Castle Creek Glacier – 55 Years of Retreat

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By Matt Beedle

The longest continuous record of annual length change for a North America glacier now stands at 55 years (1959-2013).  In 2013 Castle Creek Glacier retreated 26.3 meters, the fifth largest annual measurement since 1959.  Total 1959-2013 retreat now stands at 803 m, with an average annual rate of 14.6 m.

dL-combi_59-13Annual length change of Castle Creek Glacier in meters (top), and cumulative length change in meters (bottom).  Both plots include data from 1959 to 2013.  A full discussion of the methods used to derive this data set can be found here.

Glacier retreat over decades can be dramatic.   For instance, Castle has lost nearly 2 km2 of surface area since 1952, most of it near the terminus.  Repeat photography of glaciers typically uses pairs of images separated by multiple decades, revealing this stunning multi-decade change.

 

castle_1952-2011_aerial-photosTwo aerial photographs of the terminus area of Castle Creek Glacier.  The 1952 image is from the National Air Photo Library, Natural Resources Canada.  The 2011 image includes the near infrared band – vegetation appears red.

In my numerous trips to Castle Creek Glacier over the past six years I’ve been no less moved by the annual changes of a much smaller magnitude, however.  The change we see around us is always in relation to scale, proximity and familiarity.

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One of my annual tasks at Castle Creek Glacier has been to walk the terminus of Castle Creek Glacier with a high-precision GPS on my pack, mapping the glacier margin and measuring annual change.  This annual walk – often times more of a scramble – reveals a great deal. The revelation is in terms of quantifiable glacier retreat, but also a more subjective experience of glacier landscapes and glacier change.  John Muir – reflecting on a brief exploration of the terminus area of Baird Glacier, Alaska in 1879 – captures this experience well:

“The whole front of the glacier is gashed and sculptured into a maze of shallow caves and crevasses, and a bewildering variety of novel architectural forms, clusters of glittering lance-tipped spires, gables, and obelisk, bold outstanding bastions and plain mural cliffs, adorned along the top with fretted cornice and battlement, while every gorge and crevasse, groove and hollow, was filled with light, shimmering and throbbing in pale-blue tones of ineffable tenderness and beauty.”

-John Muir, Travels in Alaska

Along with mapping the glacier margin and annual retreat, I’ve had the opportunity to observe and photograph Castle Creek Glacier’s annual changes.  With each visit I’m astonished by the volume loss, change in form and alteration in character that is quantified blandly (yet importantly!) in our measurements of change.  These repeat photographs, dating back to 2007, don’t show the marked change of repeat photos separated by decades. They do, however, catalog the more experiential understanding of the annual glacier change of Castle Creek Glacier.  If you’re fortunate enough to have a ‘local’ glacier, make an effort to pay it a visit each year – you will be richly rewarded.

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2013 Field Research Teaser: Zillmer Glacier, BC

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By Matt Beedle

In 1939, Raymond Zillmer and Lorin Tiefenthaler ventured into the Canoe River basin to fill voids and correct mistakes in the early maps of this rugged part of the Cariboo Mountains of British Columbia.  The high-mountain sources of the Canoe River had been viewed from afar, but not yet explored in any detail.  A peak – which Zillmer and Tiefenthaler referred to as ‘Half Dome’ – and a glacier now bear Zillmer’s name.

Our May 2013 base camp on Zillmer Glacier.  Chamberlin Peak is in the background.  Photo by Matt Beedle.

In May of this year, a small group from University of Northern British Columbia returned to this stunning corner of the Cariboo Mountains to begin monitoring Zillmer Glacier.  The purpose of this field research – funded by the Columbia Basin Trust – is to establish ongoing studies at a site that represents the glaciers of the northernmost portion of the Columbia River basin.

We plan to return to Zillmer Glacier in the next few days and complete measurements of the 2013 melt season.  Please stay tuned to GlacierChange.org for a full report upon our return.  Until then, enjoy these clips from our work in May.

