mount cheops final 477 - University of Victoria€¦ · Mount$ Cheops is accessed via$ the Balu...
Transcript of mount cheops final 477 - University of Victoria€¦ · Mount$ Cheops is accessed via$ the Balu...
Mount Cheops Cirque Glacier: Response of a Small Debris Covered Glacier to Climate Change S.J. Rubin V00197024 Geography 477, Field Studies in Physical Geography, University of Victoria. (E-‐mail: [email protected])
ABSTRACT Global climate change is evident in the alpine regions of British Columbia, effects of which were observed and explored during field school investigations of a microclimate cirque glacier on Mount Cheops in Glacier National Park of Canada. Rapidly receding glaciers are becoming an important water resource concern for British Columbia. We are beginning to understand that our water supply is not inexhaustible, similar to that realization regarding BC’s timber resources in the late twentieth century. Water is vital not only as a resource for human use; changes in glacial hydrological systems are also changing patterns of vegetation and wildlife that are adapted to alpine conditions. A hydrological survey was conducted to estimate the contribution of the Cheops glacial melt waters into the Connaught Creek drainage system, by comparing discharges at various locations along the valley bottom and within the cirque. Simple observations, such as water clarity and discharge fluctuations during the day, help to provide insight into the glacial hydrological system. Another particular consideration is the effect of debris cover in helping to preserve glacial ice, which was observed on more than half of the Mount Cheops glacier. Using a series of air photos, a temporal assessment of the Cheops glacier is made possible. There have been very few studies on small glaciers in the area, and the ones that have been done, including this one, are limited by being conducted in one location at one time. This project seeks to understand the significance of small glaciers and their role as water resources, and how debris cover slows the retreat rate of some glaciers. There is no inventory of the small glaciers that are disappearing, and basically no baseline study to build our knowledge upon. This paper will illustrate the importance of continued studies and monitoring of these crucial water resources, which are threatened by increasing global air temperatures, and other climate change variables. Keywords Cirque glacier; debris cover; microclimate; climate change
BACKGROUND
LOCATION
Mount Cheops is located at the summit of Rogers Pass within Glacier National Park
of Canada in the Selkirk Mountain range. The park is approximately 48 kilometers
east of Revelstoke. Mount Cheops is accessed via the Balu Pass trail, with the
trailhead at the Rogers Pass Visitor Center on the Trans-‐Canada Highway. The
Selkirk Mountains are a prime example of interior rainforest, receiving
approximately 2000mm of
precipitation per year (Parks
Canada). Compared with our
800mm on the coast in
Victoria, we see that Glacier
National park is very wet or
very snowy all year round.
The study site in the north
cirque of Mount Cheops is
challenging to access, and includes bushwhacking a short distance through nearly
impenetrable aspen groves, followed by scrambling up a steep boulder field until
reaching the terminal moraine and beyond.
SIGNIFICANCE OF CHEOPS ICE IN THE SELKIRKS
The Selkirk Range and surrounding mountainous regions are extensively glaciated.
There are a few large glaciers and ice fields, such as the Illecillewaet Nevé, but there
are a vast amount of small patches of glacier ice. This is due primarily to the
influence of microclimates
produced in mountainous areas.
The main requirement to produce
a small microclimate glacier is a
large north facing headwall,
creating nearly constant shade on
the slope below. The headwall
also helps build deeper snowpack
in the winter, because it is too
steep for snow to stick to, creating
avalanche accumulation on the
slope below. These two factors
have helped to create the small
Figure 1, Topographic map of Rogers Pass
Figure 2, False colour satellite image of the northern Selkirk Mountains, blue is glacier ice.
