NetLogo User Community Models

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WHAT IS IT?

This model is about the prisoners dilemma in worldwide environmental problems. Everybody has excess to the services that the environment brings but at the same time shares in the environmental burdens that are caused by our activities. The prisoners dilemma tells us that mitigating environmental problems will cost us money as individuals and at the same time gives benefits to not only ourselves but also to our neighbours. The most beneficial situation in coping with environmental problems is not to take measures to improve the environmental situation, but let your neighbours do so.
This model demonstrates the negotiation process of countries dealing with a common environmental problem: the sun is dark. The dots in this model can be seen as individual countries that are situated in a network with other countries. Some countries are willing to take measures to brighten the sun, others are not. Negotiating with unwilling countries should convince them of the need to join an environmental program to improve the environmental quality. The more countries joining the program, the brighter the sun gets.

HOW IT WORKS

Every step in time (tick), willing countries (green dots) try to convince the unwilling countries (red dots) to join the environmental program. The success of this negotiation depends on the:
- Number of countries joining the negotiation network.
- Number of positive starters; the countries joining the program from the start.
- The connections between different countries; structure of the network. In reality not all countries will join international negotiations, and some countries will have more connections with each other than others.
- The willingness to cooperate; in reality this is the result of a complex political process for every individual country. In this model it is simply described by the cooperativity chance, given as a percentage for 0-100.
These aspects can be changed by the different model sliders. This is a one-way model, what means that once a country became cooperative, there is no way back. The end-result of a model-run therefore always is an environmental situation in which the sun is bright. This is where the model stops.

The model also keeps track of the individual budget of the different countries. Taking measures costs the countries money, environmental gains however are for everybody and these therefore will increases all countries budget. This is shown by the label attached to each country.

HOW TO USE IT

The first two sliders NUMBER-OF-COUNTRIES and AVERAGE-COUNTRY-CONNECTION determine how the network is set with a certain degree of randomness.
The POSITIVE-STARTERS slider gives the number of countries that are cooperating in the environmental program from the beginning.
The COOPERATIVITY slider gives the chance that unwilling countries become cooperative to join the environmental program. This is stated as a percentage.
Using those sliders will set the starting conditions of the negotiation process.
Press STETUP to create the network of countries.
Press GO to start the negotiation process start at 1 tick at a time. Press GO-infinitive to let the negotiation process run until the environmental problem is solved.
The TOTAL-POSITIVE monitor shows the economic value of the improved environmental condition, which equals the budget of unwilling (red) countries, also called 'free-riders'
The BUDGET-COOPERATIVES monitor shows the budget of the countries that join the environmental program (costs for taking environmental measures + environmental gains)

THINGS TO NOTICE

The model shows that the budget of non-cooperative countries is always higher than of cooperative countries. It therefore is more beneficial to do nothing and wait for your neighbours to act. However, if everybody thinks like this, all countries will live in the dark.

THINGS TO TRY

Running the model at different slider values can show more and less effective ways to accelerate the environmental problem solving process. With behaviour-space this can be done in a systematic way.

EXTENDING THE MODEL

This model can be extended by adapting it more to reality:
-different type of network setting that resembles the world negotiation situation between countries.
-differentiation between countries: size, costs, measures, cooperativity etc. This can for instance be done in groups: western, non-western etc.

RELATED MODELS

Netlogo has a few more models based on the prisoners dilemma.
The structure of this model was based on the "Virus on a Network" model by Uri Wilensky.

CREDITS AND REFERENCES