As It Happens

This Alaskan glacier is moving at an 'awe-inspiring' pace, 100 times faster than usual

A massive glacier in Alaska is on the move for the first time in 64 years, and U.S. National Park Service geologist Chad Hults got to experience it first-hand.

The Muldrow Glacier on Mt. Denali is undergoing a rare, but natural, phenomenon known as a 'surge'

The Muldrow Glacier on Mt. Denali, pictured here on March 17, is experiencing what geologists call a 'surge' - a rare, naturally occurring movement of ice that has increased the speed of the glacier's movement by about 100 times its usual rate. (National Parks Service)

Story Transcript

A massive glacier in Alaska is on the move for the first time in 64 years, and geologist Chad Hults got to experience it first-hand. 

The Muldrow Glacier on the north side of Mt. Denali is moving 100 times faster than its usual speed — a rare, but natural, phenomenon known as a surge. 

Hults, a geologist with the U.S. National Park Service, stood atop the surging glacier late last month. He reached the peak by helicopter and installed time-lapse cameras and GPS markers to measure the speed of the surge.

"It was just a spectacular sight. It was all crevassed up. There's massive ice walls that are crashing ice down the sides, down the lower portion. And there's these major shear zones on each side of the glacier," Hults told As It Happens host Carol Off. 

"It's just amazing. It's just so exciting to be a geologist studying this surge."

National Parks Service scientist Chad Hults installs a time-lapse camera near the Anderson Pass on Mt. Denali in Alaska on March 28 to capture footage of the surging glacier, visible behind him. (National Parks Service)

A surge is a cyclical event in which a glacier's ice begins to flow downhill at faster than usual speeds. Muldrow is currently moving between 10 to 20 metres per day. On a normal day, it moves between 10 and 30 centimetres, Hults said. 

The surge was first spotted on March 4 by Chris Palm, a pilot with sightseeing company K2 Aviation, who was flying near the north side of Denali when he noticed the usually smooth glacier was covered in cracks, known as crevasses.

He snapped some pictures and flagged them to researchers at the National Park Service. Satellite footage confirmed the glacier is, indeed, surging. 

Cracks in the ice called crevasses have formed on the Muldrow Glacier as a result of the surge. (National Parks Service)

It's exciting news for scientists like Hults. Glacial surges are a little understood and extremely rare phenomenon. They only occur on about one per cent of glaciers worldwide, and they're usually decades apart.

"What causes the surge? It's still not totally understood because a lot of the process of what causes a glacier to surge is internal to the glacier, and it's hard to study," Hults said.

"But through studying glaciers through the last few decades, glaciologists have found that it's a combination of the geometry of the glacier [and] ice build-up at the upper reaches of a glacier. Because of that geometry, that ice build-up can't just be released slowly through normal glacier flow."

Muldrow is on a cycle of surging approximately every 50 years. It last happened in 1957. "So it's a little bit overdue," Hults said.

While the surge itself is perfectly natural, some scientists suspect climate change — which is rapidly melting glaciers around the world — is affecting the surge cycles.

Mark Fahnestock, a glaciologist at the University of Alaska Fairbanks, told the New York Times climate change means more melting and less ice accumulation. 

"There will be effects, especially in Alaska because the mass loss is so high," he said.

One of the GPS units placed on the Muldrow Glacier on March 28 to track the surge. (National Parks Service)

Landing on the glacier to install the equipment was no easy feat, Hults said. The crevassing meant there were few safe places to land. But it was well worth the effort to collect footage and data of the rare event.

"I was installing the first time-lapse camera near the top of the glacier when I heard this big ice crash," he said.  "I looked up and there was all this ice avalanching off the like 40-metres tall cliff right there. So it was pretty impressive to see that."

It was a far cry from the first time he visited Muldrow up close nearly 20 years ago when he was an intern for Denali National Park.

"One of my first projects up there was helping start some of the original baseline pre-surge studies. And so I was able to get out there on the glacier 20 years ago, standing on the glacier, walking all the way across the glacier," he said.

At the time, he said, the ice was smooth and unmoving.

"And to get back there, you know, 20 years later and look at this glacier that used to be just really stagnant and basically looked like a dying glacier, look like it's just a raging torrent going downhill, and massive crevassing and crashing ice and massive ice walls," he said.

"It's just a spectacular sight. It's so awe-inspiring to see it."


Written by Sheena Goodyear. Interview with Chad Hults produced by Chris Trowbridge.

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