-derived time series clearly show a continuation of negative trends in ΔM for all measured regions in the Arctic. These measurements of mass balance and ΔM are consistent with anomalously warm (up to +1.5ºC) summer air temperatures over Alaska, Arctic Canada, the Russian Arctic, and Svalbard in 2015, and anomalously cool temperatures in northern Scandinavia, particularly in early summer (up to -2ºC). The warmer temperatures led to higher snowlines in the aforementioned regions as seen in images below.

clephane bay compare

Baffin Island Ice Cap near Clephane Bay indicate limited snowpack in 2015

frostisen compare

Frostisen Ice Cap, Svalbard with limited 2015 snowpack.

Alpine Glaciers

M.Pelto

Preliminary data for 2015 from 16 nations with more than one reporting glacier from Argentina, Austria, Canada, Chile, Italy, Kyrgyzstan, Norway, Switzerland, and United States indicate that 2015 will be the 32nd consecutive year of negative annual balances with a mean loss of -1169 mm for 33 reporting reference glaciers and -1481 mm for all 59 reporting glaciers. The number of reporting reference glaciers is 90% of the total whereas only 50% of all glaciers that will report have submitted data thusfar. The 2015 mass balance will likely be comparable to 2003, the most negative year at -1268 mm for reference glaciers and -1198 mm for all glaciers.

The cumulative mass balance loss from 1980-2015 is 18.8 m, the equivalent of cutting a 20.5 m thick slice off the top of the average glacier (Figure 1).  The trend is remarkably consistent from region to region (WGMS, 2015).  The decadal mean annual mass balance was -261 mm in the 1980’s, -386 mm in the 1990’s, –727 mm for 2000’s and -818 mm from 2010-2015.  The declining mass balance trend during a period of retreat indicates alpine glaciers are not approaching equilibrium and retreat will continue to be the dominant terminus response (Zemp et al., 2015). The recent rapid retreat and prolonged negative balances has led to many glaciers disappearing and others fragmenting (Pelto, 2010; Carturan et al, 2015).

columbia compare

In South America seven glaciers in Columbia, Argentina and Chile reported mass balance. All seven glaciers had losses greater than 1200 mm, with a mean of -2200 mm.  These Andes glaciers span 58 degrees of latitude.

In the European Alps, mass balance has been reported for 14 glaciers from Austria, France, Italy and Switzerland.  All 14 had negative balances exceeding 1000 mm, with a mean of -1865 mm. This is an exceptionally negative mass balance rivaling 2003 when average losses exceeded -2000 mm.

In Norway mass balance was reported for six glaciers in 2015, all six were positive with a mean of 780 mm.  This is the only region that had a positive balance for the year. In Svalbard six glaciers reported mass balances, with all six having a negative mass balance averaging -675 mm.

In Alberta, British Columbia, Washington and Alaska mass balance data from 17 glaciers was reported with a mean loss of -2590 mm, with all 17 being negative. This is the most negative mass balance for the region during the period of record.  From Alaska south through British Columbia to Washington the accumulation season temperature was exceptional with the mean for November-April being the highest observed.

In the high mountains of central Asia six glaciers from Russia, Kazakhstan, and Kyrgyzstan reported data, all were negative with a mean of -660 mm.

Columbia Glacier having lost nearly all of its snowcover by early August had its most negative mass balance of any years since measurements began in 1984