Module IX - Terrestrial Cryosphere

by Kris Owens

Explain: What new learning or reflections have you taken from this module?

My exploration of this module began with learning about the Huna Tlingit. The contributions their history and culture has been able to make to knowledge of the Glacier Bay region is apparent.  They are able to describe how Glacier Bay has changed over hundreds of years, with information regarding climate, glacier activity, and the people who live there. Their culture has been affected by changes, such as having to move from Glacier Bay, to the north shore of Chichagof Island on Icy Strait. 

I learned that in the past, Glacier Bay was a single ice sheet called the Grand Pacific Glacier.  At one point it was 4,000 feet (1,200 m) thick and about 20 miles (32 km) in width. Over the last 200 years it has retreated by 65 miles (105 km) to the head of the bay at Tarr Inlet, leaving 20 separate glaciers in its trail.  It was interesting to read that John Muir visited the bay in the late 1800's. 

The TD movie, Changing Arctic Landscape explained that like sea ice, glaciers reflect heat back into the atmosphere.  Instead of being reflected, the heat is absorbed, with the consequence that their loss may accelerate climate change. 

The segments on permafrost were also very enlightening.  Melting permafrost allows more water to be absorbed and opens up channels leading to disappearing lakes and ponds.  Trapped gases are also released into the atmosphere - a cycle that leads to faster melt of permafrost, much as with glaciers and melting sea-ice. As climate changes, native flora and fauna are affected. New species encroach, weakened plants are susceptible to insects such as spruce bark beetle.  Insect infestations such as the spruce bark beetle also lead to increased tinder, and the possibility of more devastating forest fires.

Thawing permafrost also moves water from above ground storage to below ground storage.  As permafrost thaws, water percolates through the soil to aquifers below, draining ponds and lakes.The effects of this change are complex, and impact the ecosystem, weather, and climate.

Thawing permafrost creates habitat changes for migratory birds, fish, and other wildlife.  In addition, as water is removed from the surface, the danger of forest fires increases. Because evaporation from lakes creates clouds and rain, scientists assert that the loss of lakes may also affect local weather.

Melting permafrost may also accelerate global warming by releasing greenhouse gases into the atmosphere. Vast amounts of organic carbon are  frozen in the soil. In drier areas, carbon takes the form of carbon dioxide, and in wetter ones, methane.Methane's capacity to warm the atmosphere is even greater than that of carbon dioxide.

Google Earth pictures of an area that I have canoed in over the last 16 years. 

We have wondered about the shrinking lakes in this area

The TD video Losing Permafrost in Alaska presented some interesting statistics related to the thawing of permafrost.  For example, repairing damage caused by melting permafrost costs a whopping $35,000,000 a year!  Another interesting statistic is that temperatures in interior Alaska are rising at a rate 10 times faster than the rest of the world. 

The definition of Earth’s cryosphere and the role it plays in terms of Earth’s climate, was also clarified in this module.  The cryosphere is the frozen areas of Earth's surface, including snow, glaciers, ice sheets, ice shelves, icebergs, sea ice, and permafrost .  Permafrost is defined as land that is below 0 degrees Celsius for two or more years.

Sea ice plays an important role and acts as an insulating barrier, reducing the transfer of moisture and heat from the ocean to the air, which affects atmospheric circulation. In addition, freezing and melting of sea ice affect the salinity of the water and influence ocean circulation patterns.

The TD movie Earth's Cryosphere presents startling information about the cryosphere and changes that are taking place.  I learned that the ice of Antarctica contains 70% of the worlds fresh water, while at the same time is one of the driest places in the world. 

Glaciers and ice-streams carry ice from the interior of the continent to the edges.  There, glaciers converge, forming huge floating ice shelves.  One of largest, the Ross Ice shelf, is several hundred meters thick, about 497 miles across, and 90% submerged.  How quickly change can take place, was also made evident, with ice shelves such as the Larson B, which after 12,000 years, collapsed in just 5 weeks. 

The TD Movie Climate Change pointed out that climate is also constantly changing, and that these changes are not always over long periods of time.  In fact, research conducted over the last 20 years or so describes dramatic shifts in Earth’s climate, that occurred over a period of a decade or less, rather than over thousands of years.

The ice core projects taking place in Greenland are fascinating.  The Greenland ice sheet is over 2 miles deep with ice at the bottom formed over 250,000 years ago! Layers of ice analyzed from Greenland ice cores reveal the rapid onset of ice age conditions. They show average continental surface temperatures rising and falling dramatically in just a few years.

My understanding of Earth’s Ice Ages was also vague, and grew as I progressed through this module. I learned that ice ages are set in motion by gradual changes in the Earth's tilt, rotation, and orbit over thousands of years.  Other factors, such as the composition of the atmosphere, Milankovitch cycles, continental position, and ocean currents, also play a role.  It is amazing to consider that during the last glacial maximum, about 18,000 years ago, it would have been possible to walk from Alaska to New York, on ice! 

The Ice Sages section of this module introduced several glacial deposit terms that I had not encountered previously.  These included -

• eskers: steep sided ridges of gravel/sand, possibly caused by streams running under stagnant 
• icekames: stratified drift builds up low steep hills
• varves:  alternating thin sedimentary beds (coarse and fine) of a pro-glacial lake.  Summer conditions deposit more and coarser material and those of the winter, less and finer. 
• drumlins: smooth elongated hills composed of till.

