Project records melting glaciers
Data show Cascades ice dwindling fast
HOLDEN VILLAGE, Wash. – Lyman Glacier, sitting just below 8,459-foot Chiwawa Peak, is dying.
Nearby, Spider Glacier has already passed away. The scientist who pronounced it dead three years ago believes that one-third of the glaciers in the North Cascades – including Lyman – are doomed.
Mauri Pelto says the other two-thirds may have a chance, if the world does something to stop continued global warming. Pelto is an environmental science professor at Nichols College in Dudley, Mass., and has studied glaciers and climate change for more than two decades.
In August, he completed his 25th hiking trip to several North Cascade glaciers. He’s been watching and measuring the great slabs of moving ice every year since 1984.
It is the largest study of glaciers in the North Cascades, home to one-third of all glaciers in the lower 48 states.
He visits 10 glaciers every year for in-depth measurements and monitors 37 others with less regular trips. Five of them have already died, and all of the glaciers he’s studying are now retreating. They’ve lost 20 to 40 percent of their volume.
The former skeptic
Pelto says when he first learned about climate change as a graduate student at the University of Maine, before he started this study, he was skeptical.
“I’d been to a couple conferences related to global warming, and as a skier, I hated the idea. I was looking to find a hole in the argument,” he says.
Instead, he found the science convincing.
Ronald Reagan was president, and the National Academy of Sciences was calling for someone to monitor glaciers across an entire mountain range. Pelto says science budgets across the nation were being cut, and he knew no one would likely take on the academy’s recommendation. So he decided to take the challenge himself by making it his graduate thesis. He started the North Cascade Glacier Climate Project, which he intends to be a 50-year study of nearly 50 glaciers in the North Cascades.
He chose glaciers to represent different geographical features – some are high elevation, some are lower, some are north-facing, some face south, some are in Western Washington, and some – like Lyman – are on the east side of the range.
Now 46, Pelto finds it hard to believe that anyone still questions that global warming is real.
Pelto says he also wonders how people – especially those who depend on water from the glacier-fed rivers, lakes and streams on the east and west slopes of the Cascades – will react once they realize what it means to lose these frozen reservoirs of water.
Hiking the glaciers
At the headwaters of the Chiwawa River Valley, a few miles into the Henry M. Jackson Wilderness, the trail opens out to alpine Spider Meadow. It’s a popular spot for both foot and horse campers. Pelto and his team arrive at dusk on Aug. 10, set up the tent, have a quick dinner, get to bed and then wake early the next day for the steep climb to Lyman Glacier.
As the sun creeps over the peaks, they climb 2,300 vertical feet in a few long miles to Spider Gap before dropping down 1,000 feet to the glacier. It’s one of nine they’ll visit on this two-week trip. Altogether, they’ll hike more than 100 miles and climb about 35,000 feet.
Lyman Glacier and its lakes are at the headwaters of Railroad Creek, which flows past Holden Village into Lake Chelan and then the Columbia River.
Pelto’s team this year includes his 18-year-old son, Ben; Brad Markle, 22, a recent Pomona College graduate from Corvallis, Ore.; and Tom Hammond, a network engineer at the University of Washington who is Pelto’s field scientist.
Finding a ‘mass balance’
“See that rust-colored boulder on the right?” Pelto asks, pointing to the only large boulder on the east side of the lake. “My first year here, the glacier went all the way to there,” he says. His first year here was in 1986, and the rock is now several hundred feet from the glacier.
But their talk doesn’t focus on the receding ice. They immediately get to work, screwing together a heavy steel probe that they systematically punch through the snow until it hits ice. It measures how much snowpack remains from last winter.
They repeat this every 100 meters, or 330 feet, back and forth across the glacier.
“We’re trying to get a mass balance, how much snow it gains versus how much it loses,” Pelto says. “It’s like balancing your checkbook,” he says. If you continually take out more money than you put in, eventually you run out.
Glaciers form when more snow falls in the winter than melts in the summer. They die when more snow melts, and melting works its way farther and farther into the ice slab until there’s nothing left.
When they die, these spots still gather snow each year, like the former Spider Glacier above Spider Meadow. The snowmelt from it still flows into the Chiwawa River and later joins the Wenatchee River. But now that the Spider Glacier has melted, there will be no ice to continue feeding the Chiwawa River once last year’s snow melts.
Unless there’s an unseasonably cool fall or early winter this year, Pelto predicts, Lyman Glacier will shrink again this year. Only 11 feet of snowpack were left at the deepest spot on the glacier by mid-August. In past years, he says, 10 to 12 feet of snow has melted from this glacier between mid-August and first snowfall.
Pelto and his team use a laser to measure the glacier’s size and distances to various points. They use an inclinometer to calculate the incline, or slope, at every spot they measure and take its GPS location. As they work their way back and forth across the glacier, they come to a dozen or more crevasses that jut deep into the glacier to the mountain below.
They’re working close to the glacier’s terminus now, the cliff-like edge of the glacier where it suddenly drops off to meet the lake below. Taking measurements around the crevasses, they’re careful not to step on the bright white snow at their sides, which could give way and send them into the abyss.
Layers of history
This year, it’s too dangerous to venture to the edge of the glacier, which drops 80 feet to the lakes below. Instead, they hike around to its base and count at least 38 layers of ice, each a different year in which more snow fell than melted, eventually turning from snow to ice under the weight of the following year’s snowpack.
The ice layers represent snowfall dating back about a century, Pelto estimates. A glacier has been here for the last 5,000 years, at least, he says. But the ice at the bottom of this glacier, which scrapes and mixes with the mountain below it as it moves, is only about a century old. “North Cascade glaciers are small and have high accumulation rates and melt rates. The result is faster motion and no pockets of old cold ice frozen to the bed,” he explains.
Unlike the rings in a tree, there is not a layer for every year, he says, because there are many years when there’s no extra snow to form that ice layer – especially in recent years.
Pelto has visited this glacier 12 times since he first came to take measurements in 1986; this is not one of the 10 glaciers under intensive study, but he tries to come here often.
His data go back further than his first trip here.
Pelto found William Long, a Cashmere geologist who often came here – indeed, spent his honeymoon here in 1944 – and had old photos of how it looked in the ’40s and ’50s.
Pelto also used records from the Washington Water Power Co., which monitored the Lyman Glacier from 1920 to 1949. From this information, his own data, and a study that shows where the glacier retreated after the Little Ice Age of the late 1800s, Pelto has calculated this glacier’s rate of retreat. Pelto figures it’s about one-third its former size.
And, it’s providing about one-third of the water it once did. Since the Little Ice Age in about 1890, the glacier has receded about 1,365 meters – a couple hundred meters short of a mile. For the last 50 years, it’s retreated about 33 feet per year.
He predicts it will disappear completely in 30 to 50 years.