glacier on Mount Cheops, and many other glaciers in the region, and around the
world. In this false colour image, compare the amount of large blue areas with the
small blue areas. It can be argued that the accrued influence of all the small glaciers
combine into a very important water resource. If the influence of the Mount Cheops
glacier were studied on it’s own, it would be insignificant, so this study assumes that
the Mount Cheops cirque glacier is representative of a type of glacier that is very
common in the region, and that type of glacier’s combined abundance is a significant
resource. The Cheops glacier is very small, about 1/1031 the surface area of the
Illecillewaet Nevé, yet the Cheops glacial discharge is 1/8th of the Illecillewaet
discharge measure during field school. It is also important to note the altitude of
tongue of each glacier; the Illecillewaet Glacier terminus was at approximately 1975
meters above sea level this summer, compared to the Cheops tongue at about 1800
meters. The effects of microclimate at the Cheops glacier sheds light on this
discrepancy. The disproportionate surface area to runoff is likely due to the
difference in exposure of glacial ice to direct sunlight. The Cheops glacier is mostly
in the shade and covered by insulating debris, leaving it susceptible to melt, due to
warm air temperatures. The Illecillewaet Nevé, however, is entirely exposed to
direct insolation, and is therefore susceptible to sublimation, or a direct phase
change from solid ice to water vapour. This is a direct rational for believing that
small microclimate glaciers are an important source of freshwater for river
headwaters: they melt more than they evaporate, unlike the bigger glaciers in the
region.
MICROCLIMATE
The Mount Cheops cirque glacier is greatly influenced by a unique geomorphic and
climatic system. The temperature range in the region is very prone to lots of
freeze/thaw cycles, which is essential for the weathering processes involved in
cirque formation. “Cirques are often preferentially oriented according to the
direction of solar radiation” (Graf, 1976). “Cirques result from two separate groups
of processes: 1. Mechanical weathering and mass wasting, and 2. Erosion by cirque
glaciers” (Ritter et al., 2002). The north side of the mountain has a very steep
exposed rock headwall that descends from the summit down to a cirque valley that
is occupied by the small glacier. The layout of this valley is consistent with
descriptions of cirque formation and morphology. The large northern facing wall
provides permanent
shade on most of the
glacier, with only a small
portion of debris-‐covered
ice extending far enough
from the wall to receive
direct sunlight at midday
during the summer
months. The headwall
serves two functions in
the balance of the glacier;
lots of snow falls on the wall, but it is too steep for snow to cling to during the winter
months, avalanches deposit the snow from the wall down on the surface of the
glacier, creating a large cone of snow at the edge of the headwall. The other function
that the headwall serves is a source for debris cover. Alpine areas are subject to a
strong freeze-‐thaw cycle, creating very extensive mechanical weathering in the area.
The headwall is eroding almost constantly, and provides an enormous amount of
debris to cover and preserve the glacier ice.
DEBRIS COVER
The Cheops cirque
glacier is significantly
influenced by the
presence of debris cover.
The debris is primarily
composed of large
angular boulders, but
Figure 3, Base of last winter's avalanche cone on top of older deposits.
Figure 4, Debris cover high on the glacier, 450 meters below the head wall.
there are areas of ice covered with fine silty sediments. There is an enormous
amount blocky debris cover over a large area, creating landforms typical of rock
glaciers. These landforms include arcuate ridges of debris and hummocky ablation
moraines, which are consistent with findings at other rock glaciers, such as the
Wenkchemna glacier in the Rocky Mountains (Gardner, 1977). The Cheops rock
glacier feature is ice-‐cored, “containing subsurface ice with a superficial coating of
rock fragments (up to several meters thick)… The coarse block layer may act as a
thermal filter to protect the permanently frozen ice core if snow cover is thin or
absent” (Ritter et al.,
2002; Humlum, 1997).
Gardner’s
Wenkchemna paper
also suggests that
debris cover is
responsible for
creating a lag time in
glacial activity relative
to non-‐debris covered
glaciers in the region.
The Wenkchemna glacier, for example, was estimated to lag 70 years behind other
glaciers reaction time to climatic change.
METHODS
SITE SELECTION
The Cheops cirque glacier was selected as a safe site to explore over the coarse of
two daytrips. Other glaciers in the area are more difficult to access, and would have
limited the amount of time at the site for observations. The Cheops cirque is located
about 2 km from the Glacier Compound, and the Balu Pass trail allows close access
to the site. The trail is along Connaught Creek, and accessing the cirque is easiest at
the confluence of the cirque drainage creek into Connaught Creek. The drainage
from the glacier descends a steep block field, with its loose and wet rocks, it is a
Figure 5, Hummocky ablation moraines indicate rock glacier stagnation.
dangerous area to travel through. A thin, active glacier is located in the cirque along
the steep headwall, with ice extending over 1 km down slope from the wall. There
was nearly constant rockfall all over the headwall, posing a hazard while exploring
on the glacier. The Cheops cirque glacier proved to be a dynamic landscape, with
changes noticed just between the two days. One change, for example, was the
collapse of a snow bridge that was present over a crevasse on the first day, but was
gone on the second day. Another change was due to weather conditions, while the
first day was clear; the second day’s weather conditions were fog and rain. The
drainage creek acted very differently between the two days. Unfortunately, the
hydrological survey was only conducted on day two.
