North Cascade Glacier Climate Project Observations 2020, 37th Field Season

The North Cascade Glacier Climate Project 2020 field season was our 37th consecutive year of glacier observations.  The field team consisted of Cal Waichler, Mariama Dryak, Jill Pelto and Mauri Pelto.  Each team member has studied glaciers on more than one continent and is passionate about science communicatio, using either art, videography or writing.

Mauri Pelto, Jill Pelto, Cal Waichler and Mariama Dryak from left to right on Easton Glacier the 2020 field team (Jill Pelto Photograph).

At Columbia Glacier the field team  was joined by Michelle Tanz a Wlderness Stewardship Fellow for the National Forest Service.  The initial observation was that the 2 km bushwhack around Blanca Lake has gotten much brushier as the alpine meadow becomes more sub-alpine. Columbia Glacier is a low elevation avalanche fed glacier that developed a new lake at its terminus a decade ago that continues to expand.  The east side of the glacier has been thinning much faster than the west side altering the very shape of the glacier.  Observed snowpack in 2020 was below average except for on the slopes of the main west side avalanche fans. The upper basin at 1550-1650 m averaged 2.2 m of snowpack at the 70 probing locations, which is 70% of normal.  This snowpack will not survive the melt season. Terminus retreat has been 217 m since our first observation in 1984.

Lower Curtis Glacier is fed by avalanches from the slopes of Mt. Shuskan.  We were joined in the field by Tom Hammond for the 17th consecutive year and artist Claire Giordano.  There was a similar pattern to Columbia Glacier in that snowpack across most of the glacier was below average, while the primary avalanche fan on the east side had above average snowpack.  The avalanche fans on the central headwall of the glacier fed from the Upper Curtis Glacier continue to thin rapdily, as avalanching has declined.  The terminus slope which had been a daunting 42 degrees in 2015 is now 34 degrees. For the sixteenth consecutive year we had at least one artist in the field, below are field sketches from Cal Waichler and Jill Pelto and a painting from Claire Giordano.  We will be combining the science findings and art in forthcoming articles.

Claire Giordano working on painting of Lower Curits Glacier and Mt. Shusksan (Mariama Dryak Photograph).

Jill Pelto completes sketch, while sitting on ice chunk, of Easton Glacier icefall (Mariama Dryak Photograph).

Cal Waichler annotated story board style sketches both capture and explain the scene at Columbia Glacier (Mariama Dryak Photograph).

Rainbow Glacier has a terminus that is largely buried by avalanches, but is now is close to detaching from the main valley glacier.  Snowpack at 1700 m averaged 2.4 m which is 75% of average. The saddle with Mazama glacier at 2000-2100 m averaged 3.9 m, which is 85% of normal. Subglacial bedrock knobs continue to become more prominent in expanding crevassing above and slope below the slope change, as the glacier thins.

Sholes Glacier had the highest percentage of surface blue ice of the glaciers observed.  Snowpack had been reduced from at a rate of 8 cm/day during the first week of August, a relatively warm period. A snow cave at the terminus could be entered from a terminus crevasse that was 50 m long, 10 m wide and 2-5 m high.  This is indicative of a relatively stagnant rapidly retreating terminus. From 2014-2020 the glacier has retreated m, which is equivalent to the retreat from 1990-2014.

On Easton Glacier the terminus slope was the gentlest we had seen in our 31 years of consecutive observations.  The terminus has retreated 430 m in this period. The significant thinning in the last few years had both reduced crevassing in the lowest icefall, but had reduced crevasse depth.  Jill Pelto has been observing the crevasses depth in all the open crevasses in this icefall over the last decade.  The biggest change has been from 2018-2020 with average depth being reduced by 40%. Snowpack on the bench at 2000 m averaged 2.4 m at the 45 observation sites, which is 75% of normal.  The snowpack remained below normal at 2200 m, before a sharp increase to above normal snowpack averageing 5.1 m in 14 crevasse observations at ~2500 m. At this same elevation retained snowpack, now firn from previous years averaged 2.25 m. Based on the storm stratigraphy the big difference seemed to be the result of an atmospheric river precipitation event of 12+ cm from 1/31-2/2, that led to a snow depth decline and snow water equivalent decline at the Middle Fork Nooksack Snotel at 1550 m, while above 2300 m this all fell as snow.  The freezing levels were above 2000 m for much of the event.  The better high elevation snowpack will help Easton Glacier’s mass balance in 2020.

Easton Camp from adjacent to 1990 terminus position (Jill Pelto Photograph).

