Snow cover extent on Mount Shasta glacier as the melt season ends in 2024. Oct. 15, 2024 Sentinel image, red dots indicate outline of snowcover areas ~25% of glacier area.
In 2021 and 2022 winters of below average snowfall , 4.50 m and 3.61 m at Snow Bowl, were followed by summers of persistent heat and several notable heat waves that left the glaciers of Mount Shasta nearly bare of snowcover, the resulting rapid volume loss and fragmentation of the glaciers was noted in detailed reports (Patel, 2021; Pelto, 2022). In 2021 less than 5% of the glaciers retained snowcover, and in 2022 less than 10% was retained.
In 2023 and 2024 a pair of winters with much above normal snowfall, 8.51 m and 8.43 m inches at Snow Bowl blanketed the mountain. How much of this snow has been retained by the glaciers as the 2024 melt season concludes.
Snow cover extent in September 2021 is less than 5% on Mount Shasta glaciers in this Sentinel image.
The summer of 2023 featured persisten warmth that led to ….In 2024 the melt season was again warm with the mean departure being 1.5-2.0 C in the Mount Shasta area. Regional Climate Center ACIS maps of the temperature anomaly for June-August provide a comparison of summer temperature for 2021-2024. Examining the remaining snowcover extent on Oct. 15, 2024 illustrates that
Summer temperature anomaly (in oF), for 2021-2024 for California. Each summer the departure has exceeded 1 C in the Mount Shasta region.ACIS maps
For Cascade range glaciers to maintain equilibrium they need 60% snowcover at the end of the melt season. Examining the remaining snowcover extent on Oct. 15, 2024 illustrates that the three primary glaciers Bolam, Hotlum and Whitney have 25% snowcover remaining. This indicates signficant loss of volume in 2024, though less than 2021 or 2022. This will drive continued thinning, retreat and loss of glaciers.
Snowcover extent on Aug. 30, 2022 on Munt Shasta Glaciers. Yellow arrows indicate that less than 10% of the glaciers are snowcovered.
Serac on Easton Glacier at 2400 m indicating retained snowpack from previous years.
Climate Conditions Summary
The winter season of 2023/24 yielded a low snowpack across the North Cascades. Snowpack at six longer Snotel stations was 0.63 m w.e on April 1, vs. a 1984-2024 average of 1.02 m. This was the third lowest snowpack of this period, with 2005 and 2015 being lower. The melt season in May and June was cool, helping extend the low snowpack at elevations above 1500 m. July rivaled 2015 for the warmest of the last 50 years, quickly melting back the snowpack by the start of August. The end of the melt season was fairly typical with several new snowfalls and periods of heat. The main melt season for the glaciers is June-September and this year the average temperature was 18.3 C, which is 1.3 C above the long term mean. This was the fourth year in a row above 18 C and thus the fourth consecutive year of large glacier mass balance losses. The cumulative impact is glacier recession, thinning, loss of a number of glacier and overall steeper/dirtier ice. We conducted detailed field work on eight glaciers.
Probing snow pack depth on Lower Curtis Glacier. The 12 foot segmented steel probe cannot penetrate the icy surface from the previous summer.
Glacier Mass Balance
Annual mass balance is the difference between the mass of snow and ice accumulation on the glacier and the ablation of snow and ice on the glacier during a year. The data is reported in the average change across the glacier in water equivalent thickness. In 2024 we again utilized probing snow depth with a 12 foot long segmented steel probe (520 measurements), annual layer thickness measurement in vertically walled crevasses (140 measurements), and mapping snow line position in the field. To assess ablation we used snow line migration in satellite imagery and ablation stakes drilled into the glacier. The mass balance at the snowline is 0 m w.e., and as it transects areas of known snow depth that identifies ablation rate.
Ben Pelto deploying his ice augur to emplace ablaiton stakes on Sholes Glacier, Katie Hovind and Mauri Pelto assisting.Jill and Mauri Pelto in front of Columbia Glacier that has retreated forming a new lake. Avalanche accumulation on west side only snowcover retained by end of summer.
All eight glaciers had a negative balance exceeding 1.3 m w.e., with an average of -2.09 m w.e., this is equivalent to at ~2.25 m of glacier thinning. The loss during the last four years is unprecedented with 8 m of average thickness lost from 2021-2024. This is greater than the entire decade of loss for 184-1993, 1994-2003 or 2004-2013. The acceleration of loss continues even as the glaciers lose their highest melting terminus regions. This is an indication that none of the glaciers are approaching equilibrium. The cumulative mean mass balance loss has been -28.89 m w.e., ~33 m in thickness. This represents the loss of ~40% of volume of the glaciers we have observed, 1% loss per year overall but over 2% per year in the last decade.
