What do "Ice Ice Baby" by Vanilla Ice and "What Have You Done for Me Lately" by Janet Jackson have to do with the Arctic and climate change?   Find out in this season two special, which will take you on a journey into a permafrost tunnel near Fairbanks, Alaska. This tunnel is sort of a Paleo-museum, a network of human-made caves full of mammoth tusks, bison horns, and clumps of 20,000-year-old grass. All of which is frozen—for now.    Learn more about Threshold on our website. Our reporting is made possible by listeners like you. Become a part of our passionate network of supporters on Patreon.   This story/series was produced in partnership with the Pulitzer Center.