Crevasse stratigraphy at 2500 m on Easton Glacier indicates an average of 5.1 m of 2020 snowpack in crevasses and 2.25 m for previous annual layers from the 2016-2019 period (Mauri Pelto and Jill Pelto Photographs)

North Cascade Glacier Climate Project-Media Links

Circle of  Blue- Disastrous year for North Cascade Glaciers heralds global decline.

National Observer-Climate Change Melts Glaciers puts Salmon at Risk in Washington State

NASA Landsat-Landsat, Art and a Glacier’s Perspective

NASA Landsat-Meet Mauri Pelto, Glaciologist

NASA Earth Observatory-Snow drought on Mount Baker

NOAA Climate-Author focus: Father and daughter talk about their connection to climate, the wilderness of the North Cascades, and each other

NOAA Climate- 2015 State of the Climate: Mountain Glaciers


Toronto Star-Extinction stalks Us West’s great glaciers.

Seattle Times-Watching ice melt for 33 years, scientist finds glaciers are dying at anything but a glacial pace

Science Alert-The Largest Iceberg in Decades Broke Free From a North American Glacier – And No One Noticed

Seattle Times-Disastrous’: Low snow, heat eat away at Northwest glaciers

Chicago Daily -Herald-Northwest glaciers melting, disappearing

Seattle Times-Ice worms’ survival secrets could help humans

Yes MagazineThreat of Salmon Extinction Turns Small Tribe Into Climate Researchers

Washington Post-The nation’s most dangerous snow pile, that even summer can’t melt

WTA-Vanishing glaciers

Mountaineers-Observable Differences: Recession of North Cascade glaciers

Wenatchee World-Lyman Glacier is slowly disappearing

Northwest Mountaineering Journal-Our Vanishing glaciers

Bellingham Herald-Scientists, Nooksack tribe study shrinking Mount Baker glacier

Wilderness Society-Goodbye to glaciers in Washington’s North Cascades?

Rockhead Science-Mauri Pelto Disappearing Glaciers

Recent Climate Change Impacts on Mountain Glaciers-Mauri Pelto

Book Description:

Recent Climate Change Impacts on Mountain Glaciers-Mauri Peltocover

Glaciers are considered a key and an iconic indicator of climate change. The World Glacier Monitoring Service has noted that global alpine balance has been negative for 35 consecutive years. This highlights the dire future that alpine glaciers face.

The goal of this volume is to tell the story, glacier by glacier, of response to climate change from 1984-2015. Of the 165 glaciers examined in 10 different alpine regions, 162 have retreated significantly. It is evident that the changes are significant, not happening at a “glacial” pace, and are profoundly affecting alpine regions. There is a consistent result that reverberates from mountain range to mountain range, which emphasizes that although regional glacier and climate feedbacks differ, global changes are driving the response. This book considers ten different glaciated regions around the individual glaciers, and offers a different tune to the same chorus of glacier volume loss in the face of climate change. Below are some sample image pairs all Landsat images from the book.  The red arrow indicates the earlier terminus, yellow arrow later terminus position and purple arrows upglacier thinning.

I continue to post two blogs a week on glaciers at

Moving to AGU Blogosphere

As of today this blog is shifting to the AGU Blogosphere.  The blog has the same name and will have the same approach with two blogs a week on a the response of glaciers to climate change, one glacier at a time.  If you have been a follower of this blog, please follow there.  Note all the posts have been migrated there too.

Thanks for the continued support and interest.


Mauri Pelto

Field Observations on Lower Curtis Glacier

This is a visual introduction to our 31 years of work on Lower Curtis Glacier complimented with Google Earth imagery to illustrate the changes.  Each year since 1984 this glacier has received an annual checkup from us, North Cascade Glacier Climate Project.  The mass balance and retreat of this glacier is reported to the World Glacier Monitoring Service.  Many nights have been spent camped below this glacier. Unfortunately in the last seven years we have had mostly wet weather at this site, that hopefully will not be repeated this coming summer. 

Zongo Glacier Retreat, Bolivia 1994-2014.

