Stranded iceberg near the mouth of LeConte Bay. Note the furrow in the lower right corner. While still buoyant the icebergs are blown with the wind and pushed by currents, marking their course with such drag marks. Photo courtesy of Jack Beedle.
In April 2012 brothers Jack and Jay Beedle spent some time exploring and photographing icebergs from LeConte Glacier, Alaska. At low tide icebergs become stranded on the shallow low-angle beaches near the mouth of LeConte Bay.
A humpback whale breaches near icebergs from LeConte Glacier. Photo courtesy of Jack Beedle.
LeConte Glacier – near the towns of Wrangell and Petersburg in Southeast Alaska – is an outlet glacier of the Stikine Icefield and is the southernmost tidewater glacier in the Northern Hemisphere. In 1983 instructor Paul Bowen began the LeConte Glacier Survey. Each year a group of students from Petersburg High School visit and survey the terminus of LeConte Glacier.
LeConte-Glacier icebergs. Photo courtesy of Jack Beedle.
See more photos at GlacierChange.org on facebook. Thanks to Jack Beedle for sharing his photography at GlacierChange.org!
Links
Petersburg High School’s LeConte Glacier Survey
Shad O’Neel’s master’s thesis: Motion and Calving at LeConte Glacier, Alaska
For more on LeConte Glacier, Stikine Icefield and the glaciers of Alaska refer to: Satellite Image Atlas of Glaciers of the World: Alaska by Bruce Molnia
Study identifies longest record of annual glacier retreat in North America; retreat driven by summer temperature
Summary by: Matthew J. Beedle, Brian Menounos, and Roger Wheate
In 2007 Drs. Brian Luckman and Menounos stumbled upon an important series of moraines at the terminus of Castle Creek Glacier, BC (Figure 1). I was due to start field work on the glacier in a few weeks and one of my PhD supervisors, Brian Menounos, asked me to determine if the series of ridges were annual push moraines.
Figure 1: A view towards the terminus of Castle Creek Glacier, taken in September 2008. The series of roughly parallel ridges of sediment to the left of the stream are a portion of the annual push moraines that have been formed as the glacier recedes.
Annual push moraines form in winter when a glacier advances a meter or more, bulldozing sediment and rock into a small ridge. If summer retreat of the glacier outpaces these minor winter advances, then a long series of push moraines may form. The distance between these moraines varies much like the pattern found in tree-rings; warm, dry conditions tend to increase the separation between the moraines and vice versa.
Figure 2: Castle Creek Glacier just begins to pull away from this small push moraine in August of 2007.
Using aerial photos to date the sequence of moraines, we determined annual retreat from 1959 to 2007 (Figure 3). Castle Creek Glacier retreated about 700 meters during this period, averaging about 14 meters per year (Figure 4). Recession reached a minimum of 3 meters per year in the late 1970s, and a maximum of over 40 meters per year in the early 1990s. These changes coincide with temperature variability recorded during the period 1959-2007.
Figure 3: An image from 2005 showing glacier positions mapped from aerial photographs (blue lines) and push moraines (yellow lines). The blue line labeled ‘LIA’ is the position of the Little Ice Age maximum extent, a position that glaciers in western Canada were at in about 1850.
Although glacier retreat is dominantly controlled by summer temperatures, winter precipitation also plays a role. Our work shows a delay of about a decade between winter precipitation (snowfall) and the response of the glacier terminus – this delay or reaction time varies for a given glacier and depends on physical aspects of the glacier such as its length, thickness, volume, or steepness.
Annual retreat of Castle Creek Glacier is similar to observed recession for other glaciers in British Columbia, Alberta, Washington, and Alaska. A common climatic factor is the most likely explanation for synchronous behavior, and it appears that air temperature is that common factor.
Figure 4: Plots showing Castle Creek Glacier annual retreat (top) and cumulative retreat (bottom) updated through 2010.
