Case Study 4.2- Predicting Glacial Futures

During this activity, students will:

• Calculate the average rate of change in area for a set of Greenland's marine-terminating outlet glaciers between 2001 and 2009.
• Predict the area change for these glaciers for 2009–10.
• Compare the predicted area changes to the measured area changes and evaluate the accuracy of the prediction.
• Consider the ease of predicting future changes in the areas of marine-terminating outlet glaciers in Greenland.

My goals in creating this activity were to:

• Provide students with an understanding of calving of marine-terminating glaciers in Greenland as an ice loss mechanism, the prominence of this mechanism during the last decade as expressed in the data, and implications for future changes in the Greenland ice sheet.
• Facilitate students to develop skills in reading and interpreting graphs, calculating rates of change, and predicting changes in a natural system.
• Encourage students to reflect about the multiple components that may contribute to changes in a natural system and the role of uncertainty in our understanding of complex systems. Promote the consideration of the potential impacts of cryosphere changes on humans.

Educational level: introductory geology, meteorology, oceanography, or other geoscience-related course

Class size: appropriate for a variety of class sizes as this activity can be completed individually or collaboratively.

Class format: this activity is suitable for use in a lecture or lab setting or as an assignment outside of class time.

Time required: approximately 40 minutes. Faculty may choose to pare down the activity and have students work with only one data set, rather than the three that are included.

Special equipment: each student should receive a student activity sheet. It may be useful to provide students with full-page copies of figures 1, 2, and 3 so that flipping through their handout repeatedly to look at the figures is not necessary. Rulers and calculators will be helpful for calculations and drawing trend lines.

Skills or concepts that students should have already mastered before encountering the activity: Students should have a general understanding of the location of marine-terminating outlet glaciers in Greenland and their contributions to changes in the ice sheet. The resources section includes some links to time-lapse video and images of marine-terminating outlet glaciers. If this activity will be assigned as homework, it would be helpful to discuss how to calculate rates of change with students before they are given the assignment.

This activity can be used:

• as an in-class activity;
• as a cryosphere or paleoclimate lab when combined with Unit 5;
• as part of the complete Climate of Change InTeGrate module.

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Case Study 4.2 Solution Set for Instructors -- private instructor-only file

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Case Study 4.2 Images (PowerPoint 2007 (.pptx) 720kB Jul16 12)

• Regardless of whether or not students completed Case Study 4.1, it is important to discuss the different mechanisms by which ice loss occurs across the Greenland ice sheet. In Case Study 4.1, the emphasized ice loss occurred from areas between 500 and 3200 m. In Case Study 4.2, the emphasized ice loss is from marine-terminating outlet glaciers.
• The magnitude of the Greenland ice sheet and its outlet glaciers may not be meaningful to students without a bit of visualization. The Extreme Ice Survey time-lapse video clips (links to these clips are in the Resources section), especially the calving video with the US Capitol Building superimposed on the glacier for scale, may be useful in conveying sizes. Getting students thinking about a glacier's area in km² may also be challenging. You could consider doing a quick back of the envelope calculation exercise for visualization purposes. For example, you could have students calculate the approximate area of the classroom (or the student parking lot, the football field, campus footprint, etc.) in km² and estimate how many classrooms would be required to equal the area of one of the outlet glaciers in the activity.
• Students may assume that their initial calculations were incorrect if their predictions do not "match" the measured data. This is an excellent time to (a) (if they did, indeed, make an error) work with them to understand calculating rates of change and making predictions using a trend line; (b) discuss the uncertainty inherent in making predictions about complex systems like the Greenland ice sheet.

Instructors may use the questions from Case Study 4.2 to assess learning objectives.

Article: Greenland ice sheet getting darker from Climate.gov / Ohio State University.
Google Earth file: Greenland Annual Surface Melt, 1979-2007 from the NSIDC. (KMZ file)
Earth Exploration Toolbook chapter: Is Greenland Melting? GIS activity from SERC's Earth Exploration Toolbook collection.
Article: Why Is iIt Hard to Predict the Future of Ice Sheets? Vaughan, D.G., and Arthern, R., 2008, Science.

Extreme Ice Survey. 7-year time-lapse video of Alaska's Mendenhall glacier.
NOAA Arctic Report Card for Greenland
Calculating rates from The Math You Need When You Need It
Petermann glacier breakup from NASA Earth Observatory. Satellite images of the glacier before and after the calving of a massive iceberg in 2010.