This Alaskan Glacier is Moving 100 Times Faster Than Normal

Denali National Park's Muldrow Glacier is Surging

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K2 Aviation runs scenic flights around Denali, America’s highest point at 20,310 feet, and transports aspiring summiters to basecamp. On a routine flight in early March this year, pilot Chris Palm noticed something unusual on the flanks of the mountain. The normally uniform Muldrow Glacier was sliced and diced with exceptionally large cracks and crevasses. Not in one spot, but everywhere. The glacier looked like it was falling apart. 

The Muldrow is a 39-mile long glacier that starts high on the northeastern slope of Denali and flows into the McKinley River. It’s one of four main routes to the summit (the others are the West Buttress, West Rib, and Cassin Ridge), and for the last 60 years, it has flowed downhill at a rate of 3 to 11 inches per day. It’s now moving at a blistering pace (for a glacier) of 30 to 60 feet per day, or up to 100 times faster than usual. 


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You’d be excused for thinking this is just another one of the symptoms of our warming planet. Surprisingly, scientists say, you’d be wrong: It’s a relatively rare phenomenon known as glacial surge. 

This phenomenon is a well known, though not well understood, event in the life of some glaciers (roughly 1 percent of the Earth’s glaciers surge). After periods of slow, unremarkable flow (or quiescence) lasting 10 to 200 years, a combination of factors results in the gravitational force driving the glacier downhill exceeding the friction at the base of the ice. Subglacial meltwater often acts as a lubricant, causing the glacier to move faster. The increased velocity creates heat, which melts more ice into water. Theories as to why this occurs range from poorly consolidated rock beneath the flow to “critical mass,” when the ice reaches the maximum weight the topography can hold before it simply has to slide due to basal melting. Alaska is one of the few areas of the world where glacial surge is consistently observed, usually with a sudden onset. The other areas are the Karakorum, the Pamir Mountains, and Svalbard, a Norwegian Archipelago. 

The National Park Service is studying the Muldrow and has an extremely detailed analysis.


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So, what does this mean for you? If you were planning on climbing Denali this season (and perhaps next) via the Muldrow Glacier, it’s probably best to consider other options. If not, don’t add this to your list of worries but to your list of little-known glacier facts instead. 

A Few More Glacier Facts

Alaska has more than 100,000 glaciers.

Glacier ice is the largest freshwater reservoir on the planet, holding an estimated 70-75% of the world’s supply. 

47 countries have glaciers. 

The most heavily glaciated peak in the Lower 48 is Mt. Rainier with 25. 

The largest glacier on earth is the Lambert Glacier in Antarctica at 50 miles wide and 270 miles long