Environment

Author Timothy Egan argues in The Big Burn that the forest fire of 1910 — the largest in American history — actually saved the forests, even as its flames charred the trees. It helped rally public support, Egan explains, behind Theodore Roosevelt's push to protect national lands.

An estimated one in 10 Americans have been exposed to drinking water that contains dangerous chemicals, parasites, bacteria or viruses, or fails to meet federal health standards. Part of the problem, says journalist Charles Duhigg, is that water-pollution laws are not being enforced.

Colin Beavan, the protagonist of the documentary No Impact Man, spends a year living "eco-effectively" — eating only locally grown foods and, eventually, forgoing electricity and toilet paper. Critic David Edelstein calls the film a "21st-century climate-change comedy of manners."

Director Louie Psihoyos talks about his new documentary film The Cove, an expose of dolphin abuse in Japan. Former Flipper trainer Ric O'Barry joins the conversation.

Journalist Charles Siebert and wildlife biologist Dr. Toni Frohoff explain the uncharacteristically friendly behavior of gray whales off the coast of California.

Alastair Fothergill and Mark Linfield are the directors behind the hit nature documentary series Planet Earth. Their new movie, Earth, uses some of the same footage but is "character-based" rather than "habitat based."

Pulitzer Prize-winning journalist Hedrick Smith details widespread pollution of America's waterways in the PBS Frontline documentary Poisoned Waters.

Intent on documenting the effects of climate change, nature photographer James Balog ventured into ice-bound regions with 26 time-lapse cameras, which he programmed to shoot a frame every daylight hour for three years.

Transportation expert Daniel Sperling estimates that the world's car population — which currently stands at 1 billion vehicles — is likely to double in the next 20 years. Sperling is the co-author (with Deborah Gordon) of Two Billion Cars: Driving Toward Sustainability.

Thomas Friedman is a man bent on revolution. In his new book, Hot, Flat, and Crowded, the three-time Pulitzer Prize-winning journalist writes about the need for a green revolution — and calls upon Americans to lead the charge.