2013 Field Research Teaser: Zillmer Glacier, BC from GlacierChange.org on Vimeo.

35 Years at Bear Glacier, BC

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By Matt Beedle

Repeat photography tells a story.  Traditionally, the story that is often told is one of landscape change.  In the case of glaciers, the common story is one of melting and retreat.  While this story is captivating to me – particularly in regard to the amazing dynamism of glaciers (they’re alive!) – I’m more intrigued with a wider plot:  the inclusion of a more human story that might be told through repeat photography.  Here is one of these stories.

This story starts about three years ago at the British Columbia Archives at the Royal BC Museum in Victoria.  I spent the day looking for historical images of glaciers that I might repeat.  (While you can browse many historical images online, there are many photos that have yet to be digitized.)  In particular I was looking for glaciers I recognized, glaciers that would be relatively accessible, and images that were older but of high quality.  I found some quality images that day that lead to repeat photo pairs of the Bear, Salmon and Berendon glaciers of BC.  However, I also found some photos that intrigued me not just for their potential to show glacier change, but in the possibility to use them to tell a different story of change, a story of human change on a glacial timescale.  The historical image featured here is from the year of my birth (1978); it is of Bear Glacier and in the foreground is highway 37A with a logging truck kicking up a dust cloud as it rumbles towards the port in Stewart, BC.

Bear Glacier, BC as photographed in 1978.  This photo (I 66512) is used by GlacierChange.org with the permission of the Royal BC Museum, BC Archives.

So, two days ago I set off on a repeat photography adventure from my home in Terrace, BC.  I had with me a small stack of historical photos of Bear, Salmon and Berendon glaciers that I hoped to repeat, but my main goal was to repeat the 1978 “logging truck” photo.  As I drove the three hours north from Terrace to Bear Glacier I was filled with more than a bit of doubt:  Do logging trucks (loaded with logs) still pass by on their way to Stewart?  How often?  Are the drivers working on this particular Tuesday in July?  Is the spot where this 1978 photo was taken now covered in dense vegetation?  If I can get to the right spot, how long will I have to sit and wait for a logging truck?

Within a couple minutes of turning to the west onto highway 37A at Meziadin Junction a heartening sign rumbled toward me heading east:  an empty logging truck.  “OK, this may yet work,” I thought to myself.  As Bear Glacier and Strohn Lake came into view I slowed down and started to look at the hillside from where the 1978 photo was taken.  Another good sign:  not much vegetation had taken root on the steep slope in the past 35 years.

I parked my car a bit further down the road, realizing that I didn’t necessarily want it in the shot.  As a swarm of black flies attacked my arms and neck I packed camera, tripod, and a copy of the 1978 image, as well as enough water and food to get me through a day of waiting on a hillside.  I started down the road and a loaded logging truck roared passed.  I was heartened that I wasn’t there in vain, but, at the same moment, also fearful of how long it might be until the next one came by.

After about a half hour of scrambling about the hillside, I settled on a spot that was likely within 20 m of the position where the 1978 photographer stood.  This is done by lining up features on the ridges in the foreground with those in the background to match the 1978 photo (a nice video on this technique).  I set up my tripod, mounted my camera, and was working on determining the focal length and getting the same framing of the 1978 photo when a second logging truck came around the bend.  I had a few seconds to switch my camera to burst mode and make a minor tweak to the framing before capturing a handful of shots as it rolled through the scene.  Doesn’t get much easier than that!

The framing wasn’t perfect, but I had captured a passable shot within about 5 minutes.  I rationalized that the rigs might be passing by roughly on the half hour, or perhaps hourly, so I made some further tweaks to the framing and exposure and eagerly anticipated the next truck.  For the next 2.5 hours I ate lunch, waved at tourists who noticed the strange guy standing on the hillside above the road, sketched the view, swatted flies and mosquitoes, stretched, cursed at caravans of RVs that parked in what would be the shot had a logging truck passed by, checked and re-checked the framing of the shot, was excited then let down by ore trucks that sounded like their cellulose-hauling brethren . . .

Waiting for a Logging Truck – Bear Glacier, BC from GlacierChange.org on Vimeo.

