Allie Balter-Kennedy goes to some of the harshest places on Earth to try to predict how a warming climate will impact the planet’s ice sheets. The Tufts University scientist works with a team, sometimes drilling hundreds of feet down into the ice, to explore changes that have occurred over thousands, even millions of years. The history of Earth that is hidden in the cores helps her foresee its future. To study the cores, she uses a method called cosmogenic-nuclide exposure dating, which...