What’s my footprint? Using online carbon footprint calculators to demonstrate students’ energy use and environmental impact
A key assumption of environmental education is that people are more likely to act in environmentally sustainable ways if they are aware of the impacts of their lifestyle. In the context of energy use and individuals’ contribution to the accumulation of greenhouse gases, online “carbon footprint” calculators can convert inputs of energy use via electricity, natural gas, driving, air travel, and even diet and purchasing into the amount of carbon emitted or the “Number of Earths” required to support such a lifestyle.
I have developed a computer-based exercise in which students use such carbon calculators to better understand their own energy use. One calculator, (http://coolclimate.berkeley.edu/uscalc), focuses on direct energy use from electricity and natural gas consumption (via per capita energy use in campus residence halls), and miles travelled via auto and airplane. A second calculator (http://www.myfootprint.org) adds such qualitative measures as the relative amount of various food products consumed or shopping conducted. Each calculator compares an individual’s output (in metric tons of carbon dioxide, or Number of Earths) to national or global averages in order to provide context for one’s impact. They also include tools that allow students to model lifestyle changes that would reduce their impacts.
Students (n=31) were surveyed about their knowledge of their environmental impact before and after completing the exercise. Upon completing the exercise, a majority of students (60%) found that their footprints were either somewhat lower or much lower than the average American, though obviously all were much higher than the average global citizen. Many expressed surprise, however, at the extent of the impact of even a “better than average” American. The number of Earths that would be required to support an entire human population at the calculated levels of consumption ranged from 3.5 to 6 Earths. This was a powerful image that drove home to many students how unsustainable their lives would be on a large scale. Furthermore, though at the start of the exercise few students identified sectors beyond electricity/housing or automobile driving that they expected to be significant contributions to their overall footprint, students came to realize that air travel, food, and shopping were also significant components of their carbon footprints. Finally, the calculators gave the students tools to model changes in behavior – including driving or purchasing less, adopting other energy conservation strategies, or changing their diet – that could lessen their own contribution to climate change.