Tulsa, Oklahoma – As we suffer through the current deep-winter cold spell, our thoughts might turn to polar bears, which thrive in such icy, blustery conditions. For this edition of our show, we speak with the author, marine artist, and naturalist Richard Ellis, whose new book is "On Thin Ice: The Changing World of the Polar Bear." As Ellis explains on our show today, the fate of the polar bear is closely associated with global warming. Indeed, as global warming immediately and undeniably threatens our planet's ice caps, it also threatens the very existence of the polar bear --- for this animal cannot survive without such ice caps. And it cannot live or hunt anyplace else. As one critic, writing in The New York Times, has noted of this book: "[Ellis offers a] timely, passionate, and comprehensive survey of polar bear history, lore, biology, and politics. Ellis is a prolific and graceful writer who's written some of the best natural history books of the past decade.... If you're looking for a complete digest of the history of human-polar bear relations, there's nobody better."