Earlier this summer, a group of scientists spent two weeks in Indonesia atop a glacier called Puncak Jaya, one of the few remaining tropical glaciers in the world. They were taking samples of ice cores to study the impacts of climate change on the glacier. Lonnie Thompson, a professor of earth sciences at Ohio State University, led the team and what he witnessed shocked him: The glacier was literally melting under their feet. Thompson tells NPR's Guy Raz he has conducted 57 expeditions around the world, but this trip was unusual. It was the first one where he experienced rain...