Over the past 50 years, the 39 remaining glaciers in Glacier National Park area have shrunk by an average of 39% — and as much as 85% , according to a study released by the U.S. Geological Survey. The map below shows how six of the park's iconic ice masses changed between 1966 and 2015.

Data: Northern Rocky Mountain Science Center; Map: Lazaro Gamio / Axios

Why it matters: The park says there won't be any active glaciers in 15 years if the current trend continues. Melting of the 7000-year-old glaciers could affect run-off into rivers and streams and, in turn, wildlife, as well as tourism.