Ha-Iltzuk Icefield

22 11 2012

The Ha-Iltzuk Icefield is located in the southern coast mountains of western British Columbia. The glaciers of this region are a result of the loss of ice from the Cordilleran Ice Sheet, that covered all of British Columbia and Alberta during the Pleistocene. This goes to say that the glaciers of this region are mostly affected by maritime air masses, which tells us that they receive most of their precipitation in the form of snow during the wet winter months (Oct.-Mar.) and receive little precipitation during the dry summer months.

Figure 1. In the image above the confluence where the two glaciers meet is the confluence of Silverthrone Glacier (left) and Klinaklini Glacier (right). Image of the Ha-Iltzuk Icefield courtesy of NASA Earth Observatory image of the day.

The icefield has a total area of 3600 square kilometers (1,389 square miles), making it the largest icefield in the coastal mountains south of the Alaska panhandle. The Silverthrone and Klinakilini glaciers form the two major valley glaciers of the icefield. Looking at the marginal moraines (areas of accumulating soil and rock debris) one can see how as the two glaciers meet up they form a medial moraine in the center of the confluence. These glaciers are evidence of the glacial retreat during the last 50 years. It goes without question that we have played a significant role in the change of the climate, and the increase in temperature has affected the glaciation of this region in the north western Rocky Mountains.

Glacier Mass Balance is a good way to understand the advance and retreat of glaciers, Scientists have recently used digital elevation models (DEMs) to calculate the mass balance of the Teidemann and Klinkalini glaciers of coastal British Columbia. These two glaciers are good to study because they are of relatively the same elevation, have a similar orientation and are in the same maritime climate as seen in Figure 1 and 2. In these studies change in elevation, volume and area were studied on the glaciers. The DEMs consisted of aerial photographs and satellite imagery. They found that the data was within 25 m accuracy in rural areas and 125 m in isolated areas, this is significant when interpreting their results. The DEMs for the beginning of the 20th century were composed by scanning ground and aerial photographs from the 1940’s, 60’s, 70’s and 80’s. All of the studies were conducted on 100 m elevation bands on both glaciers to provide a moderately accurate average for the glaciers.

Figure 2. The image above shows the location of the Klinaklini (Combination of Silverthrone and Klinaklini glaciers) and Tiedemann glaciers in British Columbia. PG = Prince George, V = Vancouver, BC = Bella Colla.

Another method that the scientists used to calculate mass balance was a direct method on the the glacier using a Regional Atmospheric Modeling System (RAMS). This system calculated temperature, precipitation, and evapotranspiration gradients. For each of the 100 m elevation bands these factors were estimated by the modeling system, mass balance was modeled as well using the RAMS system. From 1949 to 2009 both glaciers were found to have retreated but at significantly different rates. From the models scientists found that Klinaklini had lost an area of 5.98 square km give or take 0.57 square km, while the Tiedemann glacier had lost 42.07 square km give or take 0.29 square km for a 3 year shorter time frame. This means that the percentage of loss from the Klinaklini glacier was around 9% and the Tiedemann glacier was around 8.5% over the given time frame.

Figure 3. The above image shows the extent of the Klinkalini (top) and Tiedemann (bottom) glaciers over the study time frame 1940’s to 2000’s.

The glaciers have also lost a significant amount of volume over the 60 year time frame. Klinaklini glacier lost approximately 1.5 cubic km while the Tiedemann glacier lost approximately 20.25 cubic km from 1949-2009. Is this to say that the glacial loss is due to climate change? Results from the study have shown that on the glaciers mid-elevations accumulation has occurred causing an increase in mass of the glaciers from 2005-2009, therefore it’s questionable that human induced climate change is the number one cause for the generalized loss of glacial ice within the region. The scientists have modeled the beginning of the 21st century in this study, but predicting the future is difficult to do as the population continues to grow at a rapid rate and more and more countries are trying to achieve a “western” lifestyle. If the glaciers continue to melt at the rate they are currently it would be expected to raise the oceans by a significant amount.

References

Figure 1 ~ NASA Earth Observatory

Other Figures

Tennant, Christina, Brian Menounos, Bruce Ainslie, Joseph Shea, and Peter Jackson. “Comparison of Modeled and Geodetically-derived Glacier Mass Balance for Tiedemann and Klinaklini Glaciers, Southern Coast Mountains, British Columbia, Canada.” Comparison of Modeled and Geodetically-derived Glacier Mass Balance for Tiedemann and Klinaklini Glaciers, Southern Coast Mountains, British Columbia, Canada 82-83 (2012): 74-85. Science Direct. Web. 12 Nov. 2012. <http://0-www.sciencedirect.com.skyline.ucdenver.edu/science/article/pii/S0921818111002049&gt;.