Annual mass balance time series for the eight glaciers we monitor and the USGS monitored South Cascade Glacier. In 2024 Columbia=-2.34, Daniels=-2.70, Easton=-1.74, Ice Worm=-2.40, Lower Curtis=-1.82, Lynch=-2.35, Rainbow=-1.38, Sholes=-2.35.
The deglaciated area exposed by the retreat over the last four decades is substantial and is most visible below Easton Glacier. The retreat of 620 m since 1990, has included a retreat of over 100 m in the last two years. The thinning of this glacier along with neighboring Squak and Deming have led to emergence of bedrock areas high on the glacier as well.
Deglaciated area below Easton Glacier from the 1990 advance moraine to 2024.Bedrock areas that are emerging and expanding above 2100 m on the upper portions of Deming-Easton and Squak Glacier. Only one of these (upper right) existed before 2010.
Glacier Crevasses
We have been assessing the depth and distribution of crevasses on several glaciers annually since 2013. We have noted a decline in the number of crevasses in specific icefall regions, such as on Lower Curtis, Rainbow and Easton Glacier. The depth also decline rapidly with glacial thinning during the last decade. In the main icefall on Easton Glacier in 2024 at 2300 m were the deepest crevasses we found at ~30 m. Below is Jill Pelto measuring crevasse depth using a camline.
Glaciers Lost
There are 31 active glaciers across the North Cascades that we observed since the 1980s that have now disappeared. The list below indicates the year they were lost, the area of the glaciers in the GLIMS inventory for initial area (1958-1984), 2015 area, and the area of the former glacier in 2022/24. This is not a complete list of glaciers lost in the North Cascade Range. The rate of loss is clearly accelerating.
When a glacier’s volume becomes too limited to generate motion, a combination of thickness below ~15-25 m, and area less than 0.02-0.05 km2, it is no longer a glacier.
North Cascade glaciers that we observed as glaciers in the 1980s that are now gone. The first two areas reported come from GLIMS.org inventories, and the last area and year of loss come from our observations.
Glacier Runoff
We directly measured runoff below Sholes Glacier and in the basin of former Ice Worm Glacier. In each continued glacier recession is reduing glacier runoff. The increased rate of melt is, exceeded by the reduced area available for melting. The result is declining summer streamflow and increased late summer stream temperatures.
The 2024 field season was our 41st, from the glaciers perspective it was the fourth consecutive year of exceptional mass loss, leading to thinning, retreat and glacier loss.Below are images from the field season and reflections on each from the varied perspectives of our field team and field partners.
Coleman Glacier, Mount Baker at the golden hour as we just finished work.
Jill Pelto: During the field season our typical day involves getting up with the sun and working out on a glacier until early evening. Going to Coleman Glacier on Mt. Baker this year was special because we got to work on it during golden hour, a rare thing to experience. We had the glacier to ourselves, and the nearby big camping area — despite this being a popular destination for ice climbers. This is only my third time in sixteen years working on this glacier, and its significant loss since we last saw it in 2019, when I sat and painted on it, was so apparent. But in spite of that, I was feeling joyful to be there — something about four of us out there on our own taking measurements as the summer sun set was so magical. I was so grateful to be there at that moment and experience this landscape as it is now.
Saddle at top of Rainbow Glacier looking to summit of Kulshan (Mount Baker). Ben, Jill and Mauri Pelto a combined 70+ years of experience on these glaciers.
Mauri Pelto: Climate change has led to increased glacier melting on all of the glaciers we have observed. A combined 70+ years of field experience that Ben, Jill and I have provides a context that is crucial. The increased melt is apparent in the streams flowing across the surface very few meters carrying meltwater to the rivers and then the sea. This summer we saw the beauty of the final stages of decay of a glacier melting away in the ice caves that transected the former Ice Worm Glacier (image below). The cave started at the top of the glacier and continued right to the bottom, by next summer that too will be gone. The colors and atmosphere in the cave were spell binding. The landscape remains beautiful, but is losing the glaciers that are a powerful, beautiful and dynamic part of this landscape.
Katie Hovind: Nestled along Ptarmigan Ridge, overlooking Kulshan’s glacier-flanked slopes, was our longest campsite of the field season. Unzipping my tent to an increasingly familiar skyline four mornings in a row, I found myself developing a relationship with this place. I noticed patterns and changes alike, discovering not just the place but a sense of home in it. We followed transects across the Sholes, probing up and down the glacier; we explored a collapsed ice cave near its terminus, blue ice towering over me, ancient wisdom frozen in the dripping layers I ran my hands along; we took water measurements from the stream it feeds, pausing for a break next to the fresh melt as I sketched the textures of rock and snow and ice. We commuted across it twice to the Rainbow Glacier, a trek familiarizing me with the Sholes’ sweeping slopes and views; and we screwed an ice auger deeper than we could see, dropping stakes 3-4 feet below the surface. 19 days later, I returned to the coordinates of those four stakes, which were now all exposed, one sticking up to just over 3 feet above the surface. Reeling as I walked across the glacier I’d gotten to know, the near-incomprehensible volume of loss I saw. A feeling of belonging is so integral to caring. And then comes the question of how to transmit that connection, to spread to others the same sense of responsibility to protect a place? Being lucky enough to experience even a handful of days taking in just a small degree of the Sholes’ nuances, I felt deeply just how wrong and quick the melt is. But from the outside looking in, without any prior reference points, the severity of the glacier shrinking could be overlooked. Through these comparison photos, I hope to share just a glimpse, beauty and grief and all, of what it means to understand and love a glacier.