Measurement of annual push moraines from high-resolution imagery provides an inexpensive method to record the magnitude of future glacier retreat (field surveys of glaciers are expensive and time consuming). Though such records are rare, they provide invaluable records of glacier change. We have identified other series of push moraines that front glaciers in North America using aerial photography and other high-resolution imagery available on GoogleEarth, and we encourage others to exploit this important proxy of glacier change. Since 2007, Castle Creek Glacier has continued to retreat and to form annual push moraines. We have updated our analysis through 2011 and will update our measurements in 2012 to extend the longest record of annual glacier retreat in North America.
Peer-reviewed paper:
Beedle, M. J., Menounos, B., Luckman, B. H., and Wheate, R., 2009, Annual push moraines as climate proxy, Geophysical Research Letters, 36, L20501, doi:10.1020/2009GL0395
Abstract available here, full text available with subscription
Links:
More information about Castle Creek Glacier
Additional content on the Castle Creek Glacier length change record
Learn about McBride, British Columbia (the point of access for Castle Creek Glacier)
Figure 5: Castle Creek Glacier at dusk. September 2010.
By Matthew J. Beedle
A century of change of Illecillewaet Glacier, British Columbia, in Glacier National Park of Canada.
In August 2011 I spent three days in Mt. Robson Provincial Park with Roger Wheate and Marlene Baumgart. Our primary purpose was to take a centenary repeat photograph of Robson Glacier. On our final day in the park, as we rounded Berg Lake on our descent to the trailhead, we met two fellow hikers. Thanks to Roger’s gregarious nature we began to have brief conversations as we leapfrogged down the trail – each of us stopping regularly to take photographs, drink some water, or adjust a pack strap. As luck would have it we had just crossed trails with Henry Vaux Jr. and his wife Charlotte.
In 1887 George Vaux Sr. brought his children (George Jr., Mary, and William) to the Canadian Rocky Mountains for the first time. Long train journeys from their home in Philadelphia to the glaciers of Banff, Glacier, and Yoho National Parks became regular summer expeditions. The siblings returned to the glaciers of the Canadian Rocky Mountains for decades, Mary the last to return in 1939, a year before her death.
In 1899 George and William collaborated on two papers that were published in the Proceedings of the Academy of Natural Sciences of Philadelphia, two of the earliest publications to document receding glaciers in western Canada. These papers include excellent sketch maps, early measurements of glacier flow and recession, and wonderful accounts of science and exploration from the late 19th century. They can be accessed here and here.
But perhaps the most lasting legacy of the early Vaux-family explorers are the thousands of glass plate and film negative photographs of the glaciers they visited, archived today at the Whyte Museum of the Canadian Rockies. Outfitted with glass plates and cumbersome tripods and cameras the Vaux family captured some of the earliest photographs of glaciers in western Canada.
Henry Vaux Jr. and sister Missy Vaux photographing Illecillewaet Glacier in 2002. In their hands they hold the 1902 photo taken from the same location by their grandfather and great aunt and uncle. This photo is used with permission from Craig Richards.
Henry Vaux Jr. – a professor of resource economics and expert in water policy at University of California, Berkeley – is the grandson of George Jr., and great nephew of Mary and William. Since 1997 Henry has been revisiting the sites (camera and tripod in hand) that his family members first occupied some 100 years previously. The results include brilliant photo pairs showing a century of change in the Canadian Rocky Mountains.
Meeting Henry and Charlotte was wonderfully fortuitous. To Henry’s credit he has provided GlacierChange.org with permission to display four of his repeat photographs in advance of his book (“Legacy in Time”), which will be published in the coming year. We look forward to announcing the publication of “Legacy in Time” at GlacierChange.org!