It was time to go.  There were other glaciers to visit and I did have an OK shot.  I packed up and headed back to the car.  On the way, I took two more Bear Glacier repeat images from locations along the roadside.  Back at the car the black flies were still swarming.  I ran around the car, hoping to lose the biting hoard before opening the car door and jumping quickly inside.  As I pulled out of the dirt siding, another logging truck – seemingly a perfect match of the one in the 1978 image – thundered by.  Oh well, c’est la vie.

For me, this photo pair reminds me of a beautiful day in a stunning corner of northwest BC, but also leads to reflection on change, both in terms of glacial time and human time.  What are we to make of 35 years?  The 35 years of one’s life, of visitors to Bear Glacier, of rising temperatures and melting ice, of a natural resource as an economic anchor of a rural town, of forests that once were.  The glacier becomes a backstory, a marker of change on a more geologic timescale, a yardstick with which we might measure change in our own lifetimes.  What adventures from the past 35 years shape your story?  Where will the next 35 years lead?  The story continues . . .

Glacier Research History: The Beginnings of the Juneau Icefield Research Program

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By Matt Beedle

[NOTE:  A revised version of this post appeared on the JIRP blog.]

In August and September of 1941, a team that included William O. Field, Jr. and Maynard M. Miller (amongst others) studied the glacier termini of Glacier Bay and the inlets and fjords near Juneau, Alaska (Field, 1942).  Field and Miller would later recall that it was during this expedition of the 1940s that it began to become apparent that it was necessary to study the upper reaches of these Alaska glaciers to understand their disparate behavior (Field and Miller, 1950).

The terminus of Taku Glacier photographed by W. O. Field during the expedition of 1941 (Field, 1941).

Until the 1940s the vast bulk of scientific observation of Alaska glaciers was of their termini, with many hundreds of stations established for repeat photography and surveying of glacier length change.  What was apparent – and what dominated as the key ‘problem’ in the glaciology of southeast Alaska at the time – was how some glaciers (most notably those of Glacier Bay) were receding dramatically, while others (such as Taku Glacier) were advancing vigorously.  What was the cause of this dichotomy?  Field and Miller were being drawn to the upper reaches of these glaciers as the best place to uncover what was driving the terminus changes that had been observed for decades.  However, these upper reaches – the massive icefields of the Coast Mountains  – were still, for the most part, unexplored:

“Taku Glacier heads far back in the mountains, no one knows where . . .”

–Israel Russell, Glaciers of North America, 1897

At the American Geographical Society in 1946 Field and Miller began to collaborate on what would become the Juneau Icefield Research Project (Field, 2004).  In 1948, with American Geographic Society funding, Field and Miller initiated which was envisioned then as:

“ . . . a program for which would initiate over a period of years comprehensive studies not only of the Juneau Ice Field but on other representative ice masses in both North and South America . . .”

–Field and Miller, The Juneau Icefield Research Project, 1950

Juneau Icefield Research Project (JIRP) work on the icefield began in the summer of 1948 with a reconnaissance party in search of routes to access the accumulation area of the Juneau Icefield and to begin to determine the gear and logistics necessary to carry out thorough investigations.  Over the course of three weeks a team of six carried out this early reconnaissance and also initiated glaciological, geological, botanical and meteorological studies.

Following the early, more exploratory years of JIRP in the late-1940s, extensive field research in the 1950s was led by a host of collaborators, including Calvin Heusser, Art Gilkey, Ed LaChappelle, and Larry Nielson along with Field and Miller.  These early years of JIRP are brilliantly chronicled in a retrospective by Calvin Heusser, complete with wonderful journal entries from the early expeditions on the Juneau Icefield (Heusser, 2007).

1995 Landsat image of the Juneau Icefield

From 1948 to 1952 JIRP research focused on the Taku Glacier, but in 1953 research efforts expanded to include the smaller, more accessible Lemon Creek Glacier.   Studies from 1953 to 1958 focused on detailed micrometeorology and mass balance of Lemon Creek Glacier and continued – yet with a reduced focus – study of Taku Glacier mapping, mass balance and meteorology.  Geobotanical studies to reconstruct historical glacier positions were made on a more limited basis, with small teams exploring more distant outlet glaciers of the Juneau Icefield such as the Gilkey and Tulsequah glaciers (Heusser, 2007).

