The Developed-Developing Nations assessment model couples the environmental system (carbon cycle), land use, population growth and energy system to estimate the impact of any of these on the evolution of carbon in the atmosphere. The model was developed initially within the software STELLA because it allows for ease of learning, and the ability to conduct quick assessments, although this somewhat is at the expense of sophistication of the underlying science. The model is explained in the publication: Crawford-Brown and LaRocca, “Teaching Systems Principles and Policy Applications using a Reduced-Scale Global Warming Model”, Journal of Geoscience Education, 54, 101-120, 2006. It is based on a simplified model created for use at the original Rio Conference, when it was found that the existing scientific models required too much computational time to allow simulations of policies during the course of discussions. The paper is attached, shown as the file called ESSE Reduced Scale Model, where ESSE refers to Earth Systems Science Education (the NASA-sponsored programme under which it originally was developed), and Reduced Scale refers to the fact that it reduces the complexity of the model to allow for rapid simulation.
The full model is shown diagrammatically in the figure below:
Notice that the model consists of several sub-models:
The model contains components for Developed Nations and Developing or Underdeveloped Nations in regard to the Population sub-model and the Energy Systems sub-model. The Land Use sub-model and the Carbon Cycle sub-model are global rather than region-specific. In the uses of the model in this project, the Radiation Balance function is disabled because we are focussed on global atmospheric carbon as the policy target. Throughout, the units of estimates are billions of metric tons (BMT) of carbon in the atmosphere, and all other units are scaled accordingly. We follow only carbon (not all greenhouse gases), in whatever form the carbon appears in the carbon cycle.
The model equations, including their execution in the STELLA software, can be seen on The Model Equations page.