Why this Alaska glacier is surging ahead of the others?

Two glaciers cascade off Denali. (Photo courtesy of the National Parks Service)

Geologic changes typically move slow. But one glacier in Denali National Park and Preserve could be moving at a decidedly un-glacial pace. Scientists think it’s doing something only a small amount of glaciers do, an event called “surging.”

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The Traleika glacier last surged around 60 years ago and experts think it’s on track to do it again.

“It’s just exciting to see the natural world rearing up and acting crazy. Doing big things,” Michael Loso said.

Loso is a physical scientist at Wrangell-St. Elias National Park. His work also takes him to Denali, where the glacier is showing signs of increased movement.

When a glacier’s ice flows downward at a relatively accelerated rate, that’s when it’s surging. It will start to flatten at the top with more ice moving towards the glacier’s lower end.

Ice flow speed is increasing on Traleika glacier, indicating a coming surge. (Photo courtesy of the National Parks Service)

Loso said, at the moment, you might not notice anything is different about the Traleika glacier.

“But if it develops into a full blown surge, the kind of behavior that we know it exhibited back in the 1950s,” Loso said. “You would see a glacier that was completely transformed from what is had looked like, say, a year before.”

Not all glaciers surge. In fact, Loso estimated that only a small percent in the world do. It’s something that scientists only partly understand.

And while climate change is causing Denali’s glaciers to shrink, Loso said surging is different. It’s more that the glacier is changing shape.

Loose sediment and flowing water have something to do with it, and Loso knows that the behavior happens in cycles. In Traleika’s case, scientists think it’s about every 60 years. The upper part of the glacier thickens, enough to start to move quickly.

I ask if planted a lawn chair down by the glacier and took a seat, would I actually be able to see it moving over time?

“If you sat with your lawn chair and brought a tent and just watched for a few days, you would see the difference,” Loso said. “You would see the changes. Absolutely.”

Loso sid that camping out by the glacier is kind of fanciful idea given the rugged terrain. He said scientists will be keeping a close eye on the Traleika glacier to see if it has a domino effect.

The last surge caused the Muldrow glacier, which is connected Traleika, to surge, too.

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