SURVEY – MAKING A FIELD MAP
Simple surveying techniques using a digital rangefinder (Nikon Forestry 550),
measured distances and angles between landmarks. These were used to create an
estimate of the size of the glacier, and to determine how much wastage has occurred
based on the height of lateral moraines above the surface of the ice. This height
difference indicates the amount of glacial wastage, which is an important
consideration because glaciers
do not only recede at their
tongues. The field survey also
attempted to calculate the
amount of glacial surface area
that is debris covered compared
to the surface area of exposed ice
and firn.
TRANSECT PROFILES
A topographical profile is a good visualization for understanding how the aspect and
topography of the Cheops cirque creates a microclimate glacier, with a good
Figure 6, The Mount Cheops cirque is an intricate setting for surveying.
accumulation zone, lots of source rock for debris cover, and protection from direct
sunlight. A cross sectional profile of the glacier and moraines helps to illustrate the
down wasting of the glacier.
AIRPHOTO & FALSE COLOUR INTERPRETATION
Airphoto interpretation proved to be challenging. The first obstacle is obtaining the
airphotos of the location. The airphoto warehouse located in the Vancouver Island
Technology Park houses provincial airphotos dating back to the 1950s. Airphotos of
Mount Cheops were found from 1951, 1986, 1991 and 1996. These airphotos do not
easily match up, as scale and angles from the plane to the glacier were different in
all of the photos. Instead of creating the classic receding glacier airphoto image, the
four images are displayed next to each other, so that the changes on the landscape
can be easily identified. The classic interpretation method of drawing the glacial
extent from previous years did not work well because of the challenges associated
with lining up landmarks in all four photos. The extent of ice does not appear to
have changed drastically over the roughly fifty year period, but the debris covered
area of the glacier seems to be completely reworked between all of the photos.
False colour satellite images are useful in assessing the glaciation in the region. The
blue areas of these photos clearly shows exactly where glacial ice is located. Using a
grid overlay, the surface area of the Mount Cheops glacier was compared to the
Illecillewaet Nevé. Using a small grid, the Cheops glacier was first compared to the
Ursus Major glacier, and then that glacier was compared to the Illecillewaet using a
larger scale grid. The comparison between the Cheops glacier and Illecillewaet is
relevant because drainage data was collected from both sites. All of the Cheops
glacier runoff converges at a creek just above the Connaught Creek, allowing for the
measurement of all of the Cheops runoff. At the Illecillewaet, however, runoff data
cannot be assumed to be of the entire Nevé, because it likely drains through various
systems, but discharge was collected at the Illecillewaet River. Using the false colour
photo surface area comparison, the comparison of discharge from the two locations
becomes a meaningful measurement.
HYDROLOGICAL BASELINE STUDY
Discharge measurements were taken at various locations, and at various times,
including repeat measurements at some locations. The goal of these measurements
was to determine how much water the Cheops glacier contributes to Connaught
Creek. To do this discharge was measured above and below the confluence of the
Cheops drainage into Connaught creek, and the main Cheops drainage creek itself.
Also, to further understand the hydrological processes of the Cheops glacier, melt
water discharges were measured along transects below the glacier. This was done in
an attempt to estimate the amount of surface runoff near the terminus of the glacier
compared to the discharge at the valley bottom, with a presumption that a large
portion of the total melt water travels down slope beneath the surface. Because it
was raining during the hydrological survey, observations of water quality were
important. It is easy to discern which creeks originate at the glacier because that
water was heavily sedimented, while rainwater runoff was clear.
RESULTS
FIELD MAP & TRANSECTS
Figure 7, Profile of the Mount Cheops cirque showing the altitudinal extent of the cirque glacier.
Surveying is an important step in
understanding how the glacier is
reacting to climate change. The
main challenge in assessing the
extent of this type of glacier is
determining the margins of the ice.
