Stephen Schneider, a leading climatologist at Stanford University, says we can still prevent "a lot of big stuff" by acting now to stop global warming.
How 24 teenage students displaced by Hurricane Katrina learned more about the science of climate change, and then took their knowledge and first-hand experience to lawmakers in Washington DC.
Nadja Halilbegovich, a singer and writer: "Absolutely everyone who lives off our planet and lives on the planet should do something."
