New study finds ice decreasing on northwest coast of Greenland

In the past decade, Greenland has been losing ice in its southern region. Now that ice loss is moving up Greenland’s northwest coast, according to a new international study.

This ice loss started in 2005 say these scientists, who are from the Denmark Technical Institute’s National Space Institute in Copenhagen and the University of Colorado at Boulder.

“Our results show that the ice loss, which has been well documented over southern portions of Greenland, is now spreading up along the northwest coast,” said Shfaqat Abbas Khan, lead author on a paper that will appear in Geophysical Research Letters.

Click here to read the full press release about this recent study and watch a video of a Greenland ice melt simulation.

How do these scientists know the ice is decreasing? Here’s what the press release says: “The team drew their conclusions by comparing data from NASA’s Gravity and Recovery Climate Experiment satellite system, or GRACE, with continuous GPS measurements made from long-term sites on bedrock on the edges of the ice sheet.”

Sometimes it seems as if people believe that there’s a big Earth book out there, and scientists simply read it to find all the answers. But it isn’t simple. The book is Earth itself, the chapters aren’t in order, there’s no index, and the story is being told in thousands of different languages by rocks and ice and air and water.

So Earth’s scientists – our scientists – have to do what they can with the tools they have to study Earth and its changes. In this case, the tools are both housed on satellites orbiting Earth. These scientists used data from the Global Positioning System (GPS) satellites and the orbiting twin GRACE satellites. These scientists were able to get monthly averages of “crustal uplift,” in other words, how much the body of Greenland itself was rising up as the weight of ice resting on it melted into the surrounding sea. GRACE measured uplift over chunks of Greenland the size of the United Kingdom. Meanwhile, the GPS receivers monitor crustal uplift on scales of just tens of miles. If it all sounds hard to analyze, well, that’s why scientists study for years – devote their lives – to understanding how to do this work.

Wikipedia says that Greenland is, by area, the world’s largest island that is not a continent. Ice covers 80% of its surface. Greenland is the least densely populated country in the world, by the way. It’s largest city and capital is Nuuk (population 17,834 in January 2009), which is in southwestern Greenland and about 150 mile south of the Arctic Circle. I just found that interesting.

More fun facts. No one is saying Greenland’s ice is going to melt entirely. But, also according to Wikipedia, the bedrock in the center of Greenland has been pressed below sea level by the weight of the ice sheet. So if all the ice in Greenland did melt, much of central Greenland would be under water.

In fact, Greenland holds about 20 percent of the world’s ice, the equivalent of about 21 feet of global sea rise. Air temperatures over the Greenland ice sheet have increased by about 4 degrees Fahrenheit since 1991, which most climate scientists – those guys who have studied for years to do this work – attribute to a build-up of greenhouse gases in the atmosphere.

A 2009 study showed that between April 2002 and February 2009, the Greenland ice sheet shed roughly 385 cubic miles of ice. The mass loss is equivalent to about 0.5 millimeters of global sea-level rise per year.

A 2006 study indicated that Greenland lost roughly 164 cubic miles of ice from April 2004 to April 2006 – more than the volume of water in Lake Erie.

What does it all mean? One of the researchers commented, “These changes on the Greenland ice sheet are happening fast, and we are definitely losing more ice mass than we had anticipated. “

March 23, 2010

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