Zongo Glacier, Bolivia extends 2.9 km down the south side of Huayna Potosi from 6000 m to 4900 m. Zongo Glacier is a small valley glacier located 30 km north-east of La Paz, and its runoff is directed to an important hydraulic power station which supplies La Paz. Note Laguna Milluni in foreground of the first image. The dam is visible as is the power station to the right and below the lake. The glacier has considerable snowcover on its upper section and crevassing. This indicates a persistent accumulation zone. In 1991 a glaciological research program was established on Zongo Glacier to monitor mass balance, understand its hydrology and energy balance. The long term director of this research Bernard Francou has been called the glacier guardian. The cumlative mass balance of the glacier from 1991-2013 has been -6.5 m water equivalent. The typical Alpine glaciers undergoes a long accumulation period in winter and a short ablation season in summer. The glaciers of the tropical Andes experience snow accumulation during the wet season, austral summer on their upper regions and maximum ablation during the same season low on the glacier. In the dry season winter there is a period of low ablation over the whole glacier. Mean annual air temperature at the long term snowline at 5250 m is -1.5 °C. Mean precipitation is about 0.9 m/year. zongo laguna
Google Earth image-Huayna Potosi and Zongo Glacier

Since 1991 the glacier has lost more than 7 m of thickness and has retreated significantly. The mass balance loss has been most pronounced during El Nino periods. La Nina’s are associated with positive or only slightly negative mass balance. Here we examine Landsat imagery and Google Earth imagery form 1994 to 2014.

In 1994 there is no lake at the terminus of the glacier, red arrow. By 2004 the Google Earth image indicates the glacier terminating along the northeast shore of the lake, a 90 m retreat in a decade. By 2008 the glacier no longer reaches the edge of the lake, but the front is still crevassed. In 2014 the glacier terminates 100 meters from the lake. Total retreat during the 20 year period is 220 m. The current terminus in 2014 is dirtier and less crevassed than in 2004, and less crevassed than in 2008. The lower 200 m of the glacier is thin, narrow and lacks active crevassing. This relatively stagnant area will melt away in the next decade.

Zongo Glacier continues to have an accumulation zone, a necessary essential for glacier survival, and unlike the nearby Chacaltaya Glacier which disappeared in 2009, it will exist for sometime. The Chacaltaya Glacier is a small glacier, like 80% of the glaciers in this region of the Cordillera Real, and its disappearance puts more pressure on the water resources provided by the larger remaining glaciers such as Zongo Glacier. Rabatel et al (2013) note the striking rise in the freezing levels in the region due both to higher temperatures and more convective activity that is a particular threat to glacier survival.

zongo ls 1994
1994 Landsat image

zongo 2004
2004 Google Earth image

zongo 2008
2008 Google earth image

zongo 2014
2014 Google Earth image

zongo ls 2014
2014 Landsat image

Mahsa Icefield Retreat and Separation, Baranof Island, Alaska

The Mahsa Icefield is at the headwaters of Takatz Creek.  This is a small glacier, not an actual icefield.  Five kilometers to the west is another small unnamed glacier at the headwaters of Sawmill Creek.  Here we focus on changes in the two glacier using Landsat images from 1986 to 2014.mahsa icefield ge

Google Earth image

In 1986 the Mahsa Icefield is a contiguous glacier that extended 5 km from east to west, red arrow indicates  the mid-section of the icefield.  A separate glacier in Sawmill Creek, yellow arrows, was 2.1 km long and has no lake at its terminus.  In 1997 the Mahsa Icefield has separated into an east and west half, at the red arrow, and has lost all of its snowcover.  The glacier in Sawmill Creek is still a single ice mass, but has lost all of its snowcover, which happened in 1998, 2003 and 2004. In 2014 the Mahsa Icefield’s east and west half are separated by 300 m, red arrow.  There is very little snowcover remaining despite there is a month left in the melt season.  At the headwaters of Sawmill Creek a lake has formed as the glacier has retreated, the lake is 600 m long in 2014.  The glacier has also separated into a small upper and lower section.  This glacier has lost half of its area since 1986.  The retreat of these glaciers on Baranof Island is similar to the retreat of nearby Carbon Lake Glacier,Lemon Creek Glacier, and Sinclair Glacier. Lemon Creek Glacier has lost more than 25 m of glacier thickness during the 1953-2014 period when its mass balance has been observed by the Juneau Icefield Research Program, and has retreated more than 1 km (Pelto et al, 2014).

mahsa icefield 1986

Landsat image 1986

mahsa icefield 1997

Landsat Image 1997

mahsa icefield 2014

Landsat image 2014


Carbon Lake Glacier Retreat, Alaska

On Baranof Island in southeast Alaska there are a pair of unnamed glaciers at the headwaters of the Carbon Lake watershed, that then drains into Chatham Strait.  Here we examine changes in these glacier from 1986 to 2014 using Landsat imagery.  The blue arrow indicates the northern glacier terminus and the yellow arrow the southern glacier terminus region.

