Glaciers by Deborah and Brittani
We live in Juneau, Alaska, which is home to 38 glaciers flowing from the gigantic Juneau Ice Field. We love being outside, especially during our short Alaskan summers, so we decided to check out a glacier up close at the Mendenhall Glacier Visitor Center. The center has cool exhibits that explain the science behind glaciers-like the fact that a glacier is a river of ice that moves because of its own weight and that the Mendenhall Glacier receives about 100 feet of new snow each winter! We also saw some evidence, such as old photos, that the glacier has retreated in the last 30 years. That got us thinking about global warming, and we wonder: How fast are the glaciers melting?
What did we do?
We decided to take a look at the terminus-the place where the glacier meets the open water of the Mendenhall Lake. We kayaked to reach it. By studying landmarks, we could see that the terminus has indeed retreated over the years. Next we continued our research at the North Star camp, where researchers from the University of Alaska study the Mendenhall Glacier. Eric, an environmental scientist from the university, taught us how to use a steam drill to make a small hole in the ice. We inserted a long wire into the hole. By keeping data on the length of the wire, we can tell how much the glacier is moving and melting. All this work is very hi-tech. We even used a differential GPS, one that takes very exact readings, to record locations down to the centimeter!
What did we find out?
By comparing the data we collected with some that was taken 2 months prior, we know that the glacier ice can move as much as 1 foot each day! We also found that the glacier lost about 80 centimeters of depth since the last measurement. Of course, these measurements were taken in the summer months when you would expect lots of melting to take place. During the winter, when new snow falls, the glacier can grow in size again. But over the last 20 years, the glacier has been shrinking more than it has been growing.
- Compare how quickly a block of ice melts when exposed to different energy sources. Fill three small balloons with water, tie them off, and put them in a freezer overnight. The next day, set each frozen ice ball in its own bowl. Put a desk lamp with an incandesecent light bulb over one ice ball. Set up a fan to blow room air over the second ice ball. Leave the third ice ball alone, with no lamp or fan. Every 15 minutes, collect the amount of water that has melte from each ice ball, and measure the amount. Which iceball seems to be melting most quickly?
- You can study glacier flow by pouring "gak" (see recipe below) onto a model railroad landscape. Observe how the gak chooses its path, and is shaped by the terrain.
Gak Recipe: Place 2 cups white glue in a plastic bowl. Slowly add a few tablespoons liquid starch until the mixture is the consistency of putty.
Go to the DFTV Boards, and tell us about your science investigation.