Background Information ~ (Size, location, ect.)

http://earth.jsc.nasa.gov/EarthObservatory/HeiltskukIcefieldBritishColumbia.htm

Tennant, Christina, Brian Menounos, Bruce Ainslie, Joseph Shea, and Peter Jackson. “Comparison of Modeled and Geodetically-derived Glacier Mass Balance for Tiedemann and Klinaklini Glaciers, Southern Coast Mountains, British Columbia, Canada.” Comparison of Modeled and Geodetically-derived Glacier Mass Balance for Tiedemann and Klinaklini Glaciers, Southern Coast Mountains, British Columbia, Canada 82-83 (2012): 74-85. Science Direct. Web. 12 Nov. 2012. <http://0-www.sciencedirect.com.skyline.ucdenver.edu/science/article/pii/S0921818111002049&gt;.

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Holocene Glacier Fluctuations

19 11 2012

During the Wisconsonin glacial advance, which occurred during the late Pleistocene and early Holocene (approximately 110-10 thousand years ago) the Cordilleran Ice Sheet covered what is now an exposed high elevation, alpine environment in the northwestern Canadian Rockies. It has been noted that there was a retreat that occurred during the early Holocene, but then a significant advance approximately 9-6 thousand years ago. Scientists have noted this advance by cirque moraines and glacier rock deposits in many places that are covered by the tephra. Brian Luckman and Gerald Osborn have noted the crowfoot advance in by these deposits in Jasper and Banff national parks.

Figure 1. The Storm Mountain Cirque in Banff national park where a Crowfoot moraine is seen on the right being partially tree covered.

In recent years (post-1900) studies of the glaciers in the Canadian Rockies has been mostly compiled by photos as well as mass-balance data provided by Mokievsky-Zubok compiled in the 1980’s. Photographs from 1880-1920 show glacier fronts close to their Little Ice Age maximums (defined by moraine features that have been deposited by the glacier fronts). From 1920 to 1950 glaciers in the region had seen a slight retreat as noted by mass balance models as well as ground and aerial photography. However, after this retreat there was a stabilization from the late 1950’s to the 1970’s. During the 1970’s many glaciers remained stable in this region, and some even saw advances. This data was provided by Brian Luckman’s study of 31 glaciers in the Premier Range, of the 31 studied 90% were stable and some of which showed the advance. There was also glaciers in the coast mountains that were found to show advance, most likely due to lower summer temperatures during this decade.

References

Images and Information

Osborn, Gerald, and Brian H. Luckman. “Holocene Glacier Fluctuations in the Canadian Cordillera (Alberta and British Columbia).” Holocene Glacier Fluctuations in the Canadian Cordillera (Alberta and British Columbia) 7.2 (1988): 115-28. Science Direct. Web. <http://0-www.sciencedirect.com.skyline.ucdenver.edu/science/article/pii/0277379188900029&gt;





The Little Ice Age

17 11 2012

The Little Ice Age was the time period to follow the midevil warming period of the start of the last millennium. There was a significant cooling of the climate that caused this Little Ice Age where glaciers in the northwestern Canadian Rockies extended in the proglacial environment from approximately 1400-1600 A.D.

Figure 1. The graph above represents a simplistic idea of temperature variance of the Canadian Rockies over the last 1000 years. Note where the Midevil warming period begins and ends as well as the years Where the Little Ice Age begins.

Glaciers reached their maximum extent during the time frame of the Little Ice Age and show this evidence by moraines that are one of the most dominant landforms of the Canadian Rockies.  Dating these moraines has proven to be extremely difficult as the only way to date the fabric above tree line is through lichenonometry which is the study of lichens and lithobionts that grow on the surface of rocks within the moraines.  However, many of the glacier moraines are below tree line which allows scientists to study the dendrochronolgy of the moraines, or in layman’s terms the study of trees that are growing in post-glacial fields. Using this dating method the oldest tree along the edge of the glacial path is studied to determine how long it was before the retreat, also dead material that has been preserved in the glaciers is often carbon dated to show the age of morainal material. Many of the glaciers in the region can be studied over the last 100 years or so through aerial and ground photography. There are some errors within both dating methods of morainal material that have been accounted for approximately ±5 years.

Figure 2. The image above shows the Athabasica Glacier in the summer of 1917 and September of 1986. There is approximately a 1.5km retreat over the 70 year period, as well as a proglacial lake that was formed in the glacier valley due to the runoff of melt water from the glacier.

Many of the glacier forefields contain moraines that fall between the maximum extent of the Little Ice Age and the current glacier fronts. These moraines are mostly from the time frame between the late 1800’s and early 1900’s. The glacier fronts in the early 1900’s are very close to the moraines that represent the Little Ice Age maximum extent. The highest recessional rates were recorded in the early decades of the 1900’s with a slow downturn as some glaciers advanced slightly between 1950 and 1970. Over the last few decades we have seen another peak in recession of these glaciers, most likely due to climate change.

References

Images and Information

Luckman, Brian H. “The Little Ice Age in the Canadian Rockies.” Geomorphology 32.3-4 (2000): 357-84. Science Direct. Web. 15 Nov. 2012. <http://0-www.sciencedirect.com.skyline.ucdenver.edu/science/article/pii/S0169555X9900104X#&gt;.





