Human Impacts on Biogeochemical Cycles

Mari Titcombe Lee, Environmental Program, Colorado College


Human Impacts on Biogeochemical Cycles is an introductory environmental science course examining the pressures of modern civilization on natural Earth cycles. The course uses inquiry based learning to cover basic principles of chemistry, as well as some biology and geology. Students learn about environmental feedbacks through computational modeling (STELLA software) of population, nitrogen and carbon cycling, and simplified global climate models.

Course URL:
Course Size:

Course Format:
Lecture and lab

Institution Type:
Private four-year institution, primarily undergraduate

Course Context:

The course introduces principles of chemistry, geology and biology and serves as an equivalent to one semester of general chemistry. It is a 200 level environmental science course. It is the final science course required of environmental policy majors, and sets the foundation for upper level science courses for environmental science majors.

Course Content:

This course covers general chemistry topics in an inquiry based learning environment. Modeling activities tie these concepts to specific natural environmental cycles and give students a chance to explore how various human activities affect these cycles.

Course Goals:

Students will be proficient in concepts of general chemistry and use these concepts to explain environmental phenomenon, both qualitative and quantitative. Students will gain experience in reading and interpreting published scientific papers and will use literature to build systems models. Students will understand what is meant by systems thinking and be able to integrate knowledge into models of complex environmental cycles. Students will better understand their individual ecological footprint and the combined footprint of our modern way of life.

Course Features:

Students team up in groups of two or three to complete final modeling projects in which they chose an environmental, economic or policy issue to build into a complex systems model of a human influenced natural cycle with feedback. Past projects have included an ocean acidification model tied to simple CO2 emission and atmospheric distribution models, bark-beetle infestation model including drought, freezing and planned and natural fire pressures, and a model examining the role of public policy on the adoption and implementation of sustainable energy technologies.

Course Philosophy:

This course was designed by an array of faculty members in mathematics and natural science departments and provides a truly interdisciplinary introduction to environmental science. The course is taught by members of the Environmental Program with backgrounds in chemistry, biology, mathematics and geology. The course content is chosen to directly apply basic science concepts to understanding local, national and global environmental challenges. It is a challenging course for our policy majors and is intended to give them working knowledge of the strengths and limitations of computational modeling, as well as an increased ability to read and digest peer-reviewed scientific literature. Colorado College operates on a unique block schedule, with students focused on one course at a time, and each course lasting roughly four weeks. This format demands teaching outside of standard lecture styles. This often requires favoring depth over breadth, and this course dives deeply into a few major natural cycles. The inquiry based learning style helps students develop as sense of discovery and self direction, enabling them to further integrate other topics of environmental concern not covered explicitly in this course.


Students complete final projects in which they create their own computational models. Students work in small groups (1-3 students) and have access to instructors to help move past sticking points in model development. Students present their final models and learned outcomes of their studies in class, and turn in final reports to be graded. Students also take American Chemical Society standardized chemistry examinations to ensure that students are gaining a sufficient qualitative and quantitative background in general chemistry.


Human Impacts Course (Acrobat (PDF) 155kB Jun21 12)

References and Notes:

Chemistry in Context: Applying Chemistry to Society, C. Middlecamp (Editor in Chief)
We also read from Richmond, Introduction to Systems Thinking; Kauffman-Cleveland, Environmental Science, Sterman: Business Dynamics, and selected literature papers