New study and coordinated video simulation show ice loss migration in Greenland for the first time.
Greenland’s ice mass loss over the past decade–concentrated primarily over its southern most regions–has been well-documented and has been a prime impetus for global warming and climate change concerns, especially as regards the impacts on the Arctic region. Now, thanks to an innovative, combined Earth-Space monitoring system, geophysicists and climatologists have been able to track Greenland’s ice mass loss “migrating” northward (see the embedded video simulation of this migration in the body of this article).
According to a recently published paper in the journal Geophysical Research Letters (Khan et al), Greenland’s ice mass loss has been accelerating and is now spreading up along its northwest coast, with data indicating the start of this acceleration to be late 2005.
In the Sky and On the Ground – Dual Data Sources Track Ice Loss
Compelling evidence for this conclusion comes from two sources: measurements from the Gravity Recovery and Climate Experiment (GRACE), a dual-satellite gravity mission (launched in March 2002), and, continuous Global Positioning System (GPS) measurements from three sites on bedrock adjacent to the ice sheet. Data from the two GRACE satellites provide direct measurements of ice mass loss averaged over several hundred kilometers. Data from the long-term GPS sites measures “crustal uplift” which results from the lessening of heavy ice sheet covering. The GRACE measurements of subtle changes in the Earth’s gravitational field were used to predict this crustal uplift phenomenon and then compared to the GPS data.
The results of this combined Earth-Space monitoring system show Greenland’s northwestern ice sheet margin now losing mass, and further, the data show rapid ice mass loss in southeastern Greenland, starting in 2003 (note: there was a brief period of moderate deceleration of ice mass loss in 2006, but this change was “weak”, and total loss is now increasing at a higher rate than before 2003).
This is this first time that this phenomenon (i.e., crustal uplift) has been documented. The team speculates that some of the big glaciers in this region (northwest) are sliding downhill faster and dumping more ice into the oceans. Quoting from the paper: “Greenland’s main outlet glaciers have more than doubled their contribution to global sea level rise over the last decade.”
View the simulation of Greenland’s spreading ice mass loss since 2003:
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Led by Danish geophysicist Shfaqat Abbas Khan of the National Space Institute in Copenhagen, Denmark, the analysis team included four US scientists: John Wahr (Department of Physics and Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder), Michael Bevis (School of Earth Sciences, Ohio State University), Isabella Velicogna (Department of Earth System Science, University of California, Irvine and Jet Propulsion Laboratory, California Institute of Technology), and Eric Kendrick (School of Earth Sciences, Ohio State University)
This unique analytical approach to Earth monitoring–apart from proving that such satellite measurements can be used to measure crustal uplift–has aided better understanding of Greenland’s loss of ice mass, and will prove enormously useful to future, long-term data analyses. This will be born out in large part due to the recent establishment of GNET (Greenland GPS Network), comprised of 51 permanent GPS stations around the edge of the ice sheet .
Image Credit: American Geophysical Union
Video Simulation: courtesy of John Wahr, Univ. of Colorado at Boulder