Fresh off her wolverine study in Montana, wildlife biologist Alex Carter lands a job studying a threatened population of polar bears in the Canadian Arctic. Embedded with a small team of Arctic researchers, she tracks the majestic bears by air, following them over vast, snowy terrain, spending days leaning precariously out of a helicopter with a tranquilizer gun, until she can get down on the ice to examine them up close. But as her study progresses,...

"A riveting, urgent account of the explorers and scientists racing to understand the rapidly melting ice sheet in Greenland, a dramatic harbinger of climate change. Greenland: a remote, mysterious island five times the size of California but with a population of just 56,000. The ice sheet that covers it is 700 miles wide and 1,500 miles long, and is composed of nearly three quadrillion tons of ice. For the last 150 years, explorers and scientists...