Moulins: Clarifying Impacts on Glacier Velocity

On September 1, 2016September 2, 2016 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 August 22, 2016 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 August 2, 2016May 2, 2024 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.

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

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).

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

Thirty-third Annual North Cascade Glacier Climate Project Field Season Underway

On July 31, 2016May 2, 2024 By mspeltoIn climate change glacier retreat, glacier climate change, Glacier Observations, glaciers salmon, North Cascade Glaciers4 Comments

Base Map of the region showing main study glaciers, produced by Ben Pelto.

From President Reagan to President Obama each August since 1984 I have headed to the North Cascade Range of Washington to measure the response of glaciers to climate change. Specifically we will measure the mass balance of nine glaciers, runoff from three glaciers and map the terminus change on 12 glaciers. The data is reported to the World Glacier Monitoring Service. Three glaciers that we have monitored annually have disappeared since 1984.

In 2016 for Mount Baker, Washington the freezing level from January-April was not as high as the record from 2015, but still was 400 m above the long term mean. The snowpack on June 1st was three weeks behind last year’s record melt, but still three to four weeks of head of normal. July has been exceptionally cool reducing this gap. With all the snow measurement stations losing snowcover by July 1, the gap is uncertain until we arrive on the glaciers. This will not be a good year, but will be a significant improvement over last year, likely more in the 2012 or 2013 category. Each location is accessed by backpacking in and camping in tents.

We will first travel north to Mount Baker and the Easton Glacier, we will be joined by Oliver Lazenby, Point Roberts Press. We will then circle to the north side where I expect we will be joined by Jezra Beaulieu and Oliver Grah, Nooksack Indian Tribe. Jen Lennon from the Sauk-Suiattle Tribe and Pete Durr, Mount Baker Ski Patrol are also planning to join us here. When we head into Columbia Glacier Taryn Black from U of Washington will join us. The field team consists of Mauri Pelto, 33^rd year, Jill Pelto, UMaine for the 8^th year, Megan Pelto, 2^nd year, and Andrew Hollyday, Middlebury College. Tom Hammond, 13^th year will join us for a selected period.

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Aug.   1: Hike into Easton Glacier.
Aug.   2: Easton Glacier
Aug.   3: Easton Glacier
Aug. 4: Hike Out Easton Glacier, Hike in Ptarmigan Ridge
Aug.   5: Sholes Glacier
Aug.   6: Rainbow Glacier
Aug.   7: Sholes Glacier and/or Rainbow Glacier
Aug. 8: Hike out and into Lower Curtis Glacier
Aug. 9: Lower Curtis Glacier
Aug. 10: Hike out Lower Curtis Glacier- Hike in Blanca Lake Mail Pickup Maple Falls, WA 98266
Aug. 11: Hike in Columbia Glacier
Aug. 12: Columbia Glacier
Aug. 13: Hike out Columbia Glacier; Hike in Mount Daniels
Aug. 14: Daniels and Lynch Glacier
Aug. 15: Ice Worm Glacier
Aug. 16: Ice Worm Glacier, Hike out Mount Daniels-Hike out

Rainbow Glacier Not Fading Away, Glacier National Park

On July 12, 2016November 20, 2025 By mspeltoIn glacier climate change, Glacier Observations1 Comment

Rainbow Glacier is the third largest of the 25 remaining glaciers in Glacier National Park occupying an east facing cirque between 2650 m and 2330 m. The glacier drains into Quartz Lake a key lake for bull trout in GNP, which are threatened by both invasive lake trout and climate change (Jones et al, 2013). The National Park Serice and USGS have been established a glacier monitoring program that focuses on repeat photography, mass balance observations on Sperry Glacier and area change. GNP has lost the majority of the 150 glaciers that existed. The USGS reports that Rainbow Glacier had an area of 1.28 square kilometers in 1966 declining to 1.16 square kilometers in 2005, a 9.3% reduction. Has this slow rate of retreat continued? Here we examine Google Earth imagery from 1990-2013 and imagery taken by John Scurlock compiled by Glaciers of the American West at Portland State University,

