August 3, 2012
Greenland’s Rapid Ice Sheet Recession Difficult To Predict
Brett Smith for redOrbit.com - Your Universe Online
Despite the rapid thaw of the Greenland Ice Sheet, scientists are still far from even being able to predict its disappearance. Recent research conducted by an international team of scientists provided evidence that this is not the first time in modern history that the ice sheet has receded and then stabilized again.Research and news reports surrounding the melting of polar and sub-polar ice often has a doom and gloom tone, but the recent findings by a University of Copenhagen team of scientists shows that the Greenland Ice Sheet is more stout than many researchers have previously predicted, according to their report published this week in the journal Science.
Instead of relying on computer models, the new research findings were obtained by analyzing contemporary satellite data and old aerial photographs of the ice sheet in northwestern Greenland, which is well known for its thinning ice sheet and heavy melting.
"Over the past three years a number of scientific articles have addressed the issue and pointed to a sea-level rise of one meter or more,” explained study co-author and University of Copenhagen professor Kurt H. KjÃ¦r.
“These reports presuppose that the melting will accelerate to the same degree as during the past decade. This is a question to which we have been able to provide a qualified answer. It turns out that the ice sheet, in relation to this point, behaves more dynamically and is able to more quickly stabilize itself in comparison to what many other models and computer calculations otherwise predict."
To analyze the condition of the ice sheet over the past 30 years, researchers constructed a digital elevation map based on aerial photographs from the 1980's and satellite imagery. They found that despite a significant thinning along the edges of the ice sheet from 1985-1992–the melting slowed and then stopped altogether, according to the researchers.
KjÃ¦r also noted that the Greenland bedrock rises as the peripheral and coastal sections of the ice sheet retreat, reinforcing the idea of just how difficult it is to calculate and predict the activity of the Greenland Ice Sheet.
"Our results show that the thinning of the ice sheet at the end of the 80's and beginning of the 90's eased over a 4-8 year period, after which a period of stability occurred until 2003,” KjÃ¦r said. “Our conclusion is therefore, that if we judged against longer periods of time, the current thinning of the ice sheet is likely to ease within an 8-year period."
"These variations in the amount of thinning that we are able to document since the 80's make it difficult to predict how much the world's oceans will rise over a longer period of time - a century for instance - as a result of Greenland glacial melt-water runoff,” he added.
“However, it is certain that many of the present calculations and computer models of ice sheet conditions that built upon a short range of years since 2000 must be reassessed. It is too early to proclaim the 'ice sheet's future doom' and subsequent contribution to serious water problems for the world.”