Emma Murray: Just a few minutes into our hike from camp to the Easton glacier, Science Director Mauri Pelto pointed out the rock that marked the spot where he put his crampons on in 1990. Looking up the valley, the ice felt SO far away. This glacier has retreated almost 600m in my lifetime already. In response to the melting at each of the six glaciers I visited during my time with the Project, I added paint, pen, and thread to canvas. These flags are both white-flag surrenders to all the melting we cannot stop and blowing-in-the-wind prayers for us all to act in the ways we can. I hope these pieces help people to visualize and feel the difference between where the ice was and where it is now. I think feeling that loss is groundwork for our urgent conversations about climate solutions, which can be uplifting and cool and pragmatic and creative!
Shari Macy: Mauri Pelto, peers into the melting terminus of the Lower Curtis Glacier; located on the southern slopes of Mount Shuksan in the North Cascades of Washington State. As founder of the North Cascade Glacier Climate Project, he has been measuring these shrinking giants since 1984. This image, to me, shows a man and what he dedicated his life to studying. A passion that drove him to spend over 700 nights in tents, camped out next to the glaciers of the North Cascades. These glaciers could use a lot more people like Mauri. Does everyone need to backpack to remote glaciers every summer? No. He already does. However, we could all be a little more dedicated to the health of our planet, our home. Our one and only. Our children’s one and only.
Megan Pelto: To me, Mt. Baker represents the North Cascades. Camping next to its looming presence makes me aware of how impactful it is, its glaciers helping support the ecosystem and the wildlife that surround it. Getting to be present in this wilderness feels like a gift and a chance to both disconnect and reconnect. Everything you have is contained in one little tent and the experience of camping in this landscape is magical. I wanted to capture that with our colorful little tents tucked into grassy hills with Baker above us. I have been able to visit this landscape over the past 10 years, and while the glaciers change each year, many things have remained peacefully the same.
Ben Pelto: Disappearing glaciers remind me of grandparents—I’m saddened by their decline, yet deeply grateful for the time I still have with them. This year, being in the field was especially meaningful, surrounded by an incredible group of people, just experiencing the mountains and soaking it all in. What I find hardest about glaciers vanishing is not just the loss of ice, but the disappearance of their dynamism and beauty from the landscape. These ancient giants bring a sense of magic and power to the mountains, and it breaks my heart to think that my children or grandchildren might never witness them as I have.
Cal Waichler: This season I ask what it means to be a voice for glaciers. How can I transmit my gratitude that I can stand on this earth, breathe glaciers’ breezes, seep in icy blue and alpenglow rose, pop alpine huckleberries in my mouth, and notice the shrinking snow and dissolving ice, while also alerting people to their vulnerabilities? Glaciers are a throughline in my explorations and art. I am so utterly enchanted by them. The awe and creative inspiration they bring to my life is a great gift. As a voice for shrinking glaciers, what stories can I share that will enchant other people with them? What will make us care enough to enact climate change mitigation and adaptation, and vote for climate leaders? Here, a snapshot of those most transient and irreplaceable things.
Most Svalbard glaciers in this Landsat image from 8-8-2024 are snow free. This view is centered on 78 N and 19 E spanning parts of Barentsoya, Edgeøya and Spitsbergen. On Langjokulen (La), Kvitisen (Kv), Bergfonna (Be), Blaisen (Bl) and Storskavlen (St) on Edgeøya snow cover is gone. Bjarmanbreen (Bj), Passfonna (Pa), Hellefonna (He), Sveigbreen (Sv), Nordmannsfonna (No), Isrosa (Is), Kamfonna (Ka), Breitfonna (Br), Rugaasfonna (Ru), Hayesbreen (Hy), Heuglinbreen (Hu) on Spitsbergen all snowcover is lost.There is a small amount of snowcover left in the upper reaches of a few glaciers including Freemanbreen (Fr), Gruvfonna (Gr), Siakbreen (Si), Von Postybreen (VP) and Fimbulisen (Fi).
