In this activity, students will examine graphs of greenhouse gas (GHG) emissions and their increases associated with human activity. They will focus on carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCs), and ozone. They will calculate some personal contributions to emissions. When students finish this activity, they will be able to identify sources of the major greenhouse gases and identify the current trends in atmospheric concentrations. Students also will be able to calculate greenhouse gas emissions on personal and larger scales. The teacher's guide contains detailed background material, learning goals, alignment to national standards, grade level/time, details on materials and preparation, procedure, assessment ideas, and modifications for alternative learners.