Controversies in the Earth Sciences

Reading assignment: Alaskan glaciers and Antarctic ice sheets

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How much water is in a cubic kilometer of water?

The volumes discussed in this studies like these (for example, amount of ice lost, amount of meltwater produced, etc.) are given in cubic kilometers. Do you have any sense about how much water is in a cubic kilometer? Here's a little estimation that puts this into perspective (and a close-captioned version)


The contribution of land glacier melting to global sea level rise has been explored in a recent study of Alaskan glaciers. In this study, airborne laser altimetry was used to determine the mass and thickness of over fifty glaciers. This method is a huge improvement over previous studies that have used complicated and imprecise mass-balance calculations to estimate the rate of glacial melting. The results of this new study show that Alaskan glaciers contribute more meltwater than was previously thought and are losing mass faster than was previously thought. When you read these papers, think about how the results of this study will be incorporated into global climate models.

Then, read a paper that is about climate modeling in which researchers construct a model that does a better job of fitting the sea level and temperatures of the past than has previously been accomplished. The key was adding in warming ocean currents, a warm atmosphere, and a chain reaction of collapsing ice shelves.

As usual, for the Alaskan glaciers paper I recommend reading the accompanying Perspective (Meier and Dyurgerov, 2002) first, then reading the scientific paper (Arendt et al., 2002). For the modeling work, I recommend reading the accompanying News Focus first (Tollefson, 2016) and then the scientific paper (DeConto and Pollard, 2016).


  • Meier, M. F., & Dyurgerov, M. B. (2002). How Alaska affects the world. Science, 297(5580), 350.
  • Arendt, A. A., Echelmeyer, K. A., Harrison, W. D., Lingle, C. S., & Valentine, V. B. (2002). Rapid wastage of Alaska glaciers and their contribution to rising sea level. Science, 297(5580), 382


  • Tollefson, J. (2016). Trigger seen for Antarctic collapse. Nature, 531, 562.
  • DeConto, R.M. and D. Pollard (2016). Contribution of Antarctica to past and future sea-level rise. Nature, 531, 591.

Questions for discussion:

  • What are the specific causes of sea level rise and how are these causes measured?
  • What factors contribute to predictions of future sea level rise? How does the new data detailed in Arendt et al.'s study impact sea level rise calculations? How does the new model in DeConto and Pollard's study impact sea level rise predictions?
  • What are the difficulties involved in making measurements of ice volume? What are the different methods used and how do they work?
  • How is past sea level reconstructed?

Participating in the discussion

The discussion component of this activity will take place over Week 1 of this lesson and will require you to participate multiple times over that period.

  1. Enter the "Alaskan Glaciers and Antarctic Icepapers" discussion forum.
  2. You will see the questions above already there
  3. Respond to a question that hasn't already been chosen by another student. If all questions have already been addressed, then select a question where you can further the discussion and post there.
  4. Return to the discussion periodically to read your classmates' postings and to respond by asking for clarification, asking a follow-up question, expanding on what has already been said, etc.

Grading criteria

You will be graded on the quality of your participation. Please see the rubric for teaching/learning discussions.