All the glaciers labelled in the Nathorst Land and Nordenskjold Land region of Svalbard are snow free on 8-11-2024 in this Landsat image. Er=Erdmannbreen, Fr=Fridtjovbreen, Gr=Gronfjorden, Ta=Taviebreen, Ma=Marstranderbreen, Gl=Gleditschfonna in Nordenskjold. HO=Hoegh Omdalbreen, Sn=Snokubreen, Fy=Frysjabreen, In=Instebreen, Ri=Richterbreen, Ri=Ringerbreen, La=Langlibreen, Lo=Loyndebreen, Lu=Lundbreen, Sy=Sysselmannbreen in Nathorst Land.
Warm temperatures across Svalbard in July and early August has resulted in many glaciers losing all of their snowcover. The result will be enhanced and significant thinning of these glaciers. This follows on 2022 which was the warmest summer on record in Svalbard and led to many snow free glaciers (Pelto, 2022). This record was exceeded in summer 2023 (Copernicus Climate Change Service, 2024). Here we look at Landsat images and Sentinel images across several islands from late July and early August illustrating the widespread nature of the extensive glacier snow cover loss.
For ice caps such as Glitnefonna, Langjokulen (La), Kvitisen (Kv), Bergfonna (Be), Blaisen (Bl) and Storskavlen (St), because of their low top elevation and relatively flat slopes their ability to survive is dependent on much of meltwater generated on the higher plateau areas being refreezing within the firn instead of escaping the glacier (Noel et al 2020). In 2020 the snowcover was lost and the firn thickness diminished. In August 2022 the snowcover again was lost and there was little evident firn that could lead to refreezing of meltwater. In August 2024 snowcover loss has again occurred.
For the glaciers of Spitsbergen to maintain .equilibrium requires 50% of the glacier needs to be snowcovered at the end of summer. By early August with a month left of summer melt, the area is below 10% on every glacier noted above. How much more melt will occur. The net result will be extensive mass loss once again (NASA EO, 2024).
Glitnefonna is a 145 km2 ice cap in Gustav Albert Land where snowcover declined from 55% snowcover on 7-22 (purple dots) to 0% snowcover on 8-9-2024 in these Sentinel images. A small area of saturated firn/snow is evident, yellow dots.Glitnefonna is a 145 km2 ice cap in Gustav Albert Land where snowcover declined from 50% snowcover on 7-18 (yewllow dots) to 0% snowcover on 8-9-2024 in these Landsat images.
Change in terminus position of coastal glaciers in the Sewqrd region. On this 2023 Landsat image yellow dots are ther 2023 terminus and red dots the 1986 terminus.
Turn east along the coast from Seward Alaska and you are offshore of the Sargent Icefield, turn west and you are offshore of the Harding Icefield. Each has several large glaciers that were either tidewater or end in lakes separated from the ocean by a narrow coastal zone. Here we compare the response to climate change of seven of these glaciers from 1986-2023.
Change in terminus position of coastal glaciers in the Sewqrd region. On this 1986 Landsat image-yellow dots are ther 2023 terminus and red dots the 1986 terminus.
Travelling south down Resurrection Bay and turning east you enter into Day Harbor, at the head of which is the outlet for Ellsworth Glacier. The glacier terminates in an expanding lake that was 3.5 km long in 1986 and in 2023 is 8 km long. The 4000 m retreat generated some large icebers still in the lake.
Elsworth Glacier retreat from 2016-2020 leading to quick lake expansion in Landsat Images
Travelling east from Day Harbor 15 km brings you into Johnstone Bay. Excelsior Glacier termiates just inland from the coast is a rapidly expanding lake. The lake was 5 km long in 1986, and by 2023 is 10.5 km long, a retreat of 5500 m. The glacier has separated with the Roan Glacier terminus to the east retreating from the lake. The Excelsior Glacier terminus currently is steep and nearing the north end of the lake.
Rapid expansion of Big Johnstone lake due to Excelsior Glacier retreat. Map from 1950, Landsat images 2001 and 2013.
Heading south down Resurection Bay on the western shore is Bear Glacier. From 1950-1986 the glacier retreated 160 m, and by 1980 the terminus was calving small icebergs into an ice-marginal lake that was beginning to develop. As thinning continued, much of the terminus became afloat by 2000. Bruce Molnia, USGS observed that passive calving, characterized by the release of large tabular icebergs from Bear’s low gradient, floating terminus became frequent. Between 2000 and 2007, the terminus retreated about 3.5 km, yielding large icebergs that floated in the lake. The amount of calving has declined from the period of more rapid retreat from 2002-2008. Black et al (2022) reported Bear Glacier retreating 5170 m. losing 17.28 km2 of area from 1984-2021. From 1986 to 2024 the glacier has retreated 6200 m, leading to a lake with an area of km2.