In the Google Earth images from 1990, 2003 and 2013 the margin of the glacier in 1990 is in red and from 2003 is in orange. The margin of the glacier from 1990 to 2003 indicates modest recession averaging 25-30 m along the glacier front. This is part of the 9.3 % area loss noted by the USGS. In 2013 there is too much snowcover to identify the glacier boundary, glacier ice is exposed providing a minimum extent at the green dots. A comparison of 1990, 2005 and 2009 images, the latter from John Scurlock indicates the two primary terminus lobes. From 1990 to 2005 the southern lobe retreated 45 m and the northern lobe 25-30 m. There is not a significant change in either lobe from 2005 to 2009. The 2003, 2005 and 2009 imagery does indicate a low percentage of retained snowcover. This is the accumulation area ratio. Persistent low values indicate a glacier that cannot survive. In the case of Rainbow Glacier the accumulation area ratio is sufficient in most years to limit volume losses. In 2015 low snowpack exposed the terminus area,by late August the glacier still had 40% snowcover, indicating a negative mass balance, but not excessively negative. Glacier area updated to 2015 using the Landsat image the area is now between 1.00 and 1.10 square kilometers an approximately 20% area loss in 50 years. It is evident that this is the only late summer area of snow-ice in the watershed and is particularly crucial to the water budget in late summer and early fall. The slow retreat of the glacier is good for the bull trout in the watershed, Rieman et al (2007) indicated the sensitivity of the trout to stream temperatures. Glacier both increase flow and reduce stream temperature late in the summer. This is one glacier in the park that will not disappear by 2030 as has been often forecast. It will join Harrison Glacier in this category, while other glaciers in GNP continue to disappear.

1990 Google Earth image with two main terminus lobes indicated by red arrows.

2005 Google Earth image of Rainbow Glacier.

2009 John Scurlock image of Rainbow Glacier.

Lamplugh Glacier Recent Behavior and Landslide Source Area, Alaska

On July 7, 2016May 2, 2024 By mspeltoIn alaska glacier retreat, glacier climate change, Glacier Observations

Lamplugh Glacier before and after landslide, in Landsat 8 images, which is 7.5 km long and covers 17 square kilometers. L=Lamplugh, R=Reid and B=Brady Glacier.

A recent large landslide onto Lamplight Glacier on June 28, 2016 has been reported by KHNS. The landslide was triggered on the north slope of a steep unnamed mountainside on the west side of the Lamplugh Glacier, Glacier Bay, Alaska. The landslide has been estimated at 120 million tons by Colin Stark from Lamont Doherty . The region has been experiencing substantial retreat and glacier thinning such as on Brady Glacier, McBride Glacier. and Muir Glacier Loso et al (2014). However retreat on Lamplugh Glacier has been minimal since 1985, with USGS photographs from 1941 and 2003 indicating a 0.5 km advance. The glacier terminus in the last decade has thinned, narrowed and begun a slow limited retreat.The thinning of the glacier has been mapped by University of Alaska Fairbanks aerial flights since 1995 (Johsnon et al, 2013). They found from 1995 to 2011 that Lamplugh Glacier lost the least ice thickness per year compared to neighbors Ried and Brady Glacier, at -0.32 m/year, Ried at -0.5 m/year and Brady Glacier at -1.4 m/year Loso et al (2014). Because the glacier has been receding less than the neighbors it is not a natural choice for a retreat/thinning driven landslide. The snowline that is shared with Brady Glacier has risen 150 m during the 2003-2015 period (Pelto et al, 2013). This indicates increased melting at higher elevations. The greater melting on the north face of the failed slope could be a factor in the landslide. Southeast Alaska had its warmest spring ever this year, which is leading to higher area snowlines for this time of year on glaciers as noted at this blog three weeks ago on Brady Glacier. The North American Freezing Level Tracker notes an average freezing line 35 m above the mean for 1948-2015 and the highest on record in 2016 averaging nearly 1300 m.

Landsat image comparison of Lamplugh Glacier 1985, 2013, 2015 and 2016. The orange arrows indicate extensive surface moraine deposits. purple arrows the region below the slope where landslide was triggered. Point B trigger location and Point A a nearby cloud free location in each image.

