Giant Ice Island Breaks Off Greenland Glacier

August 10, 2010
Scientists report that an ice island four times as big as Manhattan has broken off one of Greenland’s Petermann Glacier, and is now floating through the waters that separate Greenland and Canada.  It’s the largest piece of ice to break away from Greenland’s two main glacier’s in almost 50 years, and comes at a time when Arctic ice cover is steadily retreating and glaciers at both the world’s poles are growing smaller. 
While damage to any one glacier can never be attributed with certainty to global warming, the increasing frequency of events like this certainly are suggestive that a warming climate is causing irreversible damage to polar ecosystems.
On Thursday, about one fourth of the Petermann Glacier’s floating ice shelf broke away and fell into the ocean.  The resultant floating island of ice is 600 feet thick, and with a surface area of around 100 square miles.  If a chunk of ice this big were melted down, it would be enough to supply the entire United States with drinking water for 120 days.  Yet Thursday was just the latest and most dramatic example of a growing trend in the arctic. 
Just last month another large ice chunk, this one about 2.7 square miles across, broke off of Greenland as well.  The July event pushed the edge of Greenland’s ice shelf further inland than at any known time in history.  Similarly in 2008 a ten-square-mile ice island broke away from the Petermann Glacier, and in 2001 a 34-square-mile piece broke off.  Though glacier “calving” is a natural phenomenon, it is very likely global warming will continue to increase the frequency of such events in the future.  Scientists are watching the new ice island off of Greenland to see if it will fuse to some land mass, break up into smaller pieces, or perhaps interfere with ocean shipping routes. 
As Arctic temperatures have warmed over the last decade, melting ice has formed pools of water on the surface of Greenland’s glaciers.  This liquid water absorbs more heat from the sun than ice does, and this contributes to further warming and even more ice melting.  Eventually liquid water seeps into cracks in the ice, and lubricates the movement of massive glaciers.  Scientists believe this has contributed to Arctic glaciers migrating toward the ocean more quickly, at last falling into the sea or forcing partially submerged ice flows to break away.  If all of Greenland’s ice melted it could cause sea levels around the world to rise by as much as 23 feet, endangering major cities like Los Angeles that are located a short distance from the coast. 
Meanwhile on the other side of the planet, ice in Antarctica is also breaking up or melting.  In 2002 a massive piece of the Larsen B ice shelf in Antarctica collapsed into the ocean, and in 2006 climate scientists announced global warming was almost certainly one of the causes of the breakup.  Both the Arctic and Antarctica appear to be feeling the effects of a changing climate sooner than many other parts of the globe, providing a glimpse of what a warming world might look like.
Like elsewhere on the planet, climatic shifts at the Earth’s poles are influenced by many factors, some of which have nothing to do with human activity.  Yet the frequency of large ice breakaway events from over the last ten years is striking, and certainly consistent with the idea that global warming will result in reduced ice packs around the world.
Photo credits: Rita Willaert, Thomas Pix

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