Ten Cubic Kilometers of Ice Lost From Jakobshavn Glacier in Less than One Month

How large is a cubic kilometer? Think of something the size of a mountain. Now multiply that by ten and you end up with a veritable mountain range. Think of it. An entire mountain range of ice. That’s a good rough comparison to the volume of ice lost from just a single Greenland glacier over the course of a mere 26 days from May 7 to June 1 of 2014.

Jakobshavn Ibrae Ice loss 2014

(Massive ice loss from Jakobsbavn glacier captured by Espen Olsen. Image source: The Arctic Ice Blog.)

For according to reports from expert sea ice observer Espen over at the scientist and ice researcher camp that is Neven’s Arctic Ice Blog, about 7.5 square kilometers over an ice face about 1,300 meters tall (when including the above and below sea level ice front) shoved off from the great Jakobshavn Ibrae glacier during the past month. It was a period of time well before peak Greenland warming and one that featured a collapse of ice into the heating ocean even larger than the epic event caught on film during the seminal documentary Chasing Ice.

The Fastest Glacier in Greenland

Flowing at a speed of 46 meters per day, Jakobshavn is currently Greenland’s fastest glacier. Containing enough ice to raise global sea levels by 1.5 feet all by itself, the glacier is one of many of the Earth’s ice giants currently in the throes of irreversible decline.

Human-warmed subtropical Atlantic waters are funneled by ocean currents to the great glacier’s base. There, the high heat capacity does serious harm to the its weak underbelly, resulting in what is now an unprecedented seaward surge.

Since the 1990s, Jakobshavn’s forward rate of motion has tripled. But according to recent scientific reports, the glacier may just be at the start of an exponential spike in velocity. For as the glacier retreats it falls into a deepening chasm that exposes its front to greater and greater volumes of the warming ocean’s waters. The warm waters deliver more heat over the glacial face as it deepens even as a multiplication of melt lakes on the surface of the inland ice provide added lubrication and buoyancy to the ice base flowing into the chasm.

Greenland Bedrock Map

(Greenland map showing location of the Jakobshavn Glacier with close view of a deep channel in the bedrock. This channel was likely carved by previous discharge and at its deepest point is now more than 1,000 meters below sea level. Image source: NASA’s Earth Observatory.)

Estimates of energy transfer from the warming ocean show that Jakobshavn could reach a speed ten times 1990s values over the coming years. Ominously, the past two month’s immense calving event has shoved a large section of glacier closer to what could best be described as a high velocity melt chamber.

Greenland — An Archipelago Covered in Ice

Unfortunately, Jakobshavn is just one of Greenland’s many giant glaciers fronting deep and long chasms stretching far into the ice interior. Recent research from NASA’s Ice Bridge project revealed numerous deep rifts plunging for scores of miles into the ice sheet. The overall picture portrayed by the new study was that of an archipelago island system locked in the grip of two mile high ice mountains and riddled with deep bedrock canyons that join in a low-lying interior basin. A geography in which there is almost nowhere for ice to hide from the severe melting stress of Earth’s human-warmed oceans.

Due to this uniquely vulnerable topography lead Ice Bridge researcher Mathieu Morlighem, a UC Irvine associate project scientist concluded that:

“The glaciers of Greenland are likely to retreat faster and farther inland than anticipated – and for much longer – according to this very different topography we’ve discovered beneath the ice. This has major implications, because the glacier melt will contribute much more to rising seas around the globe.”

Human Warming Holds Numerous Large Glacial Collapses in Store

Under the current regime of human-caused climate change, the past month’s massive glacial release is likely only to be one of many. A single event of immense scale that defies imagining. Just one in an ongoing series of violent outbursts we’ve already set lose on our world.

An event of smaller, though still enormous, size was captured on film here:

(Largest glacial calving event captured on film as excerpted from the ground-breaking documentary ‘Chasing Ice.’)

It is a film that gives us some small measure of understanding of what we’ve done and what we continue to to do. For Greenland’s entire ice edge, a region unlocking ice twenty times the volume of Jakobshavn, is now in the process of deformation and collapse all while the massive glaciers of West Antarctica are also falling into irreversible release.