The retreat of Bear Glacier from 1986 to 2024 leading to growth of the lake to 22 km2, in Landsat images.
Continuing around Aialik Peninsula and traveling north into Aialik Bay, along the western shore is Pedersen Glacier. The glacier drops quickly from the plateau of the icefield through a pair of icefalls terminating in a lake at 25 meters above sea level. Giffen et al (2014) observed that Pedersen Glacier retreated slow but steady from 1951-1986 at 706 m (20 m/a) and 434 m (23 m/year) from 1986-2005. Black et al (2022) reported a retreat of 3170 m and loss of 4.25 km2 from 1984-2021. We note a 3500 m retreat from 1986-2023.
Pederse Glacier retreat in Landsat images, leading to rapid lake expasion to 4 km2.
At the head of Aialik Bay is the tidewater Aialik Glacier. This glacier advanced 180 m from 1950-1986.From 1986-2006 the glacier retreated 290 m. Black et al (2022) observed the terminus was stable from 2000-2021 despite ongoing receession of the eastern margin of the glacier.
The Holgate Arm extends off of Aialik Bay on the west shore just south of Pedersen glacier. This tidewater glacier retreated 250 m from 1950-1986. The glacier has had several small periods of advance and retreat since 1986. Black et al (2022) note a period of advance from 2010-2021, the terminus has begun a small retreat from 2021-23 and is now just behind the 1986 position.
Northwestern Glacier is at the head of Northwestern Fjord off of Harris Bay, the next Bay west of Aialik Bay. This tidewater retreated 5200 m from 1950-1986, and an additional 1600 m since 1986. This retreat has led to a separation into two primary arms of the glacier. The rate of retreat has slowed since 2000 and the glaciers tidewater connection is limited, and will likely cease with even further minor retreat.
The Harding and Sargent icefield both have limited accumulation area above 1500 m. This means that they are prone to complete loss with a limited rise in snowline elevation. This is similar to the Juenau Icefield situation, where our research has indicated accelerated losses (APNews).
Grand Plateau Glacier on June 15, 2024 Sentinel image, illustrating 5.5 km retreat from Island (I) where terminus was located in 1984. N illustrates nunatak the glacier terminated 11 km from 1948 terminus. Point A is new island emerging at terminus. The Lake that barely existed in 1948, has more than doubled in size since 1984 to 49 km2.
Grand Plateau Glacier drains southwest from Mount Fairweather in southeast Alaska. The glacier advanced during the Little Ice age to the Alaskan coastline. Early maps from 1908 show no lake at the terminus of the glacier. The 1948 map (below) shows three small distinct lakes at the terminus of the main glacier and a just developing lake at the terminus of the southern distributary terminus (D). The distance from the Nunatak N to the terminus was 11 km in 1948. The lake at D is 400 m wide.
USGS 1948 topographic map of area Illustrating three small disconnected proglacial lakes at the terminus (I).
USGS 1948 topographic map of area Illustrating distribuatry tongue
Grand Plateau Glacier in 1984 Landsat image indicating 1984 terminus at orange arrows, 2013
Landsat images from 1984 indicates the fromation of a single connected proglacial lake with an area of 24 km2. Key reference points in each image are the Nunatak, N, and and Island, I. The retreat from 1984-2013 is evident with the orange arrows indicating the 1984 terminus and pink arrows showing the 2013 terminus location. The distance from the Nunatak to the terminus is 8.5 km in 1984 and 4 km in 2013. On the north shore of the lake the retreat between arrows is 2.7 km from 1984-2013. From the island the glacier retreated 3.3 km from 1984-2013, with the lake expanding to 43 km2. The distributary tongue (D) retreated 2.2 km from 1984-2013. The retreat was driven by higher snowlines in recent years, the snowline had been reported at 1000 m in the 1950’s. Satellite imagery of the last decade indicates snowlines averaging 1500 m, red arrows. The glacier snowline is evident in Landsat imagery in 1984 and 2013 red arrows.
In 2024 the lake area has grown further to 49 km2, as a result of a retreat of 8 km since 1948 and 5.5 km since 1984. Today a second island is emerging at the terminus, Point A. The distributary tongue to the southeast now terminates in a lake that is now 5.2 km long, a 4.8 km retreat since 1948 and 2.6 km since 1984. The combination of higher snowlines and increased calving into the terminus lake will continue to lead to retreat of this still mighty river of ice. This retreat parallels that of nearby Alsek Glacier and Yakutat Glacier. The rapid growth of the three lakes since 1984 when I visited them is amazing.
La Perouse Glacier in 2018 and 2023 Landsat images indicating the six developing proglacial lakes (1-6). The lakes in 2023 have a combined area of 1.3 km2. Debris cover has expanded notably at Points D.
