Teaching Systems Principles and Policy Applications Using a Reduced-Scale Carbon Cycle Model for Global Warming

Journal of Geoscience Education, May 2006 by Crawford-Brown, Douglas, LaRocca, Sarah

ABSTRACT

The Carbon Cycle module provides a tool for interdisciplinary, team-based assessment of the causes and solutions to changes in carbon dioxide in the atmosphere, for use in high-school or introductory undergraduate courses in earth systems science or environmental science. A reduced-scale model (i.e. a model whose complexity is well below that of full scientific models, and yet reproduces the behavior of those more complex models) has been developed that allows students to systematically explore the relationship between a variety of biogeochemical processes, and their interactions with social processes, as these relate to the accumulation of carbon in the atmosphere. The module walks the students through the construction of the model, through exercises in which simulations are performed of changes in either environmental processes or society's use of energy, and through use of the model to identify effective policies for reduction of atmospheric carbon dioxide. Through use of such a module, students can understand the interactions between the disciplines that underlie earth systems and environmental science, develop needed mathematical skills too often lacking in introductory earth systems courses, and explore tne role of scientific analysis in identifying and selecting environmental policies needed to reduce the accumulation of atmospheric carbon dioxide.

INTRODUCTION

An important aspect of global warming is the degree to which human society plays a role in modifying the behavior of interconnected systems responsible for the carbon cycle. Humans are both a partial source of the recent increase in greenhouse gases (IPCC, 1996) and the primary focus of attention in developing environmental policies. The study of global warming, therefore, is an ideal topic for learning the principles of earth systems science, which increasingly recognizes the important role of humans in natural processes that involve material flow through the system. The carbon cycle and climate change also provide excellent topics around which to build inquiry-based activities for students, as it places scientific analysis into the context of societal decisions and environmental policy.

While there are many interesting aspects of the carbon cycle that can be explored experimentally, it clearly is impossible to test alternative policy scenarios. As a result, models such as those used by the Intergovernmental Panel on Climate Change (IPCC, 2001) have been developed to simulate the emissions of carbon, the cycling of carbon between the compartments of the earth system (atmosphere, lithosphere, oiosphere and hydrosphere), the resulting concentration of carbon (in the form of carbon dioxide) in the atmosphere, and the effect on temperature and climate.

These models, however, have a complexity- both scientific and computational- that generally prevents their use in the classroom or as the focus of inquiry-based activities. They simply are not accessible to students in introductory environmental science, geoscience or earth system science classes. If routine use in a classroom is to be expected, teachers require a modeling system that is relatively simple to learn and apply; that is built within a readily available platform; that contains the relevant scientific, social and policy features of the more complex models, albeit in a simplified form; and that still succeeds at producing simulations of future environments that mimic those predicted by the more complex models (the term "reduced form" is used in the policy world to describe such simplified models that retain the general behavior of the more complex models).

This paper reports on the use or such a modeling system for guiding activities focused on the carbon cycle, developed for advanced high school (AP Environmental Science) and undergraduate study in the United States. It was produced, applied and assessed initially in collaboration with the NSF and with the Earth System Science Education (Johnson et al, 1995; KaIb et al, 1997) project, which has the aim of integrating the earth sciences and relevant social sciences to understand complex environmental processes. The model allows students and teachers to simulate changes in earth system parameters, including changes in societal energy use or land use or population growth, and to study the effects of those changes on the global carbon cycle and atmospheric carbon. The model is implemented within STELLA (see the website at www.hps-inc.com), and has been tested against predictions from the IPCC modeling effort (as described later). It also has been applied successfully in a range of classroom settings, forming the basis for the modeling lab component of a freshman Introduction to Environmental Sciences course at UNC-Chapel Hill; for inquiry-based, and team-based, student activities in the senior year; and for day-long activities conducted by high school students who attend an annual science symposium at UNC-Chapel Hill designed to attract the most talented students into the science programs on this campus.