UNIVERSITY STUDENTS’ IDEAS ABOUT CLIMATE CONCEPTS LACK SYSTEMS DYNAMICS THINKING

Based on think-aloud interviews (n=53), we evaluate the ideas undergraduate students hold about fundamental climate science concepts involving stocks and flows of energy and carbon. The research objective is to define common mental models to help develop more effective learning activities and assessments.

During these interviews, participants draw, write, and verbalize their thoughts in response to written prompts. One prompt explicitly asks about stocks and flows of water in and out of a bathtub. Students also explain how the greenhouse effect works, and explain the patterns they observe in the Keeling curve – a record of atmospheric CO₂concentration since the 1950s measured at Mauna Loa, Hawaii. Expert explanations of each of these topics require systems dynamics thinking and the understanding that imbalances between inflows and outflows result in changes in stock (energy, carbon, or water) over time.

One-third of interviewees correctly combine inflow and outflow information to deduce changes to the stock of water in a bathtub. The majority of these, however, do not also apply those ideas to climate contexts. For the climate questions, students typically emphasize either a key inflow to the system, or a key outflow, but rarely both. For the greenhouse effect, most express models that emphasize inflow in which energy comes in, gets stuck, and stays. For the seasonal cycles in the Keeling curve, only 8 of the 31 who mention photosynthesis also discuss respiration. To explain the long-term trend in the Keeling curve, students focus on inflow processes (e.g. fossil fuel burning), correlating the most logical flow to the clearly increasing stock. The omission of relevant flows in the opposite direction reveals a lack of consistency between student explanations of how particular systems function, and the systems’ behavior over time.

While it may be unrealistic to expect students to articulate systems thinking in open-ended questions, those who do apply both inflow and outflow ideas to the climate scenarios are about twice as likely to also succeed at the bathtub problem. We propose that learning opportunities that explicitly use a systems dynamics framework may better equip students to transfer systems ideas to climate scenarios and to consider the full range of options to mitigate future climate change.