It is practically impossible to see
where the glacier ends and debris
field begins because the glacier is
covered with so much rock. The cross section was measured at an area where there
was exposed ice at the margin, simplifying the task. The ice is lying up against the
inner lateral moraine, leading to an assumption that the glacier has not receded very
quickly since its last surge.
AIR PHOTOS & FALSE COLOUR SURFACE AREA COMPARISON
The air photo series is very difficult to use meaningfully for a variety of reasons,
including low resolution of the images, the small size of the study site, shadows cast
by the headwall, etc. What is clear from looking at these airphotos, however, is the
fact that the large debris fields are completely reworked between photos in the
series. This suggests active glacial processes are at work under the cover of debris,
and shows many signs associated with rock glaciers. A large feature is visible on the
lower section of debris-‐covered glacier in 1951 that is completely gone by the next
photo. Arcuate ridges, furrows and hummocky ablation moraines are clearly seen
changing through time. The extent of the glacier does not appear to have changed
drastically over the nearly 50 year period covered by these airphotos.
Figure 8, Mount Cheops cirque glacier cross-section showing approximately 11 meters of down wasting.
Figure 9, Air photo series: from left to right, 1951, 1986, 1991, 1996.
HYDROLOGICAL STUDY
Approximately 70% of the water flowing down Connaught Creek originates in the
Mount Cheops cirque. By measuring discharge above and below the Cheops input,
and the Cheops discharge itself, a detailed assessment of the origin of water in the
creek was made possible. These findings suggest that the Cheops glacier supplies a
significant amount of water into the hydrological system. Other components of this
survey included measuring the discharges of surface runoff channels along transects
below the glacier. This was done in hopes of comparing the surface runoff high on
the mountain with the discharge creek in the valley. Only a small proportion of the
water measured in the discharge creek in the valley was accounted for across the
slope, suggesting that a large amount of water is flowing downhill under the surface
of the slope. This is not surprising considering that the slope is primarily made up of
large boulders. It is also interesting to note that the combined measurements of the
Cheops drainage and the other drainage opposite Cheops combine to 1.29 m3/s,
very close to the total of 1.38 m3/s measured downstream of the confluence. This
suggests that the discharge measurement techniques used were fairly accurate.
Figure 10, Airphoto showing location drainages and survey sites.
DISCUSSION
LOCATION, HISTORY & ENVIRONMENTAL IMPACT
Mount Cheops is located in the Selkirk Range of the Columbia Mountains. The region
has been known as ‘Big Bend Country’, referring to the course of the Columbia River,
which binds the Selkirks to the east, north and west. This region was first explored
in the 19th century, during the gold rush era. Subsequently, the region was
thoroughly explored during the discovery and surveying of the first Trans-‐Canadian
railroad route. In 1881 the decision was made for the Canadian Pacific Railway
(CPR) to cross the Great Divide at Kicking Horse Pass, east of Mount Cheops and
Rogers Pass, in the Rocky Mountains. The route west from Kicking Horse Pass was
in need of discovery, and Major A.B. Rogers was the man hired to find it. The easiest
place to route the railway would have been along the Columbia River, but the ‘Big
Bend’ creates an enormous detour, over 400 km. A pass directly through the Selkirk
Range was the shortcut that was needed. Major Rogers began his search for the
shortcut from what is now Revelstoke, and traveled east through the mountains up
the Illecillewaet River. Following the river brought Major Rogers very close to the
summit of the pass, but not all the way. Mount Cheops lies just north of the
Illecillewaet River headwaters, and creates the only part of the route not along a
river. Mount Cheops has literally played a role in Canadian history, primarily as one
of the most avalanche prone areas that the transportation corridor goes through.
Mount Cheops has been the site of some of the worst disasters in Canadian
transportation history. In the railway’s first thirty years of operation, nearly 200
employees died in the area, including 62 men buried in an avalanche that cut off of
Mount Cheops in March of 1910. That experience prompted the decision to dig a
tunnel directly under the pass, averting the worst of the avalanche hazards to the
transportation route. The tunnel opened in 1916, and the summit route along the
base of Mount Cheops was abandoned until the construction of the Trans-‐Canada
Highway in 1956. The region became Glacier National Park of Canada in 1886, two
years after construction of the railway through the pass. Rogers Pass National
Historic Site is also part of the park, commemorating the importance of the
development of the trans-‐continental railway through the pass. This area would
have never become easily accessible without the development of the transportation
corridor, and therefore, we would have not had our Field School there without the
railway, this being the first significant point of the study site on Mount Cheops. Since
the Trans-‐Canada Highway opened, the region has become home to the world’s
largest active avalanche control program run by the Canadian Military. The Snow
Punchers operate 105 mm Howitzer guns, used to bomb the most prone avalanche
starting zones. The slides are started while the highway is closed to traffic, which
has greatly reduced the avalanche hazards in the area. Evidence of this activity was
found on a moraine high on the north side of Mount Cheops, where unexploded
ordinance was found during a field school excursion.
