MOUNT BAKER, Wash. -- Mauri Pelto digs his crampons into the steep icy slope on Mount Baker in Washington state and watches as streams of water cascade off the thick mass of bare, bluish ice. Every 20 yards, the water carves vertical channels in the face of the glacier as it rushes downstream.
The little snow from last winter is already gone, so ice is melting off the glacier at a rate of nearly three inches a day this summer, he said.
"At the rate it's losing mass, it won't make it 50 years," said Pelto, a glaciologist who returned this month for the 32nd year to study glaciers in the North Cascades range. "This is a dying glacier," he said.
Glaciers on Mount Baker and other mountains in the North Cascades are thinning and retreating. Seven have disappeared over the past three decades, and glaciers in the range have lost about one-fifth of their overall volume.
The shrinking glaciers here mirror what is happening around the U.S. and worldwide: As the planet warms, glaciers are losing volume, some faster than others.
Two of the largest glaciers in Yosemite National Park in California have retreated over the past century, losing about two-thirds of their surface areas. In Alaska, a recent study of 116 glaciers estimated they have lost about 75 billion metric tons of ice every year from 1994 to 2013. In Montana, scientists are already seeing the impacts in increased stream temperature and changes to high-elevation ecosystems. In 1850, there were 150 glaciers at Glacier National Park; now there are 25.
"These glaciers are, from a geological standpoint, rapidly disappearing from the landscape," said Dan Fagre, a research ecologist with U.S. Geological Survey stationed in Glacier National Park. "They're so small and vulnerable that they could be gone in a matter of decades."
Glaciers --thick masses of accumulated snow that compress into ice and move -- are important indicators of climate change because they are driven by precipitation and temperature.
The glaciers on Mount Baker, a volcanic peak about 125 miles northeast of Seattle, provide a critical water source for agriculture, cities and tribes during the late summer. The icy glacial melt keeps streams cool for fish and replenishes rivers during a time of year when they typically run low.
This year, a record low snowpack in Washington state and warmer temperatures have made it one of the worst Pelto has seen in over three decades.
"They're losing volume at a faster rate than ever before," Pelto said. "If you can't sustain a glacier at a place like this in the Lower 48 states, there's no hope."