Using stella models to explore the dynamics of earth systems: Experimenting with earth's climate system using a simple computer model

Described herein is a simple computer model that enables undergraduate students to learn some interesting and fundamental lessons about the dynamics of Earth's climate system. This model uses the program STELLA to treat the climate system as just two boxes (reservoirs) that represent the thermal energy stored in the atmosphere and the Earth's surface (a combination of land and water). These reservoirs are linked by a small number of flows that transfer energy from one reservoir to another as well as to and from outer space. The simple nature of this model means that it cannot provide information about the spatial variations in temperature. The model developed here incorporates real values for the components of the system and thus yields reasonable estimates for the temperature of the Earth's surface and atmosphere under a range of conditions. The model can be used to study the response of the climate system to a wide variety of changes such as increasing or decreasing the efficiency of the greenhouse effect. The power of this kind of modeling exercise as a learning tool lies in the fact that it is experiential in nature and enables students to ask "what if" questions and then find the answers to their questions through experimentation.