A comparison of Landsat images indicates the trigger location Point B, with Point A being a location that is not cloud covered in any image for reference. The landslide through thin clouds is marked by purple arrows and purple dots on the July 6, 2016 image. The landslide extends approximately 9 km down glacier from the trigger site. Orange arrows indicate locations of extensive medial moraines due to erosion and possibly previous landslides. It is apparent that these areas stem from he west side of the glacier lower on the glacier than the current landslide trigger area. This area has not been the source of significant surface debris in the last 30+ years. Pelto et al (2013) noted that the snowline on neighboring Brady Glacier has risen by 150 m, this is the most pronounced impact of climate change to date for Lamplugh Glacier. The rising rate of landslides has been tied to increase melt in the Swiss Alps as permafrost on rock faces thaws. This post will be updated when clear Landsat imagery is available.

USGS Topographic map of the region overlay in Google Earth. Point B is the trigger point.

Freezing Level Tracker for Glacier Bay, AK

Suatisi Glacier Retreat, Mount Kazbek, Georgia

On June 27, 2016May 2, 2024 By mspeltoIn Caucasus Glacier retreat, glacier climate change, Glacier Observations

Comparison of Suatisi Vost (SV) and Suatisi Sredny (SS) in 1986 and 2015 Landsat images. The red arrow is the 1986 terminus and the yellow arrows the 2015 terminus. Point A and B are to areas of expanding bedrock amidst the glacier.

Suatisi Vost and Suatisi Sredny Glacier are two glaciers on the south flank of Mount Kazbek in northern Georgia. The region is prone to landslides and debris flows. On September 20, 2002 a collapse of a hanging glacier from the slope of Mt Dzhimarai-Khokh onto the Kolka glacier triggered an avalanche of ice and debris that went over the Maili Glacier terminus then slid over 15 miles (NASA Earth Observatory, 2002). It buried small villages in the Russian Republic of North Ossetia, killing dozens of people. The glacier runoff from Suatisi Glacier supplies the Terek River, which has a hydropower project under construction. The Dariali Hydroplant will have an installed capacity of 108 MW and is a run of river type plant near Stepantsminda, Georgia. This plant has suffered from two landslides in 2014 (Glacier Hub, 2014) that jeopardize its completion.

Shagadenova et al (2014) examined glaciers in the Caucasus mountains and found that from 1999/2001 and 2010/2012 total glacier area decreased by 4.7%. They also noted that recession rates of valley glacier termini increased between 1987– 2000 and 2001–2010, with the latter period featuring retreats averaging over 10 m/year. A positive trend in summer temperatures forced glacier recession (Shagadenova et al 2014). Here we examine changes in Suatisi Glacier from 1986 to 2015 with Landsat imagery.

In 1986 Suatisi Vost western side terminates at the top of deep canyon, red arrow. The eastern side of the terminus is on a flatter till plain. The area around Point B is all glacier ice. Suastisi Sredny terminates near the end of the valley it occupies in 1986. In the 2001 image a large debris flow/landslide has covered the eastern margin of Suatisi Vost surrounding the area of Point B, black arrow in 2001 image below. By 2010 the Google Earth image indicates significant retreat of Suatisi Vost and the debris flow below point B is a light gray color. The bedrock at Point B has expanded. By 2015 Suatisi Vost terminus has retreated 350 m since 1986, what is just as evident is the loss in width of the terminus in the 1986-2015 side by side comparison. Suatisi Sredny has retreated 450 m. The snowline is at an elevation of 3750-3800 m in 1986, 2010 and 2015. With the terminus at 3250 m and the highest elevation at 3950-4000 m, this is too high to sustain the glacier at its current size and retreat will continue. The debris cover has reached the terminus on the east side of the glacier by 2015. The changes are the same across the border in Russia, for example Lednik Midagrabin.

2010 Google Earth image of Suatisi Vost and Suatisi Sredny.

2001 Landsat image indicating the landslide covering surface of Suatisi Vost.

2015 Landsat image indicates Landslide deposit evolution, with movement downglacier and retreat, it is now close to the ice front on the east side of the margin.

Canadian Columbia Basin Glacier Spring 2016 Field Season (winter 2015-2016 Assessment)

On June 23, 2016May 2, 2024 By mspeltoIn Canada glacier retreat, glacier climate change, Glacier Observations

Guest Post by Ben Pelto, PhD Candidate, UNBC Geography, pelto@unbc.ca

During the spring season we visited our four study glaciers (Figure 1), which form a transect of the Columbia Mountains from the Kokanee Glacier in the Selkirk Range to the south, to the Conrad (Purcells) and Nordic (Selkirks) in the center, to the Zillmer of the Premier Range in the north. This post will explore the snowpack of winter 2016 across the Columbia Basin of British Columbia. For a video of the work this spring see here.

