In the 19th century, the corner of northern Montana now known as Glacier National Park was dotted by at least 150 giant blocks of ice. Now, thanks to global warming, there are only about 25 glaciers left in the park, and all of them might be gone before 2080.

A new study by the United States Geological Survey and Portland State University has focused on just how much glaciers have shrunk since 1966, using aerial photography and satellite data to construct maps of the melting ice. Of the 39 glaciers the researchers tracked through time — all but two of which are part of the national park, with the others on nearby U.S. Forest Service land — only 26 of them are still big enough to still count as glaciers in 2017.

This image above shows the shrinking perimeter of the park’s Sperry Glacier, with the lines representing its size in the late summer of 1966, 1998, 2005, and 2015. According to Portland State geologist Andrew G. Fountain, what he and his colleagues at USGS observed in the park was more severe than what’s going on elsewhere — it makes sense a place called Glacier National Park would feel the loss of glaciers most strongly — but it’s in line with what climate change is causing elsewhere in the United States and the rest of the world.

The loss of the glaciers figures to affect tourism to the area — the park attracted nearly three million people to this remote part of Montana in 2016 alone — but it could also have a much deeper impact on the park’s ecosystem and wildlife. After all, the ice doesn’t simply disappear as the glacier shrinks, and the melted water can change the size and temperature of nearby rivers, which can create problems for marine species adapted to how the park used to be.

Climate models suggest at least some of the remaining glaciers in the park could disappear entirely sometime between 2030 and 2080. Probably best to consider a visit sooner rather than later, then.