Environmental Systems
Modelling Prompt: Tragedy of the Commons
After completing this worksheet you should be able to derive system dynamic principles from a given (simple) model.
Software, data and literature you need for this modelling prompt:
Tragedy of the Commons
“The population problem has no technical solution; it requires a fundamental extension in morality.” Hardin (1968)
This sentence is the entire abstract of Hardin's Science publication from 1968 in which he introduced the tragedy of the commons principle. In short, commons are shared resources which can be used by anyone. The tragedy relies in the economic interest of each individual who wants to maximize its gain.
Please read Hardin (1968) now.
A model on the tragedy of the commons
In this modelling prompt, we start with a given model and derive the underlying system dynamics from the graphical representation. For this case, we use the model EZ417 from Bossel (2004b).
Please run the model using the standard settings. Describe the dynamics of the variables renewable resources, production capital, annual production and annual net profit . How is the tragedy of the commons expressed by the changes of these variables?
Please derive a system description from the stock and flow model EZ417 and explain the functional dependencies leading to the tragedy of the commons.
- What stocks are used in the model?
- What constants are used in the model?
- What is the relationship between the stocks and their immediate inflow or outflow relationships (e.g. start with accumulated net profit but only follow the input relations to a “depth” of two, i.e. annual net profit < revenue < annual production).
Once you have finished your inverse modelling you should have noticed, that the relation between actual regeneration rate, PRODUCTION GOAL and RESOURCE PRICE is crucial for the tragedy to happen.