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A hiker descends Saint Mary

The case of the disappearing glaciers

Colorado's majestic ice masses are melting fast. Visit these five before they're gone.

October 7, 2021

By Mark Cox

One of the defining challenges of climate change is that its progress can be so gradual, you don’t really notice it happening. But there are exceptions.

The 14 majestic glaciers of northern Colorado are melting away at a precipitous rate. And that means they are providing a rare, real-time insight into the impact of global warming.

“These glaciers are the canary in the coal mine,” said Tom Bellinger, affiliate professor of Environmental Science in the Department of Earth and Atmospheric Sciences at Metropolitan State University of Denver. Because of their outlier status and limited size, he explained, we can measurably see them disappear year after year.

Among the hardest hit is St. Mary’s Glacier, situated at a popular hiking spot that Bellinger last visited four years ago. But things change quickly. “When I recently saw current (video) of the site,” he said, “I was amazed – and horrified – by how much it had shrunk in such little time.”

The diminished glaciers, along with an emergency water shortage on the Colorado River, indicate how global warming is hitting the Centennial State. “As things dry out in Colorado,” Bellinger said, “we’re seeing more extreme droughts and dust storms, which then impact further on the glaciers and compound the problem.” 

Hikers ascend Saint Mary
Hikers ascend Saint Mary's Glacier Trail in the Arapaho National Forest. Photo by Shutterstock.

Ticking clock

If the outlook really is so bleak, then how long do these historic landmarks – part of Colorado’s natural ecology – have left? “Sadly, some of the smaller glaciers will probably be gone completely in 10 to 20 years,” Bellinger said, “while the larger ones might last for another 60 years.”

That’s bad news for Front Range water supplies. Glaciers are an important water source for Boulder and Denver – metropolitan hubs with growing populations. Their retreat will mean lower river flows, which will negatively impact agriculture, aquatic life, fisheries and soil moisture, while leading to increased competition for water rights.

While we’ll always get some water from snowpack in the Rocky Mountains, Bellinger explained, that melts earlier in the year and can’t be counted on in the latter, colder months.

“The key benefit of the glaciers is that they pass water along to the rivers all year long,” Bellinger said. Without them, Coloradans would face a severely reduced water supply throughout the second half of the year. Cities would have to navigate severe restrictions and extra costs, and agriculture would be massively impacted.

“Believe me,” Bellinger said, “that is not a situation we want to be in.” He argues that we urgently need to stabilize or reverse the current damaging process because once the water cycle is disrupted, we will all suffer. “These disappearing glaciers are a bright, flashing warning sign,” he said, “and it’s high time we all took notice.”

RELATED: Colorado rocks! Here are the state's best geological hikes

Visit or hike these five Colorado glaciers (before they’re gone)

Professor Tom Bellinger shares his insights on the greatest glaciers in the state.

St. Mary’s Glacier (Idaho Springs)

It’s no wonder that this site is so popular. Although technically a semipermanent snowfield rather than an actual glacier (it’s a static body of snow as opposed to a moving river of ice), St. Mary’s is accessible, beautifully scenic and an easy drive for Denverites.

Andrews Glacier (Rocky Mountain National Park)

This pretty glacier sits in a cirque (a bowl-shaped depression in the side of a mountain) just below the rocky summit of Otis Peak and flows into a small lake. It’s undeniably beautiful, but given that it sits just below 12,000 feet above sea level and is hidden from view for most of the walk up, this is one view you’ll have to earn.

Arapaho Glacier (Nederland)

The largest (and maybe craggiest) glacier in Colorado once provided Boulder with much of its water, but it has lost 52% of its mass in the past century and continues to decline. While the site itself is closed to the public, a nearby trail will give you a majestic view of the glacier with the city as a backdrop.

Sprague Glacier (Rocky Mountain National Park)

The northernmost entry in our list is an incredibly picturesque cirque glacier, which feeds into several small alpine lakes. Situated on the east side of the Continental Divide, it’s a justifiably popular spot in an unbeatable location.

Isabelle Glacier (Indian Peaks Wilderness)

Half the joy of this route is in viewing the stunning scenery – lakes, wildflowers, rolling hills – on the way up. And once you’re up there at 11,920 feet, the glacier and the surrounding jagged peaks make for a jaw-dropping spectacle.


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