The environmental impact of the transportation corridor is clearly evident upon
exploration of the glaciated areas of the park. Black soot is clearly seen in annual
layers deposited on the ice in some places, increasing the amount of solar energy
absorbed at the surface of the ice by lowering the albedo. Imagine over a century of
locomotives burning fuel at the feet of these great mountains, 50 years of millions of
cars passing through, and image millennia of no combustion engines. It seems so
obvious now that the transportation industry has drastic impacts on the landscape.
Between 1916 and 1988 the CPR operated ‘pusher’ locomotives to help heavy trains
make it up the steep grades in the Selkirks. These ‘pushers’ added 70,000
horsepower to each train; in this respect the environmental impact is quite
shocking. Glaciers in the park are racing up the mountains, disappearing before our
eyes. When considering the effects of sublimation on the large exposed glaciers, the
input of black soot on the surface makes an enormous difference in the energy
balance of the glacial ablation.
Figure 11, A 1966 oil company advertisement bragging about their environmentally destructive capabilities.
CLIMATE CHANGE TO MICROCLIMATE
The glaciers in Glacier National Park of Canada are diminishing rapidly. Since the
first photograph of the Illecillewaet Glacier was taken in 1887, the tongue has
retreated over 2000 meters. A National Park survey approximates that large glaciers
in the park are a third of their size compared to when they were first surveyed in
1850. “Only 27% of the 99 km2 area of Glacier National Park covered by glaciers in
1850 remained by 1993” (Pelto, 2009).
Figure 12, Mount Sir Donald and the Illecillewaet Glacier, 1887 (unknown photographer) and 2009 (S.J. Rubin).
Scientists have been aware of the effects of pollutants in the atmosphere since at
least the mid 20th century. An estimate from a 1958 publication states: Our industrial civilization
has been pouring carbon
dioxide into the atmosphere
at a great rate. By the year
2000 we will have added 70
percent more carbon
dioxide to the atmosphere.
If it remained, it would have
a marked warming effect on
the earth’s climate, but most
of it would probably be
absorbed by the oceans.
Conceivably, however, it
could cause significant
melting of the great icecaps
and raise sea levels in time. (N.A.S., 1958)
This estimate was based on a solid
understanding of Earth’s energy
balance, and that the addition of
greenhouse gases into the
atmosphere causes changes in the amount of heat being trapped near Earth’s
surface. The authors understood that there would be implications for Earth’s ice,
and sea level, but their estimates were off. The population more than double in the
time since the book was written until the year 2000, and with it the demand for
fossil fuels has grown exponentially. Their estimate of a 70% increase in carbon
dioxide turned out to be more like a 300% increase, and their prediction that most
of the CO2 would be absorbed in the oceans was also quite far off, the oceans have
absorbed only 30% of atmospheric CO2 (E.I.S., 2009). Also, the authors did
acknowledge changes in atmospheric temperatures, but they did not seem to
Figure 13, Cover of a 1958 publication that predicts global warming as a result of anthropogenic changes to the atmosphere.
forecast the changes this would cause to ocean water chemistry. Acidification of the
oceans due to increased absorbed CO2 is one of the greatest problems our society is
facing today. Many sensitive oceanic ecosystems are slowly being destroyed, such as
bleaching coral reefs all over the world. Global sea level rise is also a major problem,
with the potential of creating millions of climate refugees all over planet Earth. The
focus of this paper, however, is on the effect of melting glaciers to future water
security issues. Million of people around the world depend on snowmelt and glacial
runoff for their drinking, agricultural, and industrial water supply. It is therefore
extremely important to understand how climate change is affecting snowpack and
glacial mass balance in the world’s mountainous regions. Changes in glacier run-off
have profound effects on the volume and timing of water discharged into rivers, with
important consequences for water supplies, hydro-electricity generation, maintaining
river and riparian habitats, fish populations and recreational use. This study was
conducted with the goal of helping to add to baseline knowledge of how small
microclimate glaciers are
reacting to climate change
in British Columbia.