While I had heard of pingos, I had not seen anything like the pingo and polygon wedge ice photo at the  pingo description on Wikipedia.  As I explored this section, I learned that ice wedges are of three types: active (still forming) inactive (not forming, still filled with ice) and casts (no longer have ice in them, instead sediment/dirt filled).   Ice wedge casts can be used to determine climate from hundreds of thousands of years ago.

Meltin Pingo and Polygon Web Ice - Wikipedia

The Tunnel Man videos are fantastic and would definitely engage students.  They are a fun way to learn about permafrost and how ice wedges form.  The implications of building roads and buildings over permafrost were also brought out.

Extend: How might you use this week’ information and resources in your lessons?

One of our themes at Fireweed is “Cycles.”  Previously, we have taken a close look at the water cycle as a main focus in science.  As I worked through this module, I realized that there are many related ideas we could be exploring. I will definitely be using both the  A Drop in the Bucket and A Thousand Snowflakes activities in the future.  These were enlightening for me and will be a great attention grabber for students.  

Several of the websites highlighted in this module offer great potential as resources.  While at the site, Glacier and Landscape Change in Response to Changing Climate, I checked out the USGS education links.  Here I found  a variety of lessons and useful tools.  Terraweb for kids looks especially interesting.

As I explored, I landed at a site called Earthshots: Satellite Images of Envirnomental Change.  Here, you find an interactive map to explore environmental change around the world.  Clicking on Alaska’s link brings you to  (Clickable map) (Image) satellite photos and a description of the 1986 event during which Hubbard Glacier surged, creating an ice dam that blocked off a fjord.            

The site Alaska Climate Summaries also looks very useful.  The site provides monthly data from 1932 - 2005, including  maximum temperatures, minimum temperatures, precipitation, snowfall, and snow depth.  The site reveals changes in climate, and provides plenty of data for graphing and analyzing with students.

There were also several resources that could be used when learning about glaciers.  One of these, Documenting Global Change - Teacher’s Domain - provides an intriguing to look at “then and now photos” of different glaciers in our state and includes thought-provoking discussion questions.

An idea that always comes up when studying glaciers is that they are like rivers of ice.  Examples such as the Jakobshavn Glacier, flowing at 113 feet per day, could really reveal this idea  to students. It is amazing that 20 million tons of icebergs are cast off each day by this glacier, and are responsible for 4% of global sea-level rise in our times.  

The Mendenhall Glacier time lapse photography from Extreme Ice Surveys is also a great way to show kids the idea that glaciers flow.  Showing the footage in both directions makes it even more dramatic.

Students would also enjoy learning about how glaciers change over time, through exploration of the repeat photography found at Glacier and Landscape Change in Response to Changing Climate.  The following 3 photos of Toboggan Glacier (Prince William Sound) were taken in 1905, 2000, and 2008.  

 

Credit: U.S. Geological Survey

Department of the Interior/USGS

U.S. Geological Survey/photos by Bruce F. Molnia

Evaluate: How useful, insightful or relevant are this module’s information and resources?

A great deal of this module provided information that explains observations we make in our own environments.  For example, our students enjoy that they can light off the methane bubbles found in our local ice-skating lake (Beluga Lake, Homer).

As I watched the You-Tube videos of methane burining, I also stumbled into a very exciting video about glacier surfing in Alaska. This video shows glacier calving and a risk-taking surfer riding the wave generated.  While this is a fun one to watch, you would want the sound off if sharing it with students (questionable language).  

The melting of permafrost and the implications are also very relevant to our lives. The TD movie Melting Permafrost, makes the impact and ‘here-and-nowness’ of the problems associated with melting permafrost very clear. 

One of the impacts of melting permafrost is that water percolates through the soil to aquifers below, draining the lakes.  I wonder if the lowering of lake levels in areas where I canoe each summer are due to melting permafrost, or other factors.  The changing waterlines of ponds and lakes in this area can be seen  in this Google Earth picture.   

The TD movieClimate Change will also be useful when my students participate in Journey North’s  Mystery Class project.   Each year, one of the mystery sites is invariably a scientific research station, such as in Antarctica or Greenland.  Last year’s site was located in Greenland and was carrying out ice-core studies.  We have done some exploration on this topic and this video provides an additional opportunity for learning about current research. 

Three Colleagues

Eric Ellifson - I enjoyed the links  Eric provided in his blog on module VII.  It was interesting to take a look at the impact of owning pets and the comparison to owning an SUV at the provided link and reading the preview of the article “How Green is your Pet?” at the New Scientist magazine link. 

Dominic (Nick) Pader- Dominic makes some interesting observations about his students and ideas that go beyond their immediate environment, such as our greater universe.  I also enjoyed the “Extend” section of his blog, an appreciated the photo of liquid CO2 sitting 3000 feet down in the bottom of the ocean.  He also mentions the usefulness of the “Element Song” and want to share a video my students recently enjoyed while exploring this topic.

They Might be Giants - Meet the Elements 

Windsor Demore- As I read Windsor’s recent blog I became interested in the curriculum spiral chart he refers to.  Clicking that link led to a great source of online resources and lessons at the ANKN website.