Glacier National Park's glaciers will be gone in our lifetime

Montana's Glacier National Park is quickly losing an important part of its natural beauty: Its glaciers.

U.S. Geological Survey data released Wednesday shows the park's 37 glaciers, along with two others on federal Forest Service land, have shrunk an average of about 40% since 1966.

In fact, they'll all be gone within our lifetime, warns Daniel Fagre, a research ecologist with the USGS's Northern Rocky Mountain Science Center. In order for the glaciers to survive, the area would need to experience "significant cooling," he said.

But it's likely too late. "Their fate is sealed," forecasted Fagre, who has studied the glaciers since 1991. The trend, he argues, could have an impact on the park and animal life.

"The park-wide loss of ice can have ecological effects on aquatic species by changing stream water volume, water temperature and run-off timing in the higher elevations of the park," Fagre said.

The project with Portland State University geologist Andrew G. Fountain measured the glaciers' deterioration over the past 50 years using aerial photography and satellites. The group was able to trace the perimeter of the glaciers over time, revealing the degradation.

Some masses deteriorated so much, they're no longer large enough to be considered glaciers, which must be at least 25 acres. Some of the glaciers lost up to 85% of their mass.

"While the shrinkage in Montana is more severe than some other places in the U.S.," Fountain said, "it is in line with trends that have been happening on a global scale."

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Fagre blames climate change for the melting. Glaciers, he explained, are steady barometers of long-term Earth changes and don't react to year-to-year weather trends.

"You know there's a long-term trend when the glaciers are all simultaneously melting or growing," he said.

The history of Glacier National Park paints a picture of Fagre's theory. The park's glaciers are estimated at 7,000 years old and "peaked," the USGS said, in the mid-1800s during the "Little Ice Age." In 1850, the park had an estimated 150 glaciers. Since that time, its lost about 85% of its ice area and now has less than 30 glaciers.

Despite the grim outlook, Fagre isn't pessimistic about the ongoing beauty of Glacier National Park, which attracted a record 2.9 million visitors in 2016.

"People certainly come here to see glaciers and like glaciers in the park," he said. "It will still be a beautiful park to visit afterwards."

Follow Sean Rossman on Twitter: @SeanRossman