The Critical Zone

System Modeling


The goal of this final lesson is for you to create your own qualitative Critical Zone model, recognizing that the Critical Zone is a very complex system with human and natural components.

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One example of an Earth system model addressing some of the processes relevant to global warming.
Source: Integrated Earth System Model Development Group



For this assignment, you may do your work by hand (e.g., pen/pencil and paper), in a word processing document, or using a drawing program of your choice. No matter what you choose, your work must be submitted in Word (.doc) or PDF (.pdf) format so I can open it.

  1. To solidify your concept of the Critical Zone as a system, please read the following article, located in Library Reserves.
    • Brantley, S. L., Goldhaber, M. B., & Ragnarsdottir, K. V. (2007). Crossing disciplines and scales to understand the critical zone. Elements, 3(5), 307–14.
  2. While I outlined some of the most basic concepts of system modeling in the introduction to this lesson, more knowledge of approaches to system modeling is required to accomplish your model, so please read pages 1–19 in "System Behavior and System Modeling."
    • As you read this, be aware that you will next read through a handful more documents describing some of the specifics of human influences to and alterations of the Critical Zone.
    • Skip the preface and any mentions of the Stella II computer model. Also skip the exercises on pp. 6, 10, and 19, unless you feel you need the practice—but do not hand these in to me expecting a grade!
    • Focus in on the text that describes: (1) the identification of system components and interactions of your system with other systems; (2) the identification of interactions between the components of your system; and, (3) qualitative and quantitative modeling.
  3. When you are ready to begin creating your model, work through the exercise described beginning on p. 2 of "System Behavior and System Modeling," using an outline format, adding arrows, labels, etc., as you progress deeper into your model. Feel free to work through their example for atmospheric carbon dioxide as a "thought" exercise if you choose, but the point of your effort should be to outline your own qualitative system definition of the Critical Zone.
  4. Continue through the exercise by building a conceptual model with a stylized drawing (p. 5). The drawing should include reservoirs, flows, valves, branches and interconnections where appropriate (p. 11).
  5. Extra credit: Can you plug numbers or equations into your conceptual model to create a quantitative model? If so, can you assess potential perturbations or forcings and the future effect of these on the global Critical Zone or Critical Zone at your study site?
  6. Scan or save your document as either a Microsoft Word or PDF file in the following format:

    L12_cz_system_model_AccessAccountID_LastName.doc (or .pdf)

    For example, student Elvis Aaron Presley's file would be named "L12_cz_system_model_AccessAccountID_LastName.doc"—this naming convention is important, as it will help me make sure I match each submission up with the right student!

Submitting your work

Upload your paper to the "Lesson 12 - CZ System Model" dropbox (in the lesson under the Modules tab) by the due date indicated on our Canvas calendar.

Grading Criteria

You will be graded on the quality of your writing. You should not simply write responses to the questions and submit them to me. Instead plan on writing a short stand-alone paragraph (or page or whatever you decide is necessary considering any constraints I might have placed on you) so that anyone can read what you've written and understood it. You should strive to be specific and complete in responding to the questions. Your answers should be analytic, thoughtful and insightful, and should provide an insightful connection between ideas. The writing should be tight and crisp with varied sentence structure and a serious, professional tone.

Check this out . . .

The activity entitled "Exploring environmental change" provides an additional or optional mechanism for classroom introduction of the basic concepts of modeling an Earth system.