We talk with author-activist Paul Hawken about his new book, "Drawdown," and why he thinks that global warming may be a blessing instead of a curse. Also, we travel to Acadia National Park in Maine, where National Park Service biologists are experimenting with what's called "assisted migration" to help tree species cope with climate change. Also: sustainable living tips from our advice columnist, Mr. Green, and a moving radio diary from a North Carolina woman demanding clean water for her town.