Figure 1. Map of the Columbia watershed basin in Canada. Our four study glaciers are red stars, and other glaciers are teal, per the Randolph Glacier Inventory. Major rivers and lakes are blue.

Winter 2015-2016 Snowpack Summary: Early winter, September-December, 2015 brought a number of Pacific storms, in contrast to 2013 and 2014 which featured few storms and relatively dry conditions. By January 1^st, snowpack across the province was near-normal, though a strong north-south gradient was observed, with above average snowpack in the south, average snowpack in central BC and well below average snowpack in the north (provincial snowpack was below normal Jan. 1^st, 2015; BC River Forecast Centre). February was warm and wet, with daily temperatures 1 to 5˚C above normal. By the beginning of March, snowpack was below average over most of the province north of Prince George and Bella Coola and near or above average to the south.

Snow continued to accumulate in March, but primarily at higher elevations due to above average freezing level heights. The height of freezing levels determines whether precipitation falls as snow or rain at a given elevation. Figure 2 shows that median freezing level height is 600 m above sea level for February at the Conrad Glacier, yet this February featured an average freezing level of 1300 m. This means that on average, in the month of February, snow fell above 1300 m and rain below 1300 m (of course this is an average and any one storm may be different). Most glaciers in the Columbia Mountains are located above 2000 m elevation, and in the winter of 2014-2015, freezing levels were often near or above the height of many of the peaks in the Columbia Mountains (3000 m), allowing for rain on snow events. Such events were reportedly rare in 2015-2016 winter until April/May, despite the fact that freezing level heights were record high for December-April (Figure 3).

Figure 2. Estimated freezing level height (elevation of 0˚C) for the Conrad Glacier from June 2015-May 2016. Note that February-April 2016 were at or above the 95^th percentile, meaning that there is less than a 5% chance that the freezing level heights will be that high given the data from 1948-2016 from which the median height is derived. Freezing levels are estimated from NCEP/NCAR Global Reanalysis data determined every six hours from 1948-present (North American Freezing Level Tracker).

Figure 3. Estimated mean freezing level height (elevation of 0˚C) for December-April from 1948-present for the Conrad Glacier (North American Freezing Level Tracker). Note that 2016 is the year of record. Freezing levels are estimated from NCEP/NCAR Global Reanalysis data determined every six hours from 1948-present.

Warm temperatures experienced in February continued through March and April across the province. By April 1^st, provincial snowpack was near-normal at 91% of average (Figure 4). The north-south gradient in snowpack grew, with the southern half of the province at or above average, and the northern half below average. Typically, May 1^st marks the peak of snow accumulation, and the melt season ensues. In 2015, the melt season began in mid-April, 1-3 weeks early. The 2016 melt season began earlier still, coming in late March/early April, 4-6 weeks early. Figure 5 shows that for the East Creek snow pillow near the Conrad Glacier, snowpack peaked in late March at around 120% of normal. Early maximum snow depth occurred due to a combination of dry, warm conditions. Typically, small precipitation events continue to add snow to alpine environments through April, and by swapping precipitation for dry, warm conditions, the snowpack began to decline in earnest in late March/early April.

Figure 4. British Columbia Snow Survey Map for April 1^st, 2016 (BC River Forecast Centre). Note that snowpack is roughly average in the south and 50-75% of average to the north.

Figure 5. Automated snow pillow data showing snow water equivalent (SWE, amount of water obtained if all the snow were to be melted per unit area) for East Creek, near the Conrad Glacier at 2004 m elevation. Note that peak SWE was 4-6 weeks early, but was around 120% of normal at the time, followed by rapid melting (BC River Forecast Centre).

By May 15^th, provincial snowpack was 39% of normal (Figure 6), a rapid decline from near average mid-winter snowpack. The north-south gradient also largely disappeared, though the three basins doing the best were the North and South Thompson, and the Upper Columbia at 70-86% of normal. Interestingly the Upper Columbia contains three of our four study glaciers. The May 15^th provincial average of 39% is a new record low (measured since 1980, BC River Forecast Centre). May 15^th snowpack is more typical of mid-June, indicating that snow melt is about four weeks ahead of normal. Most rivers are past the spring freshet, and discharge has begun to recede. The early freshet will put pressure on summer low flows across the province in snow-melt dominated rivers.

