By the year 2100, many scientists believe that the Earth's average temperature could rise by as much as six degrees Celsius. In a compelling investigation, National Geographic leads a degree-by-degree journey to explore what each rising - and critical - degree could mean for the future of our people and planet. Through powerful filmmaking and intimate profiles, this special illustrates how global warming has already affected the reefs of Australia, the ice fields of Greenland, and the Amazonian rain forest. With a sobering look at the effects of our world's insatiable appetite for energy, Six Degrees Could Change the World explains what's real, what's still controversial, and how existing technologies and remedies could help dial back the global thermometer.