Instructors:     Prof. George Gertner, NRES, W-503 Turner Hall, 333-9346


Prof. Bruce Hannon, Geography Dept., 220 Davenport Hall, 333-0348


Dr. Stephen Hurst, Geology Dept., 419 Nat. History Bldg., 333-0205


Dr. Seth Olsen, Atmos. Science Dept., 208 Atmos. Sci. Annex, 244-6062,


Room/Time:  22 ACES Library. Wednesdays, 5:00–8:00 p.m.


Welcome to ATMOS/GEOG 421, GEOL 481, NRES 422

"Modeling Earth and Environmental Systems”. In this course you will build and use models of climatic, hydrologic, geochemical, and human systems, explore the basic concepts of systems modeling, use models to test hypotheses, and find out about the assumptions and approximations that must be made in modeling. Your models will be constructed using the STELLA and VENSIM modeling software on PCs. STELLA and VENSIM offer an intuitive approach to modeling, so that prior experience with computer modeling is not a prerequisite for this course.


Why learn about models and modeling? First, because models have become the primary research tool in trying to understand and make predictions about earth and environmental systems. Many of you will use models in your future research. At the very least your research will be motivated by and informed by results from models, Secondly, because decision-makers use models, and their decisions affect directly how you, and everyone else, lives their lives.


Modeling is learned by doing. So, this is a course where you will spend most of your time building and using models. The goals are several:

¨     to understand how models are constructed and used, what assumptions must be made, which results are robust and which are deserving of skepticism...

¨     to grasp the fundamental systems concepts that underlie all models: fluxes and reservoirs, positive and negative feedbacks, open and closed systems...

¨     to gain basic modeling skills that can be applied in your own research...

¨     to learn about the basic principles that govern the systems we model here: the climate, the hydrologic cycle, pollution, biogeochemical cycles, and the sustainability of human activity on the earth…

¨     to learn how to calibrate and validate models and check the sensitivity of parameters.



Modeling assignments

            These will assigned and discussed in class, and class time will be provided for working on them. In general, you will work in teams on the models. Brief reports documented with models and model output will be turned in and graded.


            There will be frequent short reading assignments from Ford's book, and Meadows et al. will be covered one chapter per week, starting September 24.


To make sure everyone is keeping up with the reading and mastering key concepts, there will be weekly quizzes. These will be very short - one or two questions, taking about five minutes of class time at the beginning of class (be on time).

Final exam

The exam will test your ability to construct and analyze models similar to, but not the same as, those you have built during the course of the semester.



Your course grade will be based on four components, weighted as listed below. The success of this course depends upon your active engagement (which, of course, requires that you show up!) so we will also assess your attendance and class participation. Plus/minus grades will be assigned.


            Modeling assignments (5-6)   60 %

            Final Exam                              20

            Quizzes                                   10

Participation/Presentation        10



Modeling the Environment: An Introduction to System Dynamics Modeling of Environmental Systems, by Andrew Ford, 1999, Island Press (Required)


A "nuts and bolts" introduction to modeling dynamical environmental systems. There will be frequent reading assignments from this book throughout the term.

Use the appendices! Ford’s appendices A & B review units of measurement and some basic math. Appendix C covers the basics of using STELLA, Appendix H describes some useful special functions that are available in STELLA, Appendix E describes VENSIM, and Appendix J covers comprehensive sensitivity analysis with VENSIM.


Limits to Growth: The 30-year Update, by Donella Meadows, Jorgen Randers, and Dennis Meadows, 2004, Chelsea Green Publ. Co. (Required)

Introduces the ideas behind the World3 model, and describes what this model tells us about the future of human society. Chapters will be assigned weekly during the latter two thirds of the semester. You are not, however, required to agree with the book.



Collapse: How Societies Choose to Fail or Succeed, by Jared Diamond, 2005, Viking

A brilliant application of systems thinking, if not systems modeling, applied to the fundamental issue of what makes a human society sustainable, or not. This book is essential reading for any educated person in the 21st century.




Date          Topic                                      Principal instructor        Reading

26 Aug      Intro/STELLA tutorial                   All/Hannon

2 Sep         STELLA tools                               Hurst                       F Chap 1, App. C

9 Sep         Hydrology                                     Hurst/Hannon         F Chap 2 & 3

16 Sep       Carbon cycle                                 Hurst                       F Chap 4 & 5

23 Sep       Carbon cycle                                 Hurst                       F Chap 6 & 21

                                                                                                        MRM Chap 1

30 Sept      Carbon/Uplift                                Hurst                       MRM Chap 2

7 Oct         Climate/Atmos                              Olsen                      F Chap 10, MRM Chap 3


14 Oct       Climate/Atmos                              Olsen                      MRM Chap 4

21 Oct       Climate/Atmos                              Olsen                      F Chap 7

28 Oct       VENSIM tutorial                          Gertner                  F App. E and MRM Chap 5

4 Nov        Simple Sensitivity                         Gertner                    F Chap 15 + pp 188-208

                                                                                                        MRM Chap 6

11 Nov      Comprehensive Sensitivity            Gertner                    F Chap 18 & App. J

                                                                                                        MRM Chap 7

18 Nov      Global sustainability                      Hannon                   F Chap 22,

                                                                                                        MRM Chap 8

2 Dec         Global sustainability                      Hannon                   MRM-discussion

9 Dec         Global sustainability                      Hannon                   F Chap 16 & 17  

16 Dec       Final exam


* Readings are to be completed by the date for which they are listed

F is Ford's book; MRM is Meadows et al.


Models are due before class, the week after they are assigned. The model file and explanations are to be downloaded to the Compass site.