Icelandic Zombie Glacier Survives by Shedding Dead Bits

Posted by on Oct 28, 2014

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Falljökull glacier. Photo: © Matt Malone

Falljökull glacier. Photo: © Matt Malone

It’s alive! British scientists recently discovered that a glacier named Falljökull in Iceland, considered dead, is in fact partially “alive.” Using 3D imaging of the interior and surface of the glacier, they found that its long top section, which extends in a steep ice fall from the ice cap Öraefajökull to a plateau below, has at least temporarily saved itself by severing ties with a lower stagnant, dead piece. It brings to mind that lone hiker pinned under a rock who hacked off his arm a few years ago to escape certain demise in the wild.

Perched as it is between dead and undead, Falljökull has earned the nickname zombie glacier in the popular press. But it’s not clear whether this unusual glacier behavior of sloughing off dead ice–behavior that had never before been reported–will keep this patient alive over the long run. Today, the glacier’s active, or living, length is about 700 meters shorter than it was five years ago.

“It would be nice to think that the behaviour we have described at Falljökull could represent a type of ‘survival mechanism’ whereby steep mountain (Alpine) glaciers can quickly adapt to warming summer temperatures and decreasing snow fall during the winter months,” wrote Emrys Phillips, British Geological Survey research scientist and lead-author of the paper, in an email. But its survival ultimately depends on whether it remains “attached” to the Öraefajökull ice cap, its source, he said. And predicting how the glacier will behave in the future is tricky.

Consider snow and ice, and you may conjure barren, unforgiving landscapes that don’t sustain much life. But most glaciers are in some sense “alive,” an idea first proposed by legendary naturalist John Muir in the late 1800s. This means that the vast sheets, bulging tongues and glittering blue crowns of ice that constitute a glacier are mobile. They flow and advance in ice-rivers and ice-falls in winter and retreat in summer, according to seasonal patterns in snowfall and melt and given the pull of gravity that results when giant hunks of packed and frozen H2O are pitched at an alpine angle.

Of course, many glaciers are melting faster than they can accumulate new ice from snowfall, wind-blown snow, avalanches and frozen rain in the winter—mostly attributed to rising temperatures and increasing soot and dust in the atmosphere around the globe. This means the seasonal balance between advancing and retreating is thrown off, which can result in such a severe decline in glacier mass that the glacier is declared “dead.” A dead glacier stops moving and simply melts in place, like a giant ice cube in an empty glass on a hot day in summer.

The fault line where the living and dead pieces of the Falljökull glacier meet. "You can see the highly crevassed ice fall which feeds ice to Falljökull and then below that a ‘bulge’ in the glacier surface which is fractured and pocked marked by hollows – this area represents the living active part of the glacier. The thrust faults which are formed as the ice moves forward can be seen in the lower part of the glacier (the curved fractures cutting across the ice)," says British Geological Survey scientist Emrys Phillips. Photo Credit: British Geological Survey.

The fault line where the living and dead pieces of the Falljökull glacier meet. “You can see the highly crevassed ice fall which feeds ice to Falljökull and then below that a ‘bulge’ in the glacier surface which is fractured and pocked marked by hollows – this area represents the living active part of the glacier. The thrust faults which are formed as the ice moves forward can be seen in the lower part of the glacier (the curved fractures cutting across the ice),” says British Geological Survey scientist Emrys Phillips.
Photo Credit: British Geological Survey.

At Falljökull, the team of scientists, who published their research in the AGU Journal of Geogphysical Research in October, found that a new ice front has formed between living and dead pieces of the Falljökull glacier, with the living section actually surging up over the dead section into a bulge at a giant fault line. The scientists note that retreat of the original ice front has accelerated since 2007 and is moving at a faster rate than in any 5-year period since annual measurements began in 1932. Meanwhile, the upper part of Falljökull is still flowing forward at between 164 to 230 feet per year.

“Although the margin of Falljökull has ceased moving and is now undergoing stagnation, field and photographic evidences clearly show that the icefall remains active, feeding ice from the accumulation zone on Öraefajökull to the lower reaches of the glacier,” the scientists write in the paper. “To accommodate this continued forward motion, the upper section of the glacier below the icefall is undergoing intense deformation (folding and thrusting) and, as a result, is being thrust over the lower, immobile section of Falljökull.”

The group expects Falljökull is not the only glacier behaving in this manner, but finding out for sure will require more research. “As far as we know, this is the first time that this type of structural adjustment in active glacier length has been reported, so we cannot be certain that other mountain glaciers respond in the same way as Falljökull,” wrote Phillips. “But that said, from informal comments made by colleagues working in North America, Svalbard and elsewhere in Iceland, plus reading the published literature, we think that it is possible that a number of other Alpine-type glaciers are potentially behaving in a similar way.” In particular, they expect it may be found in places such as the Himalayas, Andes, Alps and Cascades.

The team of scientists was able to detect this zombie glacier behavior using Ground Penetrating Radar to map the ice’s internal structure; terrestrial Laser scanning (LiDAR) to create a 3D model of the surface of the glacier and surrounding landforms; four Global Navigation Satellite System stations on the glacier’s surface to record its velocity, and digital mapping and measuring of the glaciers surface structures, such as fractures, crevasses and faults.

 

Andrew Finlayson setting up the ground penetrating radar. Photo Credit: British Geological Survey.

Andrew Finlayson setting up the ground penetrating radar. Photo Credit: British Geological Survey.

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