La Perouse Glacier flows from the Fairweather Range to the Pacific Coast. The glacier advanced to the coast in the mid-late 19th century and has remained tidewater on the coast since (Gaglioti et al 2019). I first saw this glacier in 1982 and its terminus stretched 3.5 km along the coast, a second terminus ended inland and was 3.2 km wide. Both of the terminus are piedmont fed by a significant accumulation area above 2300 m, that flows through a spectacular icefall from 1100 to 1800 m. This high accumulation zone helps make the glacier more resilent to warming temperature (Pelto, 1987). Berthier et al (2010) noted a ~0.5 m/loss average loss for glaciers in this region from 1962-2006, which has generated this retreat. The glacier because of its size and large piedmont lobe is slow to respond to climate change, 20 km2 coastal lobe and 10 km2 inland lobe.
La Perouse Glacier coastal terminus area indicating the three developing proglacial lakes, yellow arrows. False color Sentinal images.
Up to 2018 the coastal terminus was thinning, but had not experienced significant recession or proglacial lake development. There was significant marginal recession by 2018 exposing a forest overrun by the glacier in the 1860’s (Gaglioti et al 2019). In 2018 the inland terminus had developed 3 proglacial lakes wiyth a combined area of 0.4 km2. By 2023 the inland terminus lakes spread across 90% of the width of the terminus, with a combined area of 0.7 km2. In 2023 the main terminus had developed three proglacial lakes each, #1 at 0.12 km2, #2 at 0.16km2 and #3 at 0.36 km2. Lake #3 has numerous bergs indicating the ability to rapidly expand by calving, due to having a greater water depth. In just five years the debris covered area has expanded notably. This combination of expanding glacial lakes and debris cover is an indication of ongoing rapid decline. The changes here are simialr to that at nearby Brady Glacier and progressing on the same trend as Fingers Glacier. Look for further lake development in 2024 particularly in the coastal lobe.
The snow line on Mount Everest Region glaciers on May 1,, 2024 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes (5800-5900 m) are both snow free. The average snow line is 6050 m.
This is a update to a previous post examining high snow lines through the winter on Mount Everest Region glaciers. Here we examine imagery from October 2023 through early May 2024 illustrating the rise in snow line into January and the continue high elevation into the pre-monsoon season. The persistent high snow line over the last six months, indicates a lack of snow accumulation during the winter season. This is a dry season, yet typically leads to extensive, though not particularly deep snow cover. There were a few smaller snow events, but the snow cover did not persist indicating that ablation has continued even above 6000 m on Mount Everest. The lack of snow leads to less infilling of crevasses on Khumbu Glacier, which are further opened by persistent ablation. On May 1 there is evident blue ice and firn areas in the Western Cwm, above the Khumbu Icefall and on the Lhotse Face above the Western Cwm at the head of the Khumbu Glacier. The relatively bare slopes above the Western Cwm also cannot generate as much avalanches that would then accumulate snow in that basin. These same slopes will yield more rock fall, with more exposed unburied rock.
In the Khumbu Icefall velocities indicates by NASA ITS LIVE are ~1m/day which leads to considerable crevasse development in the six months from November into May with very limited snow accumulation and evident ablation, image below. This season is different than the high snow lines i 2020/21 that resulted from extraordinary January heat wave. Snow cover did develop at the end of the winter/early spring (Pelto et al 2021).
The snow line on Khumbu Glacier on May 1,, 2024 indicated by yellow dots on the Landsat image. Note that there are bare ice areas in the Western Cwm (WC) and on the Lhotse Face (LF).The snow line on Mount Everest Region glaciers on March 14, 2024 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes (5800-5900 m) are both snow free. The average snow line is 5950 m.
The snow line on Mount Everest Region glaciers on Feb. 11, 2024 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes (5800-5900 m) are both snow free. The average snow line is 6000 m.
The snow line on Mount Everest Region glaciers on Jan. 10, 2024 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes are both snow free. The average snow line is 5950 mKhumbu Glacier on Feb. 11, 2024 in Landsat image illustrating snow line near top of icefall at 6000 m, yellow dots. There is some blue ice showing on north side of Western Cwm (WC), Lhotse face too shadowed to see well, but some blue ice evident.The snow line on Mount Everest Region glaciers on Nov. 15, 2023 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes are both snow covered. The average snow line is 5800 m.The snow line on Mount Everest Region glaciers on Oct. 30, 2023 indicated by yellow dots on the Landsat image. Note that Nangpa La and Nup La-two high passes are both snow covered. The average snow line is 5700 m.Khumbu Glacier Icefall velocity from NASA ITS LIVE. Green arrows indicate primary rangeEverest Base Camp Precipitation from the National Geographic Perpetual Planet station.