carbon lake ge

In 1986 the southern glacier terminus, yellow arrow consisted of three main tributaries combining to form a low sloped terminus region.  The northern glacier had a single terminus.  By 1997 a lake has formed at the southern glacier, which now has two separate termini, the red arrow indicates a new terminus area and the pink arrow the eastern portion of this glacier.  The northern glacier, blue arrow, is retreating but still joined.  By 2014 the southern glacier has separated into three parts.  There is a terminus at the red arrow, this represents a 900 m retreat since 1986.  This portion of the glacier has further separated since 1997 into two parts.  The eastern glacier, pink arrow has retreated 700 m since 1986.  The new alpine lake is 600 m long.  The northern glacier, blue arrow, has separated into two main termini and the glacier has retreated 200 m.   The retreat of these glaciers paralells the observed losses of other smaller glacier in the region most notably Lemon Creek Glacier, which is a World Glacier Monitoring Service reference glacier, 30 km west on the edge of the Juneau Icefield.  Another nearby example is Sinclair Glacier.  Lemon Creek Glacier has lost more than 25 m of glacier thickness during the 1953-2014 period when its mass balance has been observed by the Juneau Icefield Research Program, and has retreated more than 1 km.

carbon lake 1986

1986 Landsat image Carbon Lake Glaciers

carbon lake 1997

1997 Landsat image Carbon Lake Glaciers

carbon lake 2014

2014 Landsat image of Carbon Glacier



Chickamin Glacier Retreat, North Cascade Range, Washington

Chickamin Glacier covers the north slope of Sinister Peak in the North Cascade Range of Washington.  The glacier has a valley tongue that descends to an outwash plain.  Here we examine retreat of the glacier from 1979 to 2012. The glacier had advanced from 1955-1975, before commencing retreat.

Chickamin Glacier (Tom Hammond)

chickamin map

USGS Map of Chickamin Glacier

In 1979 the glacier terminus was at the pink arrow, several hundred meters beyond a prominent buttress, red arrow, where the glacier turns west.  The lowest icefall is indicated by a green arrow. In 1991 the glacier has retreated from the pink arrow, but still is turning the corner beyond the buttress.  The lower icefall is still extensively crevassed.  By 1998 in a Google Earth image the terminus is outlined with yellow dots and has retreated 230 m from the 1979 position.  The lower icefall is still crevassed.  By 2005 in a photograph from Tom Hammond (North Cascades Conservation Council), the glacier has retreated to the buttress. in a 2006 Google Earth image the terminus position is indicated by yellow dots, with a retreat of 50 m since 1998.  The lower portion of the glacier has limited crevassing.  In the 2012 image the glacier terminus no longer reaches the buttress and has retreated 360 m since 1979. We observed exceptional ablation conditions in the North Cascades in 2013 and 2014, which combined with exceptionally low snowpack in 2015 will lead to a continued significant retreat of this glacier.  The crevassing in the lowest icefall has declined and is now superficial. All 47 glaciers observed by the North Cascade Glacier Climate Project have been retreating and four have disappeared (Pelto, 2011). This glacier is similar in size and retreat to Boston Glacier and Honeycomb Glacier.


Chickamin Glacier 1979 (Austin Post)chickamin glacier1991

1991 Chickamin Glacierchickamin 1998 geterminus

1998 Google Earth image


2005 Chickamin Glacier (Tom Hammond)chickamin 2006 geterminus

2006 Google Earth imagechickamin 2012 geterminus

2012 Google Earth Image

Eiriksjökull Reeat, Iceland

Eiriksjökull  is an ice cap just west of Langjökull In central Iceland.  Here we examine its main western outlet the Braekur using Landsat imagery from 1989 to 2014.  The Icelandic Glaciological Society website on terminus variations is the source of the map for the glacier. The IGS program monitors 50 glaciers, all of them are currently retreating.  Eiriksjökull ,  is not one that is in this monitoring program. eiriksjokull map

In 1989 the Braekur outlet flowed over the edge of a lava cliff at the red arrow.  The glacier terminated on the bench between the upper and lower cliff.  In 1994 the glacier still extended  to the edge of the cliff.  By 2010 the Google Earth images indicates a retreat from the edge of the cliff.  In 2014 the glacier has receded 200 m from the edge of the cliff and 300 m from is 1989 position and terminates at the yellow arrow. The high snowlines in recent years will lead to continued retreat. The retreat and area loss of Eiriksjökull is less than on nearby Norðurjökull a primary outlet of Langjökull or on Porisjokull a small ice cap just south of Langjökull.

