This is one of the many interactive labs provided by Annenberg Learner, and it is part of a course for high school teachers called, The Habitable Planet. While the full course is designed for teachers, the labs are appropriate for use with high school students. This interactive simulation “uses a robust model of the carbon cycle to give you an intuitive sense for how carbon circulates through the atmosphere, biosphere, oceans, and crust.” Thus, the simulation can help students understand the carbon cycle on the global scale. In particular, this simulation allows users to experiment with how human inputs affect the carbon cycle and the level of atmospheric carbon dioxide. Users can manipulate projected fossil fuel use, deforestation, emissions levels, and feedback caused by melting tundra. The simulation then demonstrates the effects of these changes on projected atmospheric carbon dioxide levels and carbon storage levels in other environmental sinks. The simulation is supported by three lessons that guide users toward understanding the key concepts presented in the simulation. The simulation is also accompanied by a downloadable data table (Word document) to record observations made during the simulation.