In the late-1950s and early-1960s JIRP the ‘Project’ became JIRP the ‘Program’.  This transition, and subsequent half-century of JIRP, was lead by the husband-and-wife team of Maynard and Joan Miller.  During this time JIRP became an annual eight-week expedition across the Juneau Icefield from Juneau to Atlin, BC.  Each year high school, undergraduate, and graduate students, along with staff and faculty, traverse the Coast Mountains.  Along the way they continue the annual monitoring of the glaciers of the Juneau Icefield, participate in new research, and collaborate on the operations of a large-scale expedition.

While this post only scrapes the surface of an incredible history of glacier research, one of the lasting legacies of JIRP has been its role in inspiring young scientists, explorers and artists.   Another class of JIRPers has yet again embarked on this transformative experience, with the 2013 cohort of 25 students leaving Juneau last week for the first leg of the journey across the Juneau Icefield.

Now under the direction of Dr. Jeffrey Kavanaugh (U. Alberta), JIRP has embarked on a new adventure with regular blogging from the icefield.  GlacierChange.org was privileged to host the first year of JIRP blogging during the 2012 expedition, and you can follow the 2013 journey on the blog of the new JIRP website.

References

Field, W. O. 1941 Taku Glacier: From the Glacier Photograph Collection. Boulder, Colorado USA: National Snow and Ice Data Center/World Data Center for Glaciology. Digital media.

Field, W. O.  1942.  Glacier Studies in Alaska, 1941, Geographical Review , 31, 1, 154-155.

Field, W. O.  2004.  With a Camera in my Hands:  William O. Field, Pioneer Glaciologist:  A Life History as Told to C. Suzanne Brown, University of Alaska Press, Fairbanks, 184 pp.

Field, W. O. and Miller, M. M.  1950.  The Juneau Ice Field Research Project, Geographical Review , 40, 2, 179-190.

Heusser, C. J.  2007.  Juneau Icefield Research Project (1949-1958):  A Retrospective, Developments in Quaternary Sciences, 8, 232 pp.

Russell, I. C.  1897.  Glaciers of North America, Ginn and Co., Boston, 220 pp.

Links

Juneau Icefield Research Program

 

Bridge Glacier and the Life-Cycle of a Calving Glacier

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By Matt Chernos

[Note:  This is a guest post by Matt Chernos, a Master of Science student at the University of British Columbia.  Read more on Matt's blog Bridging The Gap.  Thanks, Matt!]

Bridge Glacier in the summer of 2011.  Photo by L. MacKenzie

Bridge Glacier is located in the Pacific Ranges of southwestern British Columbia, Canada, between the Coast and Chilcotin Mountains. The glacier is an outlet of the Lillooet Icefield, about 175 km north of Vancouver. Beyond being the source of my MSc thesis, Bridge Glacier is important because it is the source of the Bridge River, and the Bridge River Hydroelectric Project, which supplies British Columbia with 6-8% of its electrical supply, leading some to call it a giant “melting battery“.

Bridge Glacier is also an interesting study because it sits in a lake, known unofficially as “Bridge Lake”, allowing calving to be a significant source of ice loss from the glacier. This wasn’t always the case though. Until the late 1980s, Bridge Lake was relatively small and shallow. Since 1991 though, Bridge Glacier has retreated substantially, and has allowed the lake to triple in size (up to 6 km^2 in 2012). As we have already seen on this blog, and throughout scientific literature, glaciers that flow into large bodies of water retreat somewhat less directly than the traditional response of warmer temperatures driving retreat. The question is, how much does the lake actually affect Bridge Glacier’s retreat?

