Topic(s): Carbon Cycle, Greenhouse Gases, Anthropogenic Changes
Grade Level: Middle (6-8), High School (9-12), College Lower (13-14), College Upper (15-16), Informal Education
This video segment from 'Earth: The Operators' Manual' explores how we know that today's increased levels of CO2 are caused by humans burning fossil fuels and not by some natural process, such as volcanic out-gassing. Climate scientist Richard Alley provides a detailed step-by-step explanation that examines the physics and chemistry of different "flavors," or isotopes, of carbon in Earth's atmosphere.