Module 9 - The Terrestrial Cryosphere

Explain:
Right off the bat I want to get some definitions down that I think are important to know... 

• ice age/glacial age - a generic geologic term related to a long-term reduction of global temperatures and the growth of continental ice sheets.
• glacial periods - colloquially referred to as ice ages, these are periods within glacial ages marked with even colder temperatures than the overall glacial age.  During this time, continental ice grows covering more of land with ice.
• interglacial periods - periods of time, still within a glacial age, that is marked by above average temperatures.  Continental ice may fluctuate during this period, but because of the large amount of continental ice still around, it is still within the glacial age.

I was not familiar with these differences and found them necessary to discussions later in the module. 

After following the Wikipedia trail about glacial ages I got stuck on the collapse of the Larsen B Ice Shelf mentioned in one of the TD videos.  From there I went to back to Wikipedia.  There I found that the "B" in the shelf's name differentiates it from the other two Larsen shelves - "A" (the smallest), and "C" (the largest).  What is shocking is that the three Larsen shelves were stable for thousands of years (B, the one that collapsed for the previous 12,000 years).  In a matter of weeks, Larsen B calved and disintegrated into the sea.

Explore:
I was quite interested in those three shelves, so I went a bit further in researching them.  I think that this would make a very interesting exploration with my class as well, because it combined the four resources in the class that I find myself using a lot - the class blog, Teachers Domain, Wikipedia, and Google Earth.

The orange represents the missing ice shelves

In Google Earth I spent some time looking at the area of Antarctica that the shelves are located on.  The Larsen Ice Shelf runs along the eastern edge of the Antarctic Peninsula. 

Of the three shelves, only the largest, C, remains.  Larsen A collapsed in 1995 and Larsen B disintegrated in 2002.  After looking at recent satellite images in Google Earth I found a button there that I wasn't aware existed - one that allowed me to look at historic images.  Amazing.  I could follow the collapse of Larsen B over those critical weeks in 2002.  I captured those images below and created a little movie.



Evaluate:
I enjoyed this module.  What struck me over and over was that in all the talk about climate and geologic time, this area of science stuck out as being able to buck all that thought.  Of course, terrestrial cryosphere systems take place on those time scales, but they are also visible in human lifetimes, and as the Larsen Shelf shows - even months.  These are important things to keep in mind.  Global warming may not raise sea levels to historic levels (tens of meters) in my lifetime.  Global temperatures may not rise high enough to turn my home state of Minnesota into a tropical jungle.  Polar bears may not go extinct.  But I don't want to find out that these predictions are wrong.

There seem to be so many examples in these past two modules about catastrophic "burps" as one scientist called them.  The release of methane and CO2 from thawing permafrost.  The change of oceanic currents as melting sea ice and continental ice change ocean temperatures and open sea routes.  Small things that will bring about monumental change.

I guess time will tell.

Three Colleagues:
I visited the following classmates' blogs... 

• Dan Adair's posts were very nice to read and full of images and links and all that good stuff.  I was interested is his intro to the module with a discussion about Captain Vancouver and his explorations around the area.  
•  Alicia's Science Explorations blog was also a good read.  I enjoyed reading the facts she learned about the cryosphere in a prelearning activity - it was nice because I too felt the need to get some prelearning in prior to starting the module.
• Last stop was Amy's Explore Alaska Blog.  She was struck by the $35 million permafrost damage figure mentioned in one of the TD videos.  It is an alarming amount of money.  In my village I have seen the result of melting permafrost as our school was recently reinforced because it was sinking.  These fixes are incredibly pricey, especially in rural regions where getting heavy machinery in an out is so complicated.