Figure 6. British Columbia Snow Survey Map for May 15^th, 2016 (BC River Forecast Centre). Note that snowpack that was roughly average in the south as of April 1^st is now well below average, and 50-75% of average to the north.

Field Work Overview—What we do: The primary goal of the spring field season is to determine how much snow fell over the winter on the four study glaciers. To do so, we take snow depth measurements using a heavy-duty avalanche probe. Snow depth is valuable information, but snow water equivalent (SWE; if you melted the snow in a given location, this would be the depth of water left behind per unit area) is the key to understanding how much water the snow contains. As you can imagine, a meter of powdery snow may contain only 10 cm of water, whereas a meter of wet snow may contain 30 cm of water. To measure density, we either take a snow core (think a tube of snow…like an ice core, except snow instead) and cut samples to weigh, or we dig a snow pit and then take samples from a wall in the snow pit. By combining measurements of density and depth, we are able to calculate SWE over the entire glacier. A typical end of winter SWE for a Columbia Basin glacier would be around 2 meters water equivalent, which would be roughly 4.5 meters of snow. By knowing how much snow covers the glacier, we know how much mass the glacier gained during the winter. At the end of the summer, we visit the glaciers again, and we measure how much melt occurred. By combining the winter accumulation of snow, and summer melt of snow and ice, we can determine how much the glacier gained or lost during the year. Figure 7 is an illustration of the product of depth and density measurements, and displays the relationship of elevation and accumulation over the Conrad Glacier. To see what we do watch: https://www.youtube.com/watch?v=wWYJdQnRq5k

Figure 7. Winter balance gradient for the Conrad Glacier in millimeters water equivalent per meter of elevation. Snow depth increases with elevation linearly, except in topographically complex areas, and nearest the top of the glacier (3200 m). Most of the glacier area is between 2000-3000 m.

We also are flying LiDAR surveys of our study glaciers. LiDAR is a laser sensor mounted on the bottom of an aircraft. The LiDAR unit essentially shoots rapid laser pulses, each pulse hits the surface and returns to the sensor. The time it takes for the signal to travel to the surface and back tells us the distance from the plane to the ground. With this data, we can make a detailed 3-D map of the glacier surface. This map is accurate to 10-25 cm in the vertical, and 50 cm laterally. By collecting this data biannually (spring and fall) we can determine how much snow fell, or melt occurred by subtracting subsequent 3-D maps from one another (e.g. by subtracting a September map from an April map of the same year, we can determine how much melt happened between the two flights). This data offers the ability to be able to cover far larger areas than is feasible for fieldwork.

By comparing our field data with the LiDAR data, we can determine whether the LiDAR is capturing the reality on the ground, and if the field data is able to represent spatial variability in snow depth. Our LiDAR flights occur over a day or two, whereas our field data are collected over a month. In order to directly compare both, we conduct a GPS survey of the glacier surface along the center of the glacier. We then compare the difference in elevation between the survey and the LiDAR and thus can account for any melt or accumulation that occurred in the intervening days or weeks.

This spring we also collected data using a Ground Penetrating Radar (GPR) which transmits high-frequency radio waves into the ice. When the radio waves encounter a buried object or a boundary between materials, then it is reflected back to the surface where a receiving antenna records the signal. In our case, the bedrock surface below the ice is the surface/boundary we are looking for. Once we pick out the bedrock surface from the data, then the signal and travel time are used to then determine the ice thickness (Figure 8). Ice thickness is important for determining how long a glacier will survive as well as putting current rates of ice loss in perspective. We still have a lot of data to collect and process, but it seems that smaller glaciers like the Nordic and Zillmer (~5 km²) are 50-90 m thick in general, larger glaciers like the Conrad (16 km²) average 100-200 m thick.

Figure 8. Ground Penetrating Radar data from the Conrad Glacier. The blue line marks the bedrock surface and the red line marks the airwave, which defines the glacier surface. Between the lines is glacier ice. The longer the signal travel time, the deeper the ice. For this line, the deepest point is 220 m ice depth, and the shallowest 115 m.

