“If you watch a glacier or ice sheet for a month, or a year, you’re not going to learn much about what the climate is doing to it,” said lead author Benjamin Smith, a glaciologist at the UW Applied Physics Laboratory. “We now have a 16-year span between ICESat and ICESat-2 and can be much more confident that the changes we’re seeing in the ice have to do with the long-term changes in the climate.