Links:

(Hat-tip to Colorado Bob)

The Arctic Ice Blog

Chasing Ice

NASA’s Earth Observatory

Greenland Will Be Far Greater Contributor to Sea Level Rise Than Expected

Greenland’s Jakobshavn Glacier Revs-up With Climate Change

Nature: Human Warming Now Pushing Entire Greenland Ice Sheet into the Ocean

Grim News From NASA: West Antartica’s Entire Flank Collapsing into Southern Ocean

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Doomed Pine Island Glacier Releases Guam-Sized Iceberg into Southern Ocean

Science has confirmed it. Human-caused warming is killing Antarctica’s massive Pine Island Glacier (PIG). And this week’s release of a chunk of ice larger than Guam into the southern ocean is just one of the many major losses that will occur as part of what is now an inevitable demise of one of the world’s greatest glaciers.

(CNN provides this stunning NASA imagery sequence of the break-off of B-31, a 12×24 mile iceberg from the, now doomed, Pine Island Glacier.)

Heat-Charged Blow to The Soft Underbelly of Antarctic Ice Shelves

As human greenhouse gas emissions caused the world’s oceans to warm, upwelling currents delivered a portion of that heat to the continental shelf zone surrounding Antarctica. A fortress of ice, numerous glacial ice shelves thrust out from this frozen land and drove deep into the sea floor. Ocean-fronting glaciers featured submerged sections hundreds of feet below the sea surface.

The warming currents encountered these massive ice faces, eroding their undersides and providing pathways for ocean waters to invade many miles beneath the glaciers. These invasions subjected the vulnerable ice shelves not only to the heat forcing of an ever-warming ocean, but also to wave and tidal stresses. The reduction in grounding and the constant variable stresses set the glaciers into a rapid seaward motion.

Antarctica’s most vulnerable glaciers lie along its western out-thrust. Two, Thwaites and the Pine Island Glacier, have recently seen very rapid increases in forward speed. Of these, the Pine Island Glacier, according to a recent study, is undergoing the process of an irreversible collapse. What this means is that the glacier’s speed of forward motion is now too great to be halted. Inevitably, even if the climate were to cool, the entire giant glacier will be launched into the world’s oceans where it will entirely melt out.

PIG basal melt

(Pine Island Glacier underwater melt dynamics. Image source: Nature)

Guam-Sized Chunk of Ice to be One of Many

The Pine Island Glacier is massive, covering a total area of 68,000 square miles and, in some locations, rising to over 2,000 feet in height. It represents 10% of all the ice in the West Antarctic Ice Sheet, holding enough liquid water to raise sea levels by between 1 and 2.5 feet all on its own. And the now destabilized PIG is bound to put added stresses on the adjacent Thwaites glacier together with almost the entire West Antarctic ice system.

Over recent years, PIG’s forward speed has accelerated. Increasing forward velocity by 73 percent from 1974 to 2007. Surveys made since that time show an even more rapid pace. By January of this year, studies were finding that PIG had entered a sate of irreversible collapse. So it is little wonder that enormous chunks of ice are breaking off from this massive glacier and drifting on out into the Southern Ocean.

As of early this week, the immense ice island dubbed B31 measuring 12×24 miles in size (nearly 290 square miles), slid off its temporary grounding on the sea bottom and began its journey out into the Southern Ocean. There it will remain for years, plaguing the world’s shipping lanes as it slowly disintegrates into a flotilla of icebergs. It is just the most recent event in the now ongoing decline of PIG. And we can expect many, many more major ice releases as this vast Antarctic glacier continues its dive to the sea.

Links:

Humongous Iceberg Slowly Drifts Away From Antarctica

Scientists: Warming Ocean, Upwelling Make an End to Antarctica’s Vast Pine Island Glacier

Nature

Retreat of Pine Island Glacier Controlled by Marine Ice Sheet Instability

The Pine Island Glacier

The Thwaites Glacier

Hat tip to Colorado Bob who’s been tracking PIG since 1994

 

 

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