What if we could offset the harms of global warming by spraying particles in the stratosphere or artificially increasing Arctic sea ice? Even if ideas like these were feasible, what might the unintended consequences be? And if there are “winners” and “losers” for a given proposal, who gets to decide what is to be done?
Sammamish High School students were asked to tackle difficult questions like these this autumn as part of my Program on Climate Change (GCeCS) capstone project. What’s more, students had to grapple with these questions while they learned about the basic physics and chemistry of Earth’s climate system. We had decided to teach the fundamentals of climate change through an educational approach known as problem-based learning (PBL). In their 1997 book on the subject, The Challenge of Problem-based Learning, David Boud and Grahame Feletti define PBL as “an approach to structuring the curriculum which involves confronting students with problems from practice which provide a stimulus for learning.” PBL aims to teach how to think critically (“deep learning”), not just how to memorize a laundry list of facts about a particular topic (“surface learning”).
In our case, geoengineering (deliberate changes to the Earth system to alter climate) is the stimulus for learning about climate change. Geoengineering was an ideal choice for our PBL lesson for several reasons. First, students would need to understand important concepts like the differences between the energy coming into and leaving Earth to evaluate geoengineering proposals. Second, students would need to consider issues of equity, feasibility, and governance. The PBL lesson thus had the complexity of tying together the physics of climate change with societal concerns.
Working with teachers at Sammamish High School, Lisa Neshyba and Kristin Larson, and another graduate student, Andre Perkins, we developed a geoengineering curriculum to start off the students’ school year. We introduced students to the project and the basic concept of geoengineering through a short video we created. Students then formed groups that explored one of the geoengineering approaches described in our video, did independent research and wrote a modified version of a scientific paper, complete with peer review by their classmates. The project culminated in a presentation of how their proposals would work scientifically, how feasible each proposal would be to implement, and what the societal implications of implementing the proposal may be.
Early in the semester, Andre and I taught a 2-day lesson on Earth’s energy balance. We used infrared cameras to show how household materials like cardboard and glass interact differently with visible and infrared light. Students learned that most of the atmosphere behaves like a plastic bag in that it allows both types of light to pass through it, but greenhouse gases like water vapor and carbon dioxide behave like glass, allowing visible light through but trapping infrared light. In Earth’s atmosphere, this trapping of infrared light leads to the greenhouse effect. More infrared light is trapped when greenhouse gas concentrations rise, which enhances the greenhouse effect and causes global warming.
Andre and I then led the students through a derivation of a simplified model of Earth’s energy balance which teaches students how visible sunlight and infrared heat from Earth’s surface and atmosphere set Earth’s surface temperature. The geoengineering proposals work by either changing the amount of sunlight reaching Earth’s surface (e.g., by brightening clouds over the ocean) or by allowing more infrared to escape to space by removing carbon dioxide from the atmosphere (e.g., through growing plants for bioenergy). Students now had a mathematical tool to use to explore their geoengineering proposal and the conceptual background necessary to understand whether their proposal would directly reverse anthropogenic climate change (via removing carbon dioxide) or rather mask some of its dangerous effects (via reflecting sunlight).
After students completed their group research projects, they presented short talks to a group of teachers, graduate students and postdoctoral scholars. Although I was conducting field work abroad during these presentations, I was able to participate by reading student papers. The four groups with the best presentations and papers were selected to visit UW and present their work at a special Program on Climate Change seminar on November 15, 2018.
The UW community was very impressed with the depth of the students’ research and the effort put into each of the presentations. In particular, students had clearly put a lot of thought into the risks that might arise if their geoengineering proposals were implemented and what the feasibility and cost of implementation would be compared to significantly cutting carbon dioxide emissions.
Student feedback (both from a survey we sent out after the lesson and direct feedback to the teachers) was quite positive about the lesson being memorable and informative. Importantly, students did appear to effectively learn about Earth’s energy balance: there was a substantially higher fraction of students correctly answering questions about how energy enters and leaves the Earth system in the survey conducted weeks after the lesson was complete as compared to the survey taken before the lesson began. However, students did struggle to incorporate the energy balance equation derived in class into their papers, and future years’ curricula should provide more time and resources for learning the equation.
Much of the success in our PBL lesson came from the close collaboration that Andre and I developed with the Sammamish High School teachers. Our lesson plan changed quite a bit as we iterated ideas over the summer, which ultimately allowed us to develop a lesson that met classroom objectives, effectively took advantage of the expertise UW had to offer, and, perhaps most importantly, held student interest for several consecutive weeks. In addition, Andre and I learned valuable lessons about teaching from experienced educators. The resources we created should provide a strong foundation for this PBL to be taught at Sammamish High School again in future years with enough flexibility for future graduate students to customize the lesson as their and the teachers’ interests and needs evolve. Overall, our experience in creating this geoengineering PBL lesson is a good example of how collaborations between educators and researchers can result in more successful outreach and educational experiences for all involved.
Michael Diamond is a fourth-year PhD student in the Department of Atmospheric Sciences. His research focuses on how the interactions between pollution particles and clouds influence Earth’s climate. Some of his work is relevant to marine cloud brightening, one of the geoengineering proposals included in the PBL lesson.