Field Season Stats:

Snow Depth Measurements: 161 discrete locations, 600+ individual measurements
Snow Pits and Cores (Density): 15
- The combination of snow depth and density allow for calculation of SWE
Ground Penetrating Radar (GPR) Distance (Ice thickness, Figure 3): Roughly 75 km
- GPR data allows for the calculation of ice thickness and ice volume
Distance Skied: 200+ km
Field Team Members: 8; UNBC, CBT, UBC, ACMG.
Glaciers with both field and LiDAR data: 4/4
GPS Surveys (to corroborate field/LiDAR data comparison): 4
Days on a Glacier: 18

Season Summary: Our data indicate that winter mass balance featured a north-south trend, with the Kokanee Glacier in the south equaling last year’s mass balance, the central region was 85% of 2015 (Conrad and Nordic), and the Zillmer in the north was around 80%. The 4-6 week head start on melt season led to higher snow density in 2016 than observed in 2015. This summer melt season will determine whether the record/near record negative mass balance seen across the region in 2015 will be rivaled or exceeded in 2016. The hot, early spring has primed the region to again break records.

Chutanjima Glacier Retreat & High Snowline, Tibet, China 1991-2015

On June 21, 2016May 2, 2024 By mspeltoIn china glacier retreat, climate change glacier retreat, glacier climate change, Glacier Observations

A comparison of three Tibet glaciers in 1988, 1991 and 2015 Landsat images. Red arrows are the 1988 terminus position, yellow arrow the 2015 terminus location and purple dots the snowline in late October 2015. U=unnamed, CH=Chutanjima Glacier and MO=Mogunong Glacier: which did not retreat significantly and lacks a red arrow.

A recent European Space Agency Sentinel-2A image of southern Tibet, China and Sikkim illustrated three very similar glaciers extending north from the Himalayan divide on the China-India Border. We examine these three glacier in this post. The three glaciers all drain into the Pumqu River basin, which becomes the Arun River. The largest is unnamed the two easternmost are Chutanjima and Mogunong Glacier.The glaciers all have similar top elevations of 6100 -6200 m and terminus elevations of 5260-5280 m. All three are summer accumulation type glaciers with most of the snow accumulating during the summer monsoon, though this is also the dominant melt period on the lower glacier. Wang et al (2015) examined moraine dammed glacier lakes in Tibet and those that posed a hazard, none of the three here were identified as hazardous. The number of glacier lakes in the Pumqu Basin has increased from 199 to 254 since the 1970’s with less than 10% deemed dangerous, but that still leaves a substantial and growing number (Che et al, 2014). Here we compare Landsat images from 1988, 1992 and 2015 to identify their response to climate change. The second Chinese Glacier inventory (Wei et al. 2014) indicated a 21% loss in glacier area in this region from 1970 to 2009.The pattern of retreat and lake expansion is quite common as is evidenced by other area glaciers, such as Gelhaipuco, Thong Wuk, Baillang Glacier and Longbashaba Glacier.

In the 1988 image all three glaciers terminate at the southern end of a proglacial lake with seasonal lake ice cover, red arrows. In 1991 the lakes are ice free and have some icebergs in them. By 2015 the retreat has been 500 m for the easternmost glacier, 400 m for Chutanjima Glacier and 100 m at most for Mogunong Glacier. Each glacier has remained extensively crevassed to the terminus indicating they remain vigorous. The retreat is greatest for the two ending in expanding lakes. Mogunong Glacier appears to be near the upper limit of the lake, and is not calving, which likely led to less retreat. An icefall is apparent 700 m from the front of Mogunong Glacier. The width of the glacier below this point has diminished considerably from 1988 to 2015, though retreat has been minor, indicating a negative mass balance. There is an icefall 1 km from the icefront of Chutanjima, indicating the maximum length the lake would reach.

The Sentinel image indicates an important characteristic and trend in the region. This is an early February image and the snowline is quite high on the glacier in the midst of winter. The snowline is at 5850-5900 m nearly the same elevation as in late October of 2015 seen above. This illustrates the lack of winter accumulation that occurs on these summer accumulation glaciers. It also indicates a trend toward ablation processes remaining active, though limited from November-February. The lack of snowcover on the lower glaciers as the melt season begins hastens ablation zone thinning, mass balance loss and retreat.