The “Neoglacial” Period

14 11 2012

The image above shows the estimated extent of the Cordilleran Ice Sheet approximately 17 thousand years ago. As one can see parts of the Ice Sheet extended into northern parts of Washington and Montana.

After the late Pleistocene glacial retreat there was a period during the early Holocene where there was glacial advance in the Canadian Rockies that is referred to as the neoglacial period by scientists. This neoglacial period occurred approximately 7.5-5 thousand years ago and resulted in the advance of some glaciers within the southern coast mountains of British Columbia and the southern mountains of Alberta. In the recent retreat of these glaciers stumps have been revealed that have been dated 6.95-5.62 thousand years ago. Radiocarbon dating of these stumps and detrital wood have proven this mid-Holocene glacial expansion that scientists refer to as the Garibaldi Phase. They chose to use the word phase rather than advance because there was no evidence of glacial retreat during this time period.

Figure 1. The image above shows the study area for the stumps and detrital wood that was found to show the glacial expansion during the Garibaldi Phase. There is significant evidence in this region to explain how during the early Holocene glaciers within the Cordilleran Ice Sheet began to advance slightly after their slight retreat in the late Pleistocene.

This neoglacial phase occurred prior  to what is known as the Little Ice Age which describes glacial advances in the last millennium, with a focus on advances during the 12th and 13th centuries. Most of the neoglacial period occurred before a slight warming of the climate during the early years of the last millennium that is known as the midevil warming period. Glaciers of the Little Ice Age reached their maximum extents during the 17th-19th centuries and began their retreat during the early 20th century.

Figure 1. The image above shows one of the stumps that was radiocarbon dated to be from the late neoglacial period. Five other stumps were found within close proximity to this one dating back to the same time period.

Figure 3. The image above shows till fabric from the Tiedemann Glacier that has been studied and dated back to the neoglacial period approximately 13.5 thousand years ago.

It has been estimated from reports on 120 glaciers in the Canadian Rockies that there was a twenty-five percent loss of ice from the Little Ice Age to the 1970’s. Prior to the Little Ice Age there was a period of warming that occurred in the late neoglacial period that some scientists refer to as the midevil warming period as it occurred from the 11th to the 15th centuries.

References

Images & Information

Menounos, Brian, Gerald Osborn, John J. Clague, and Brian H. Luckman. “Latest Pleistocene and Holocene Glacier Fluctuations in Western Canada.” Quaternary Science Reviews 28.21-22 (2009): 2049-074. Science Direct. Web. 10 Nov. 2012. <http://0-www.sciencedirect.com.skyline.ucdenver.edu/science/article/pii/S0277379108002977#&gt;.





Cordilleran Ice Sheet During the late Pleistocene

7 11 2012

The Cordilleran Ice Sheet during the Pleistocene reached down into the Northern parts of Washington and Montana over 20,000 years ago, but started to retreat near the end of the Pleistocene era. During the late Pleistocene (approximately 16,000 – 11,700 years ago) the climate of the region started to see fluctuations, causing the Cordilleran Ice Sheet to began its retreat in some areas while other areas were still advancing. The Ice Sheet during this time frame covers all of a high alpine environment that is exposed today.

Figure 1. The image above shows the direction of ice flow on the Cordilleran Ice Sheet during the Pleistocene era. The portion of ice that reaches the southern most point in this image is known as the Puget Lobe.

Roughly 17 thousand to 16.5 thousand years ago what is known as the Puget Lobe had reached its southern most point in what is now Olympia, Washington. Lasting for roughly 500 years the ice began to retreat North. It wasn’t until about 14.5 thousand years ago that this retreat came to a halt and glacier advance began to take course again. Scientists have suggested that this glacial advance begun the process of morainal deposition  around 13.5 thousand years ago, however no absolute dating methods have been done to prove this.

References

Images 

Figure 1 – http://www.sfu.ca/~qgrc/BC_icesheet.jpg

Information

Menounos, Brian, Gerald Osborn, John J. Clague, and Brian H. Luckman. “Latest Pleistocene and Holocene Glacier Fluctuations in Western Canada.” Quaternary Science Reviews 28.21-22 (2009): 2049-074. Science Direct. Web. 10 Nov. 2012. <http://0-www.sciencedirect.com.skyline.ucdenver.edu/science/article/pii/S0277379108002977#&gt;.





Introduction

1 11 2012

Hello all,

To all who view my blog here is a little info about me and this blog, my name is Paul Schaffnit and I am currently attending the University of Colorado at Denver, studying Geography. This blog will take a look at the changes of the Cordilleran Ice Sheet, several glaciers of the Canadian Rockies and the glaciers within British Columbia and Alberta, Canada from the Pleistocene (approximately 2.5 million years ago – 11,700 years ago) to the Holocene (approximately 12,000 years ago – present). Climate change has played a big role on changes in glaciation from the Pleistocene to the Holocene which has affected things such as sea level rises and many other climactic variations on this planet. I will touch on many of these topics throughout the blog entries to follow.