Baird Glacier terminus tongue gone in April 26, 2024 Landsat image. Red arrow indicates now joined 5 km2 proglacial lake. Yellow dots terminus of Baird and North Baird Glacier
Baird Glacier drains the west side of the Stikine Icefield in southeast Alaska. It is the only glacier of the Stikine Iceifield that did not retreat significantly from 1960-2010. Pelto et al (2013) predicted the onset of significant retreat of this glacier, which like Brady Glacier had been slow to begin retreat despite thinning that was evident when I visited the glacier in 1984. The proglacial lake that has emerged with retreat has an area of 3.25 km2 and the glacier retreat is 2800 m from 1990-2024. The North Baird Glacier separated from Baird Glacier in 2019, with a proglacial lake extending downvalley to the tongue of Baird Glacier that separated this lake from the Baird Glacier proglacial lake until April 2024.
Baird Glacier in Landsat images from 1990 and 2023 illustrating retreat and proglacial lake expansion.Baird Glacier in false color Sentinel images from September 10 2023 and May 2 2024. Proglacial lake (PGL) expanded from 3.2 to 5.1 km². Tongue extending upvalley toward North Baird Glacier (NB) broke up in late April, yellow arrow.
Baird Glacier in false color Sentinel images from July 2022 and July 2023. Proglacial lake (PGL) expanded from 3.00 to 3.25 km² width of tongue extending upvalley toward North Baird Glacier (NB) has declined from 700 m to 400 m.
In 1990 the Baird Glacier was sitting on an outwash plain, with no lake at the terminus. The North Baird Glacier was 1 km wide where it joined the Baird Glacier. By 2015 the glacier has retreated 750 m and the lake (PGL) has an area of ~1 km². In 2022 the glacier has retreated leading to a lake expansion to 3.00 km². In July 2023 the tongue of ice extending across the front of the North Baird Glacier valley has thinned 40% since July 2022. The tongue remained throughout 2023 into April of 2024 before breaking up. This leaves the main terminus of the glacier more vulnerable to further rapid calving retreat. Baird Glacier is catching up to the rest of the Stikine Icefield that has experienced significant retreat, Dawes Glacier, Patterson Glacier and Great Glacier. With Sawyer Glacier retreating from tidewater in 2023.
Steffen Glacier in 2024 False Color Sentinel images illustrating calving events yielding bergs A,B,X and Y that have a combined area of 1.5 km2.Green arrow is Dec. 2023 terminus and yellow arrow April 2024 terminus. Each berg has consistent notation.
Steffen Glacier is the largest south flowing outlet of the 4000 km2 Northern Patagonia Icefield (NPI). Several key research papers have reported on the spectacular retreat of this glacier in recent years. Glasser et al (2016) reported that Steffen Glacier proglacial lake area expanded from 12.1 km2 to 20.6 km2 from 1987 to 2015, due in part to a 100 m snowline rise. Dussaillant et al (2018) determined annual mass loss of NPI at ~-1 m/year for the 2000-2012 period, with Steffen Glacier at -1.2-1.6 m/year. The result Steffen Glacier retreat from 1987-2019 was 4.4 km, ~137 m/year (Pelto, 2019).
On December Dec. 6, 2023 the terminus tongue has a narrow unsupported section that appears poised to calve (C). By Dec. 26, 2023 the glacier has calved berg C (0.4km2 ), joining other large bergs remaining from previous years D, E and F. Two more pieces A and B appear poised to calve. By Feb. 9 2024 berg B has calved, and by Feb. 24 berg A has calved, together they are 0.3 km2.
On April 14 two more large bergs X and Y have calved from the terminus. Berg X is the largest of the year at 0.6 km2, berg Y is 0.2 km2 . Terminus retreat from Dec. 2023-April 2024 is 1.5 km. The terminus tongue is again narrow and unsupported as the winter season begins, indicating that more large icebergs should be expected in the 2025 summer season. Millan et al (2019) indicate the area of tributary glacier convergence near the northwest terminus and above the glacier is 700 m thick, and that the glacier has been retreating along an area where the glacier bed is below sea level, though the terminus now is close to sea level.
Steffen Glacier in Dec. 2023 False Color Sentinel images illustrating calving event yielding berg C.Green arrow is Dec. 2023 terminus and yellow arrow April 2024 terminus.
Grace (G), Lucas (L) and Price (P) Glacier’s in 4-6-2024 Sentinel image top, yellow dots mark the 1987 terminus position when all reached tidewater, blue dots indicate 2024 terminus. Below is the South Georgia GIS with terminus observations from the BAS shown.