Europenan Space Agency, Sentinel-2A image from 1 February 2016. Orange arrow indicates icefalls and purple dots the snowline.

2014 Google Earth image of the region. Orange arrows indicate icefalls, note the crevassing extending to glacier front.

Harris Glacier Retreat, Kenai Fjords, Alaska

On June 14, 2016May 2, 2024 By mspeltoIn alaska glacier retreat, glacier climate change, Glacier Observations, glaciers salmon

Landsat images of Harris Glacier from 1986 and 2015. The red arrow indicates 1986 terminus location, yellow arrow the 2015 terminus position. The orange arrow indicates a key eastern tributary and the pink arrow a smaller eastern tributary.

Harris Glacier flows from the northwest corner of the Harding Icefield, Alaska and it drains into Skilak Lake. The glaciers that drain east toward are in the Kenai Fjords National Park, which has a monitoring program. Giffen et al (2014) observed the retreat of glaciers in the region. From 1950-2005 all 27 glaciers in the Kenai Icefield region examined are retreating. Giffen et al (2014) observed that Harris Glacier (A Glacier) retreated 469 m from from 1986-2005. Here we examine Landsat imagery from 1986-2015 to illustrate the retreat of this glacier and other upglacier changes. The glacier supplies meltwater to Skilak Lake which is a critical salmon habitat for the Kenai. Chinook Salmon spawn on a section of the Kenai River between Kenai Lake and Skilak Lake. With Skilak Lake being the resulting home for ninety percent of the salmon fry for the Kenai River, and with the most of any nursery in the Cook Inlet area. Escapements of chinook in the Kenai River exceed 50,000 annually in two runs (Heard et al 2007).

In 1986 the glacier extended to an elevation of 590 m, on the east side of the glacier there were two smaller tributaries reaching the glacier at the orange and pink arrow. By 2015 the terminus had retreated 600 m from 1986. The eastern tributary at the pink arrow had detached from the main glacier. The tributary at the orange arrow still reaches the main glacier, but the blue ice extent after joining the glacier has diminished significantly. Below is a closeup of the terminus from 1996 and 2015 illustrating a 225 m retreat and associated thinning. It is also interesting to note the prominent ash layer has shifted little. This suggests the terminus area is relatively stagnant. There is no active crevassing in the lower 1 km suggesting retreat will be ongoing. In 1989 the snowline is at 975 m whereas in 2014 the snowline is at 1125 m. This higher snowline is too high to maintain the glacier. The snowline in 2015 was again above 1100 m, though it is lower in the mid-August image at 1050 m. The retreat of this glacier is less than neighboring glaciers such as Grewingk, Pederson and Bear Glacier that have calving termini.

Landsat images from 1989 and 2014, with the snowline indicated by purple dots.

Terminus of Harris Glacier in Google Earth images from 1996 and 2015. Margin with purple dot, purple arrow indicates 1996 terminus lcoation, with a 225 m retreat by 2015. Note the prominent ash layer

Tingmiarmit Glacier Retreat Separates Tributaries, South East Greenland

On May 30, 2016May 2, 2024 By mspeltoIn glacier climate change, Glacier Observations, Greenland glacier retreat

Tingmiarmit Glacier comparison in 1999 and 2015 Landsat images indicating the separation of tributaries at the terminus. The red arrows indicate the 1999 terminus and the yellow arrows the 2015 terminus location. Point A is peninsula where the tributaries joined, and Point B is a nunatak just upglacier from the 2015 terminus.

Tingmiarmit Glacier (Timmiarmiit also) ends in the Tingmiarmit Kangertivat Fjord in southeast Greenland. The glacier is just south of Heimdal Glacier and is noted by Rignot et al (2012) as having a velocity of 1.4 to 3 km/year. Moon et al (2012) note that most glaciers in SE Greenland experienced a significant velocity increase after 2000. In 1999 the glacier terminus was beyond the junction of two main tributaries, with little variation from 1994. Here we examine 1999-2015 imagery to identify the separation and retreat. The retreat is similar to that of nearby Thrym Glacier, which also had a tributary separation and nearby Puisortoq.