According to the
Intergovernmental Panel
on Climate Change (IPCC),
air temperature is
considered to be the most
important factor
controlling glacier retreat.
Their studies show that
for a typical mid-‐latitude glacier, a 1oC temperature rise would have the same effect
as a 30% decrease in cloudiness and a 25% reduction in precipitation. The ICPP also
states that since the 1970s winter snow depth and spring snow cover have
decreased in Canada, particularly in the west, where air temperatures have
consistently increased. There is also evidence that the April 1st snow water
equivalent has decreased 15-‐30% since 1950 in the western mountains of North
Figure 14, Global near surface air temperature. Known as the 'Hockey Stick' graph.
America, particularly at lower elevations in spring, primarily due to warming air
temperatures rather than to changes in precipitation. These changes in snowpack
greatly affect the amount and timing of discharge, which in turn affects the entire
eco-‐system. These vulnerabilities exist along the entire course of the rivers with
headwaters in alpine areas.
CONCLUSIONS
Knowing that the Illecillewaet glacier has retreated over 2000 meters since 1887, it
is interesting to imagine the Cheops glacier barely changing in comparison. The
effects of microclimate are essential in the creation and preservation of small cirque
glaciers. Without the shade, avalanche accumulation and source rock from the north
facing headwall it would be impossible to maintain a small glacier with current
climatic conditions. The fact that there are some glaciers that do not appear to be
disappearing as fast as other glaciers in the region is intriguing, it seems timely to
consider these remaining glaciers as important sources of water in the future, but
more detailed studies and inventories are essential. While the climate change debate
wages on in politics and media, the glaciers of our alpine regions are disappearing at
an alarming rate. Glacial data and visualization is one way to end the debate;
warming temperatures have irreparable effects on our water reserves. Repeat
photography of glacial landscapes is leaving humanity with a legacy of bedrock
where there used to be ice. Resource managers can take steps in reducing the
environmental impact of transportation through the park, for example filters on the
railway tunnel exhaust systems could capture much of the soot released in the park.
Now that there is a solid understanding that increased atmospheric CO2 is warming
the planet and causing glaciers to disappear, it is time to mitigate humanity’s
pollution habit. Glacier are not a renewable resources, they have been developing
over tens of thousands of years, and we have the capabilities to destroy them within
a century.
REFERENCES
Extreme Ice Survey. <www.extremeicesurvey.org> 2009. Clark, D.H., Clark, M.M., and Gillespie, A.R. “Debris-‐Covered Glaciers in the Sierra
Nevada, California, and Their Implications for Snowline Reconstructions.” Quaternary Research, 41:139-‐153. 1994.
Coudrain, A., Francou, B, and Kundzewicz, Z.W. “Glacier Shrinkage in the Andes and Consequences for Water Resources.” Hydrlological Sciences, 50:6. December 2005.
Gardner, J. “Wenkchemna Glacier: Ablation Complex and Rock Glacier in the Canadian Rocky Mountains.” University of Waterloo, Ontario, 1978.
Graf, J.B. “Cirques as Glacier Locations.” Arc. Alpine Research, 8:79-‐90, 1976. Humlum, O. “Active Layer Thermal Regime of Three Rock Glaciers in Greenland.”
Permafrost and Periglacial Processes 8:383-‐408, 1997. Intergovernmental Panel on Climate Change. Editors: Bates, B.C., Kundzewisz, Z.W.,
Wu, S. and Palutikof, J.P. “Climate Change and Water.” 2008. National Academy of Sciences (U.S.). Planet Earth: The Mystery With 100,000 Clues.
Washington, 1958. Pelto, M. S. “North Cascade Glacier Climate Project.” Nichols College, Massachusetts.
2009. <http://www.nichols.edu/DEPARTMENTS/Glacier/glacier_retreat.htm>
Ritter, D.F., Kochel, R.C., and Miller, J.R. “Process Geomorphology, 4th Ed.” Waveland Press, Illinois, 2002.