View Henry’s repeat photographs here: Vaux Family Gallery: Glaciers of the Canadian Rockies
Links
Learn more about Mary Vaux: Hunters of Knowledge and Peace: Mary Schäffer & Mary Vaux (Whyte Museum) or here on YouTube
Following glaciers’ progress a Vaux family tradition
The Vaux Family and the Canadian Alps
Whyte Museum of the Canadian Rockies
Vaux family fonds
Glacier National Park: History
Photographic History of the Illecillewaet Glacier
A guest post by Allen Pope
It sounds like a simple question, right? What color is a glacier? Snow is white, so a glacier is white…except after it gets pressed into glacier ice. Then, it’s a beautiful sapphire blue color (and I’m not the only one who thinks so – some artists do, too!). Glaciers can even be red where certain algae have started growing…or where debris, ash, or dust has accumulated on the surface, then they are a brownish/grayish color…and where the snow is older it will have melted a bit and so it looks a bit darker, too…
Suddenly, the color of a glacier isn’t such a simple thing to describe. Which is a problem, because the color of a glacier can be really important! Whether it is dark or bright will change how much energy the glacier absorbs and therefore how fast the surface melts. (Melting can sometimes darken the surface, enhancing this effect. Cool articles on that from NOAA and Meltfactor!) And if we are able to tell apart the slightly different colors of new snow and year-old snow, it provides a powerful tool for being able to measure the size of the glacier’s accumulation area, a value VERY closely related to the glacier mass balance.
My research is focused on getting more of a handle on the “color” of glaciers, not just in the visible wavelengths but also in the infrared. I compare measurements from the field to airborne and satellite imagery of the same glaciers (lots of pretty satellite images from NASA Earth Observatory). In this way, I am looking into what types of data will potentially be able to help us best monitor glaciers as well as how to take advantage of the satellite data record that is already archived.
Fieldwork pretty much entails walking around on a glacier’s surface and pointing our sensor at the snow or ice surface (my fieldwork blog from Svalbard; photos from Iceland 2011). By comparing every surface measurement with a reference panel at the same time (image above), we make sure that all the measurements are intercomparable even if light conditions are different. We record the reflectance of the surface of a range of wavelengths as in this graph.
Then, we obtain satellite images, each of which contains information in not only the red, green, and blue, but also near infrared, and shortwave infrared. Each image is broken up into “classes” of groups of similar pixels which are then averaged together. Here’s a shot of what this looks like on my computer screen.
Finally, we compare the field data with the satellite data. In this graph (below) the continuous lines are the field data and the bars are groups in the satellite imagery. You can see immediately that some bars and lines match up well while others do not. There are many reasons for this, the most important of which is that while field data are measured at a single point, the satellite images measure pixels which are 30 meters across – so there’s a lot of mixing which takes place! My job is to figure out the best way to match the lines and the bars so that the field data can explain the satellite data.
My PhD is still in progress, so I can’t give you any of the final answers yet. I presented my intermediate results of satellite and in situ measurements at a very large conference in December, and now I’m moving forwards with some fresh ideas! I’m looking forward to getting a good handle on the remote sensing techniques and applying them more widely. Until then, keep checking out GlacierChange.org
Allen Pope is a PhD student studying the remote sensing of glaciers at the Scott Polar Research Institute in Cambridge, UK. You can find out more about him and his research at about.me/allenpope or follow him on Twitter @PopePolar.
This repeat photo pair came about through good fortune as opposed to a dedicated effort – I didn’t know of the 1929 photograph when I took the 2004 image. Fortunately the locations of the plane in each photo weren’t too far off (the 2004 image was taken from a bit higher altitude). The retreat of West and East Twin glaciers, Alaska is apparent – so to are changes in aviation since 1929!
Along with this repeat photo pair we have just completed an album in the GlacierChange.org Scrapbook for West and East Twin glaciers, which includes additional details about these glaciers, and some quantification of the surface area change from 1929 to 2011.
You can also view and explore these “Twin Glacier” outlines in Google Earth: Twin Glacier Extent Change: 1929 – 2011
