Those who seek adventure often choose the most remote places on Earth: the tallest mountains, hottest deserts, and vast, empty stretches of ice. The last is the subject of Jon Gertner’s book, “Ice Age at the End of the World: An Epic Journey into Greenland’s Buried Past and Our Perilous Future.” He talks with host Krys Boyd about the grueling scientific searches there, even as the ice melts, and the explorers determined to conquer the ice island.