One easy way to figure out glacier retreat rates is to check Landsat Imagery (available easily through their aptly named “LandsatLook Viewer“). Satellites capture images roughly every 16 or so days. Unfortunately, if you’re studying an area that is pretty cloudy, 80% of your images will be blobs of cloud (which can look really cool, but doesn’t really help reconstruct glacial histories). Images for Bridge Glacier go all the way back to 1972, with a few gaps in the data due to clouds and low temporal resolutions in the 70 and early 80s. By collecting an image from late September every year, I was able to compare two sequential images and measure how far the glacier retreated.  Putting all the years together, here is an animation of Bridge Glacier 1972-2012.

Bridge Glacier 1972-2012. If the animation isn’t running on your browser, click the picture.

And again putting into a “science form” in a graph (below):

(a) Bridge Glacier cumulative retreat (b) Winter Precipitation Anomaly (snowfall) (c) Summer Temperature Anomaly (d) Mean Annual Flow Anomaly (Bridge River Flow). All figures explained in the text.

To get a better handle on the graph, (a) is the cumulative retreat of Bridge Glacier from its position in 1972. Cumulative values are often seen because individual years have a lot of variability, which can distort what is otherwise a really clear trend of retreat.  (b) is the winter precipitation anomaly (November-April inclusive). Anomalies are often used in climate science to clearly illustrate whether any given year was above or below average. For this graph, average winter precipitation (snowfall as water equivalent to eliminate snow density discrepancies) was taken for 1972-2012. (c) is the summer temperature anomaly (May-October). Again, positive (red) values indicate hotter than normal summers. (d) is the mean annual flow of Bridge River at the edge of the glacier. Mean Annual Flow (MAF) is a measure of how much water passes through the Bridge River, and is an excellent indicator of how much melt there is in any given year.

The first thing that jumps out to me in this graph, is that the retreat rate is ‘step-like’.  Until 1991, the glacier is retreating pretty consistently, but that summer, things become more irregular. 1991 and 1992 have fairly large retreats, but then the glacier stays pretty constant for a couple years until it retreats again dramatically in a couple bursts. In fact, most of the retreat since 1991 occurs in a couple years of large bursts 0f dramatic retreats.

One of the largest retreats occurred in 2005 between July 27 and August 15:

July 27, 2005

August 12, 2005

September 5, 2005

Hopefully this photographic evidence is convincing enough that this ‘step-like’ or ‘staircase’ retreat is a product of calving as the glacier terminus is destabilized by the lake that it is floating in. The question that remains, though, is how much of this can we blame on Bridge Lake, and how much of it is a product of a changing climate.

To do this, we can run a numerical experiment: How would Bridge Glacier have retreated if Bridge Lake wasn’t there? 

We’ve already discussed how a glacier’s change in length is a product of changes in temperature, buffered by its individual climatic sensitivity, and the period it takes for this change in temperature to fully affect the terminus, known as the response time.  If we calculate these variables for Bridge Glacier, and combine it with temperature data, we can predict how the glacier would have retreated had it not been for the lake.

Modeled retreat for Bridge Glacier. The LOESS line is the modeled retreat rate smoothed to even out the statistical ‘noise’ of temperature data.

What this shows is that until 1991, climate projected retreat is very close to what we actually observed at Bridge Glacier. However, from 1991 onwards, once Bridge enters the ‘staircase’ stage, it retreats a lot faster than projected. If we go back to the animation of Bridge Glacier’s retreat, we can see that 1991 is, not coincidentally, when we start to see icebergs in the lake. All of this suggests, once again, that once the glacier begins to calve icebergs, its retreat becomes less a product of warm temperatures, and more of calving events.

If calving is in fact driving the accelerated retreat of Bridge Glacier, as this model suggests, it isn’t all bad news. Eventually, the glacier will retreat far enough back, and high enough, that it will no longer spill into the lake. Once the glacier reaches this point, it should, once again retreat more in line with the gentle climate-controlled retreat (albeit still retreat!) projected in the model. Once it does so, it will have ended its calving phase, and will once again respond more directly to climatic trends.

Links

A more technical write-up of Bridge Glacier recession and relations to climate and calving

About Matt Chernos

Matt’s Blog:  Bridging The Gap