Studying Carbon Cycles
Leanna Jackan, Science Teacher

In the week before spring break, AP Environmental Science has been covering climate change. In the morning, students have been exploring the scientific concepts of climate change by working through a staff-guided series of High Adventure Science climate modules. These modules cover the greenhouse effect, positive feedback loops, sources and sinks of carbon, and so on. 

Another facet of learning about climate change is learning about what has caused fluctuation in historic climate patterns in Earth’s geologic past and what evidence we have for those fluctuations. Our climate is an extraordinarily complex system and a part of that system is the carbon cycle. Often the carbon cycle is broken into two cycles, the slow carbon cycle, and the fast carbon cycle. Carbon in the slow carbon cycle is sequestered for millions and millions of years. Carbon in the fast carbon cycle is sequestered for decades or hundreds of years.

After hearing about trends in paleoclimate and the slow and fast carbon cycle, students collected data in an effort to try and quantify how much carbon dioxide has been sequestered in Lowenwood trees via photosynthesis. They used a protocol modified from the Science Education Resource Center at Carleton College’s “Carbon in Local Trees” Lesson (Adapted from Janowiak, M.: "The Carbon in Trees" activity from Future Fuels from Forests Teacher Institute. 2009, Northern Institute of Applied Science, Michigan Technological University.)  

Students used a Biltmore Stick to estimate the diameter at chest height of the trees, recorded the species of tree, and classified the trees as hardwood or softwood trees. This data was entered into an excel file that calculated the metric tons of carbon dioxide sequestered by the tree. Students then looked up a variety of carbon emitters to compare with.

According to the students’ estimates, in roughly 255 trees on campus, there is about 750 metric tons of carbon dioxide sequestered.