eiriksjokull 1989

1989 Landsat image

eiriksjokull 1994

1994 Landsat image

eiriksjokull 2010

2010 Google Earth image

eiriksjokull 2014

2014 Landsat image

Weddel Glacier Thinning-Retreat, South Georgia Island

Weddel Glacier is on the southeast coast of South Georgia Island.  It terminates in Beaufoy Cove just north of Gold Harbor.The change in glacier terminus position has been documented by Alison Cook at British Antarctic Survey in a BAS retreat map.  In 1958 it reached within 400 m of the coast at the outlet of Beaufoy Cove. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980s. For Weddel Glacier the retreat was rapid from 1960 to 1974 and was slow from 1992-2003.  Here we examine Landsat imagery from 1989 to 2015 to visualize and update this change.
bertrab ge
Google Earth Image

weddell-bertrab map
BAS map of glacier terminus position

In 1989 the glacier terminates near the tip of a peninsula, red arrow in each image. The calving front extends southeast, orange dots. At the yellow arrow the glacier fills a small side valley adjacent to the main glacier. At the purple arrow is a small extension of the main icefall flowing down the bedrock step.
In 2002 there is only minor retreat at the red and yellow arrow, but thinning has led to the small extension of the main icefall being almost cutoff by bedrock. By 2015 the glacier has retreated 200-300 meters from the 1989 position and the main terminus is narrower. At the yellow arrow the side valley no longer has ice. At the purple arrow this is just bedrock now, there is no glacier extension flowing down the bedrock step. A close up the icefall in a 2009 Google Earth image indicates both the extensive crevassing but also the lack of glacier ice at the purple arrow, where an extension of the icefall formerly flowed. A Google Earth closeup of the terminus indicates that only a small section is still in contact with Beaufoy Cove in 2009, with land exposed at the orange arrows. This glacier is almost not tidewater and has terminated in shallow water since 1989, which helps explain a slower rate of retreat. The glacier has thinned more rapidly than it has retreated in the last 25 years. The retreat rate is less than nearby Bertrab Glacier, Konig Glacier and Neumayer Glacier on the same coast of South Georgia.

weddel glacier 1989

Landsat Image 1989

weddell glacier 2002

Landsat image 2002

weddel glacier 2015
Landsat image 2015

weddel icefall
Google Earth icefall image
weddel terminus
Google Earth 2009 image

Bertrab Glacier Retreat, South Georgia Island

Bertrab Glacier is on the east coast of South Georgia Island.  The change in glacier terminus position has been documented by Alison Cook at British Antarctic Survey in a BAS retreat map.  In 1958 it reached the coast in Gold Harbor. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980s. For Bertrab Glacier the retreat was minimal from 1958 to 1989. Since 1989 a whole new embayment has opened.  Here we examine Landsat imagery from 1989 to 2015 to visualize and update this change.

weddell-bertrab map

BAS Glacier Front map 1958-2007.

bertrab ge

Google Earth image

In 1989 the southern arm of the glacier extends to the shoreline of the barrier beach system in Gold harbor, Red arrow. The northern arm extends around to the edge of a very green region, suggesting well developed vegetation, hence no real retreat for sometime.  By 2002 a lake has formed at the northern arm terminus and it has retreated 400 m.  The southern arm has retreated across a new embayment ending near the yellow arrow, though the exact position is obscured by cloud.  In 2011 the southern terminus has retreated up a slope from the edge of the embayment, yellow arrow.  In 2015 there are no longer two arms to the glacier.  The glacier terminates near the edge of the new embayment. The retreat is 700 m on the northern arm and 1000 m for the southern end since 1989.  The glacier no longer reaches the water limiting calving.  The glacier also ends on moderate slope.  This should lead to a reduced retreat in the near future.  The 2015 picture is from Jan.15, so there is still two months left in the melt season. The retreat is similar to that of Ross Hindle Glacier , Konig Glacier and Neumayer Glacier on the same coast of South Georgia, and faster than for neighboring Weddel Glacier.  Like on Stephenson Glacier, Heard Island the new embayment does offer new potential habitat for penguins and seals.

bertrab glacier 1989

1989 Landsat image
bertrab glacier 2002

2002 Landsat image

bertrab glacier 2011

2011 Landsat image

bertrab glacier 2015

2015 landsat image