New Data Show Drastic Shrinking In Montana's Glaciers

May 10, 2017

Newly released data say glaciers in Montana’s Glacier National Park have shrunk as much as 85 percent since the 1960s, according to the U.S. Geological Survey. Some are now so small they’ve lost the characteristics that make them glaciers.

All of the park’s 37 named glaciers are smaller than they were 50 years ago — on average, 39 percent smaller. This doesn’t surprise Dan Fagre, a research ecologist with the USGS.

"It's continuing the trend of retreating," he says.

Scientists use a wide variety of instruments to measure glacial movement and retreat. These instruments can be large and bulky, and all of them must be carried by hand to the glaciers.
Credit USGS

Fagre says the shrinkage in Montana mirrors what’s happening to glaciers and ice sheets around the world as the climate warms. But that warming is happening faster in western Montana, where temperatures have increased at a rate almost double the global average.

"We aren't any different, it's just that it's a little more extreme here because of the small sizes of our glaciers," he says.

Scientists from the USGS and Portland State University used digital maps from aerial photography and satellites to measure the perimeter of glaciers and compare them over time.

They found that some of the park’s namesake ice rivers have decreased drastically in the last half-century. For example, Boulder Glacier is 85 percent smaller than it was in 1966. It’s so small now that it’s no longer considered an active glacier; there are 10 more like it. But others are hanging on.

"Well, a classic example is one called Weasel Collar," he says.

Weasel Collar Glacier has lost just 10 percent of its ice since 1966.

"And it's, you know, tucked in this little rocky trough, and so it's extremely well protected and i wouldn't' be surprised if it's one of the last glaciers to disappear in GNP," he says.

Fagre says Glacier National Park will likely lose its last glacier within his lifetime.