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Melting ice: a Schoolroom lesson

September 5, 2018

Volunteers scramble up and down the steep moraines of the Schoolroom Glacier, a small mass of moving ice hidden behind the central peaks of the Teton Range.

From above the colorfully clad figures are dwarfed by the vast terrain. They’ve come from across the West to document the glacier with thousands of photographs for a Grand Teton National Park survey. Each person, 13 in all, carries a camera and captures the ice from many angles, to be compiled into a single 3-D model.

“This is sort of a pilot project,” said Peri Sasnett, the park geologist leading the survey, “to see both if the technique works and if collecting it with volunteers works.”

These surveys usually require the expert skills of climbing rangers, she said, because the standard method involves navigating the icy glacier, avoiding crevasses and the frigid water below. Trained park employees have performed several surveys like this on the Schoolroom and Middle Teton glaciers in recent years.

But now with the new “structure-from-motion” approach, anyone with the stamina to hike the 10 miles to Hurricane Pass can be a scientist for a day, snapping photos from a safe distance.

Volunteers take pictures every few feet from above and below the glacier, and anywhere possible in between, leaving overlap in each photo so they fit together easily. Any image is a valuable data point when combined with many others, making it hard to go wrong. Sasnett calls the technique “very forgiving.”

Once the images are combined a lifelike model will be produced that allows scientists to track how the glacier is accumulating and losing mass from year to year.

The project aligns with one of Grand Teton’s fundamental duties, keeping tabs on its natural resources. Estimates vary, but with global temperatures increasing some studies suggest many glaciers could disappear within the next few decades.

“We count the bears, we count the elk, and we measure the glaciers,” Sasnett said. “As the climate is changing, we’re observing changes in our natural resources, and it’s important to monitor those.”

A world carved by ice

The day before, I joined some of the volunteers on the hike into the park’s interior. Passing through Cascade Canyon we wondered at the glacial origins of our surroundings. The evidence is everywhere: in the canyon’s steep walls and U-shape, the stream running through its bottom, the massive boulders left scattered by glacial conveyor belts.

The ancient ice sheet that scraped its signature on this landscape is long gone, but a few glaciers remain in the park, remnants of the Little Ice Age that ended in the mid-1800s. All told there are 11 mounds of frozen water falling under their own weight in the Tetons.

The most famous are the most visible. To our left, tucked inside the towering cathedral of Teewinot Mountain, Mount Owen and the Grand Teton, is Teton Glacier, the largest in the park. Beyond it is the Middle Teton Glacier, situated along the most popular route up the Grand. Farther north is Falling Ice Glacier, which clings to the east face of Mount Moran.

“The glaciers here are some of the most accessible in the United States in terms of just seeing them from the car,” said Reba McCracken, the park glaciologist who planned the survey but was unable to attend. “There aren’t a lot of other places in the Lower 48 where you can do that.”

But we’re headed deeper, toward where the South Fork of Cascade Canyon nears the park’s boundary with the Jedediah Smith Wilderness. There, just below Hurricane Pass, lies Schoolroom Glacier, a miniature version of its more prominent cousins.

After a full day of hiking, we stop for the night about a mile from our destination. By the time we pitch our tents the last rays of sun retreat up the Grand Teton’s western face, and the temperature drops fast. We’re in glacier territory.

“Too bad there aren’t any hot springs up here,” said Vince Anderson, a city of Denver engineer who was sipping a cup of hot tea, his hood pulled tight over a ski cap.

Sasnett stops by our camp to brief us on the next day’s strategy and sums up why we’re all there in the first place.

“We could do this as park employees,” she said. “We could run around for a few days and just take a jillion photos. But the more people we have, the more photos we have, the better the model.

“And, of course,” she said, “citizen science is a very meaningful way for people to engage with park science.”

Before crawling into his sleeping bag, Anderson reflects on that idea. He’s spent time in the Tetons before, but cherishes the chance to return as a volunteer scientist.

“It’s good to get the public involved,” he said. “You can teach someone about it from a textbook and blah blah blah. But when you come up here you become a stakeholder.”

The archetypal glacier

The next morning the moon lingers over Hurricane Pass as we approach the glacier. We follow a small outflow creek, sparkling with flaky ice, up to its entrance. Nearby a marmot stands guard.

Neat and symmetrical, Schoolroom Glacier earned its name from its classic textbook features.

The glacier has melted backward to reveal its semicircular moraine, a fortress-like enclosure of the rocks it uprooted and deposited there in its heyday. What remains of the ice stands far off from the moraine but still bears the crevasses that mark an active glacier falling slowly and distorting under the pressure.