In 1987 Grace, Lucas and Price Glacier on the northern end of South Georgia Island each reached tidewater. Each had retreated less than 100 m since 1976. This is a very cloudy region and clear satellite image views limited. Here we examine Landsat images from 2000 and 2016, and a Sentinel image from 2024 to identify changes. Gordon et al., (2008) observed that larger tidewater and sea-calving valley and outlet glaciers generally remained in relatively advanced positions until the 1980’s. After 1980 most glaciers receded; many of these retreats have been dramatic including Twitcher, Herz, Ross, Hindle, Konig and Neumayer Glacier (Pelto, 2017).
By 2002 a Landsat image reveals that Grace and Lucas Glacier have retreated from the coast with new proglacial lakes forming between the terminus and the coast. Price Glacier main terminus is still filling most of a narrow bay, and the east side of the terminus is still reachig the coast. By 2016 Grace Glacier retreat has led to the formation of several small proglacial alkes, while Lucas Glacier retreat has generated one larger proglacial lake. Price Glacier has begun to retreat up a narrow embayment and the east side has almost lost connection with tidewater.
In 2024 Grace Glacier has retreated 1200 m, ~20% of its length in 1987. Lucas Glacier has retreated 1400 m, ~20% of its length. Price Glacier now only terminates in a narrow embayment ,has retreated 1700 m, ~23% of its length. Each glacier has limited area above 500 m, indicating that below this elevation glacier mass balance has been significantly negative over the last 35 years. The retreat here is similar to that of Konig and Turnback that have retreated from tidewater exposing new coastal regions that are being occupied by flora and fauna.
Grace (G), Lucas (L) and Price (P) Glaciers in 2002 and 2016 Landsat images as they retreat from tidewater.
Volcan Overo Glaciers at the end of the 2024 melt season in a false color Sentinel image from 3-30-2024. There is no sigificant area of snowcover remaining for the 3rd consecutive summer. The lake that had formed at Point A since 2018 has now drained. Fragmentation at point B, C, and D continue, while thinning at top of glacier is apparent with expanding bedrock knob at Point E.
Volcan Overo is a 4619 m high Andean mountain in Argentina with a relatively low sloped broad volcanic summit region above 4000 m that hosts a glacier complex that is shrinking and fragmenting. La Quesne et al (2009) observed significant annual thinning in the latter half of the 20th century on nearby glaciers in Argentina and Chile. A sharp increase in mass loss on Central Andean glaciers after 2009, including the Volcan Overo region, was reported by Ferri et al (2020). Here we examine Landsat images from 1986-2022 to identify longer term changes of the glacier and Sentinel images from 2018-2024 illustrating the persistent lack of an accumulation zone leading to recent changes, including the impact of the January 2023 heat wave (Washington Post, 2022). The persistent lack of an accumulation zone during the 2018-2024 period, highlighted in images below, in which no snow was retained as firn, indicates the glacier cannot survive (Pelto, 2010).
Volcan Overo in Landsat images from 1986-2022 illustrating area loss and fragmentation.
In 1986 there are four discrete glaciers around the caldera, covering ~12 km2 the largest E around the summit ranges in elevation from 4200-4500 m. D is an isolated area at 4000-4100 m. A,B and C is a single glacier extending from 3900-4300 m. F is an area of rapidly diminishing glacier ice.
In the early February image snowcover is good across all ice areas except F. In 2003 there is limited evident change with good snowcover across all except D. By 2013 A, B and C have fragmented into three separate glaciers and F is nearly gone. Only E has significant snowcover.
In 2022 C and D in the Landsat images have declined to less than 50% of their 1986 area, the overall Volcan Overo glaciated area has declined to ~8.1 km2. It is not quite mid-summer on January 8, 2022 yet all snowcover has been lost from the glaciers of Volcan Overo. The glacier remnants at F are now gone.
Volcan Overo Glaciers at the end of the 2018 melt season in a false color Sentinel image from 3-17-2018. There is no sigificant area of snowcover remaining. A lake is forming at Point A . At Point B this is a single glacier. At Point C an expanding ridge is still narrow and segmented. At Point D three glaciers areas are just losing contact and at Point E a small knob has emerged from ice cap.Volcan Overo Glaciers at the end of the 2020melt season in a false color Sentinel image from 3-11-2020. There is no sigificant area of snowcover remaining. A lake has formed at Point A . At Point D three glaciers areas are clearly separated.Volcan Overo Glaciers at the end of the 2022 melt season in a false color Sentinel image from 3-09-2022. There is no sigificant area of snowcover remaining. The lake at Point A is expanding . At Point B the glacier is separating into two parts.. At Point C an expanding ridge is now continuous segmented. Volcan Overo Glaciers at the end of the 2023 melt season in a false color Sentinel image from 3-09-2023. There is no sigificant area of snowcover remaining for the 2nd consecutive summer. The lake that had formed at Point A has expanded further. Fragmentation at point B, C, and D continue.
The impact of heat waves in 2022 and 2023 has taken its toll on the glacier.
From a Glaciers Perspective 