WEST GLACIER, Mont. — The river of ice that hugs Mount Grinnell’s high ridges is neither big nor particularly beautiful, but it may be the most accessible glacier in all of North America. In as little as three hours, an average hiker can traverse the mountain’s well-groomed trail to plant a foot on a frozen relic of the Little Ice Age.
But if you want to see it, you’d better hurry. Grinnell Glacier is disappearing — fast.
This crescent-shaped glacier in Montana’s northern Rockies had been contracting for decades because of warming temperatures. Lately it has been shrinking at a breathtaking clip, losing as much as one-tenth of its mass in a single year. As early as 2030, scientists say, it may no longer exist.
The glacier’s steep decline mirrors that of hundreds of other U.S. glaciers, from California’s Sierra Nevada to the North Cascades to the Central Alaska Range. All are in retreat, yet nowhere are the effects so profoundly felt as here in Glacier National Park, which experts say could be glacier-free by mid-century.
“They’ll be gone in a few decades,” said Dan Fagre, a scientist with the U.S. Geological Survey who monitors the park’s 25 remaining glaciers and plots each year’s losses. “Every year exposes rock that hasn’t seen daylight in centuries.”
The decline of glaciers here and around the world is frequently cited by scientists as evidence of a climate undergoing rapid change. Scientific studies have confirmed that more than 90 percent of the world’s glaciers are retreating, and many of the smaller ones — like the alpine ice sheets of Glacier National Park — are disappearing rapidly.
The impacts extend well beyond the loss of majestic scenery. Thawing glaciers account for about 20 percent of the sea-level rise recorded in the past century, adding to the meltwater coming from polar ice caps and ice sheets. In the United States, the loss of mountain glaciers and snow cover is depriving Western states of a critical water source during the summer, when snowmelt feeds streams and rivers and helps farmers and wildlife survive the dry months.
The problems will almost certainly grow worse for decades, no matter what the world’s nations do to address climate change, scientists say. That’s because at high mountain altitudes where most glaciers are, temperatures are rising faster than in the valleys below, with all signs pointing to still-higher increases in the decades ahead.
Diplomats from more than 190 countries are set to gather in Paris to try to negotiate a historic treaty to curb emissions of greenhouse gases blamed for global warming. The ultimate goal — one that U.S. officials say is unlikely to be achieved during this round of talks — is to cut carbon pollution so that temperatures climb no more than 2 degrees Celsius (3.6 Fahrenheit) over historical averages.
But at Glacier National Park, temperatures already have jumped by nearly 2 degrees Celsius since 1990. What happens to the glaciers in the coming years, climate scientists say, could offer a preview of the broader changes that lie ahead for a warming planet.
“At this trajectory, within a few centuries most glaciers are going to be toast,” said Jeremy Shakun, an assistant professor of earth and environmental sciences at Boston College. “We’re orchestrating something akin to the end of an ice age, but much faster.”
For nearly 25 years, Fagre has been keeping watch on Glacier National Park’s ice fields with the concern of a physician tending to a room full of very sick patients. He scales the mountains regularly to take photographs and measurements, recording a steady decline that is counted in tons and meters.
The most dire scenario predicts that all glaciers in the park’s main Blackfoot-Jackson Glacier Basin could be gone by 2030.