The ice itself is distinctive. Sassnet describes it as “metamorphic,” a product of many snowfalls compressing under each other over time.

“It’s different from an ice cube in your glass,” she said. “It’s specific to glaciers.”

The water that flows from it is different from tap water, too. The half-frozen tarn at its base is a dull teal, the result of light refracting through a mixture of ice melt and “rock flour,” fine-grained particles the glacier grinds off the stone beneath as it slides downhill.

“It’s just mind-blowing,” said volunteer Ani Graves, a Portland State University geology student, gesturing from the glacier, across the lake and out over the Tetons. “I could stay here for days.”

The glacier would have looked quite different when Fritiof Fryxell visited as the park’s first naturalist in the late 1920s and 1930s. He would’ve found it much closer to the moraine. A few decades before that, when the first government survey expeditions passed through the area, the glacier may have extended all the way to the rocky slopes.

Now Schoolroom Glacier has retreated to a fraction of its original size. This survey is one part of the park’s attempts to understand how that diminishing occurs. But it’s far from simple to determine how a glacier will behave.

“The glacier system is somewhat complicated,” McCracken said. “Especially when you’re talking about glaciers that are up in the high mountains.”

Many, like Schoolroom Glacier, gain mass not only through precipitation but also through avalanches and windblown snow. That can keep them healthier. And McCracken said recent research shows that for some glaciers the rate of melting slows as they shrink and protrude less from the surrounding topography.

With the results of this citizen-science survey the park will have more data to improve its knowledge of glacial activity.

The volunteers prepare to spread out, some to either of the moraine’s wings, some to shoot down from Hurricane Pass. But before they get their shutters going, Sasnett takes a moment to talk safety and asks everyone to stay off the ice.

“Don’t take any risks,” she said. “For either selfies or for science.”

How to gauge a glacier

Glacier surveys are no cakewalk, largely because glaciers generally grow in harsh climates. They call it Hurricane Pass for a reason.

The sky is crisp and blue, but the wind blows fiercely most of the day, neutralizing the sun. Sometimes a strong gust rumbles over the lake and cracks the thin ice around its perimeter.

Unfortunately for Sasnett the wind is also strong enough to interfere with her careful preparations.

She hiked up the day before the volunteers arrived to place “ground control markers” around the glacier. These are large targets, their GPS coordinates predetermined. Without them the model from the volunteers’ photographs would represent the glacier only in the abstract. With coordinates they can create a model of the glacier where it actually sits in physical space.

“If we do it right,” Sasnett said, “we can get down to 2 centimeters accuracy. Your model is only as good as your ground control markers.”

The markers have to be large enough to be seen in photographs, but it appears they are also large enough to catch on the breeze. The wind has blown one slightly out of place.

Sasnett and Kevin Gregson, a park employee helping with the survey, climb to the marker and resituate it. Sasnett attempts to use a high-resolution GPS device called a Trimble (she calls it her “wizard staff”) to relocate the coordinates for the marker, but it won’t connect.

“Maybe we’re too close to a power line,” Gregson said.

Eventually they fix the settings and replace the ground control marker. Gregson sets off across the ice to check the others.

All the photos will still be valuable data, Sasnett said. And climbing rangers will go back to use their standard glacier survey techniques, giving them something against which to check the volunteer survey results.

Data aside, Sasnett said the trip is worthwhile solely as an exercise in citizen science.

Aaron Ximm, who does online archiving for a nonprofit in San Francisco, agreed. He could have hiked to the glacier on his own, but would have missed the insights and interpretation that come with a park-guided trip.

“You get all the benefit of hearing the deeper story,” Ximm said. “It’s a richer experience.”

A fading wonder

Eventually I leave the group and hike up to Hurricane Pass, from which the mountains slope west into Teton Valley. As I crest the pass a retiree approaches and asks the way to Death Canyon.

We walk together a ways, I tell him about the glacier survey, and the conversation turns to the environmental impact of politics and human activity. On the one hand he feels the international community hasn’t done enough to halt climate change. On the other he muses that on a geological scale we cannot do lasting harm to the planet.

“We can’t change this,” he said, pointing to the Tetons. “These mountains will be here long after we’re gone.”

He’s right, of course, in a sense. No matter how much damage the human race inflicts, in the cosmological scheme of things it’s a mere blip. But still, Schoolroom Glacier may be gone long before today’s youngest generations. Does it deserve our attention?

Far below, the colorful specks still scramble around the moraines, their lenses trained on the shrinking mound of ice.

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