In 1999 the glacier terminates 1 km beyond the junction of the two tributaries, indicated by red arrow on each image. The fjord is 2.2 km wide at this point. The terminus had not changed in 2001 Landsat imagery. By 2010 terminus is now located at the junction of the two glaciers. which still share a single calving front, though the calving front is longer with northern and western facing section. In 2015 retreat has led to complete separation of the western and northern tributary. The western tributary is the main glacier and has retreated 2.4 km and the northern tributary has retreated 2.2 km in the sixteen year period. The retreat of the northern tributary has been slower since 2010. The western tributary now terminates 1.5 km from former junction.The fjord is expanding in width, which suggests the current terminus is not at a stable location. The nunatak marked B is a potential point of stability but not likely as the main arm of the glacier goes south of this location and then the fjord continues to expand. Moon and Joughin (2008) observed an ice sheet tidewater glacier retreat rate increase from 2000-2006, coinciding with an increase here. Howat and Eddy (2010) noted a mean change for this region of -107 m per year. Tingmiarmit Glacier’s rate of retreat was slightly higher at 120 m/year for the 1999-2010 period and . Polar Portal continues to expand the number of glaciers with updated terminus positions from satellite imagery with 20 presently.

Mountain Photographer Jack Brauer captured an excellent image of the terminus area in late August, particularly given it was out a commercial airliner window. This image illustrates the steeper slopes and much smaller contribution of the tributaries to the right (east) of Point A and B. The image also indicates that Point B is likely not a significant pinning point to stabilize the terminus. The map below from the Greenland Geological Data viewer indicates the change with the tributaries now disconnected.

Image from Jack Brauer, looking northwest toward Tingmiarmit.

Greenland Geological Data, from the Geological Survey of Denmark and Greenland.

2001 Landsat image

2010 Landsat image, purple dots indicate ice front.

Eagle Glacier, Alaska Retreat Losing a Wing

On May 27, 2016May 2, 2024 By mspeltoIn alaska glacier retreat, glacier climate change, Glacier Observations

Above is a paired Landsat image from 1984 left and 2013 right indicating the 1100 m retreat during this period of Eagle Glacier.

My first visit to the Eagle Glacier was in 1982 with the, ongoing and important, Juneau Icefield Research Program, that summer I just skied on the glacier. In 1984 we put a test pit at 5000 feet near the crest of the Eagle Glacier to assess the snowpack depth. This was in late July and the snowpack depth both years was 4.3 meters, checking this depth in nearby crevasses yielded a range from 4-4.5 meters.In 1984 the snowline at the end of the summer melt season in early September was at 1050 meters.The equilibrium line altitude (ELA) which marks the boundary between the accumulation and the ablation zone each year. On Eagle Glacier to be in equilibrium the glacier needs to have an ELA of 1025 meters. In the image below the glacier is outlined in green, the snowpit location is indicated by a star and the snowline that is needed for the glacier to be in equilibrium at 1025 meters is indicated. The number of years where the ELA is well above 1050 meters dominate since 2002, all but two years see chart below, leading to mass loss, thinning and glacier retreat. This follows the pattern of Lemon Creek Glacier that is monitored directly for mass balance, which has lost 26 meters of thickness on average since 1953.The more rapid retreat follows the pattern of more negative balances experienced by the glaciers of the Juneau Icefield (Pelto et al. 2013). The high snowlines have left the western most tributary with no retained snowpack in 2013, 2014 and 2015, yellow arrow in the 2014 and 2015 Landsat image. This will lead to the rapid downwasting of this tributary.

Eagle Glacier has experienced a significant and sustained retreat since 1948 when it terminated near the northern end of a small lake. By 1982 when I first saw the glacier and when it was mapped again by the USGS the glacier had retreated to the north end of a second and new1 kilometer long lake. In the image below the red line is the 1948 terminus, magenta line the 1982 terminus, green line 2005 terminus and orange line the 2011 terminus. From 1984 to the 2005 image the glacier retreated 550 meters, 25 meters/year. From 2005-2015 retreat increased to 60 meters/year. Going back to the 1948 map the terminus in 2011 is located where the ice was 150-175 m thick in 1948. The high snowlines in 2014 and 2015 along with extended melt season continued the rapid retreat. Total retreat from 1984-2015 is now 1200 m. The retreat hear is less rapid than on nearby Gilkey Glacier or Antler Glacier, but the upglacier downwasting is more severe than at Gilkey Glacier.