Two of Greenland’s largest glaciers that flow to lower elevations and to the ocean are waxing and waning rapidly, researchers reported last week, suggesting that the effects of global warming on sea levels might be difficult to predict.
The study – based on satellite data and conducted by scientists at the University of Washington and the University of Colorado – found great fluctuations in the rate of ice discharge and mass loss from the two glaciers. The glaciers’ rate of mass loss doubled in less than a year in 2004 but then dropped in 2006 to close to previous rates.
“The synchronous and multi-regional scale of this change, and the recent change in Arctic air and ocean temperatures, suggest that these changes are due to climate warming,” wrote the authors, led by Ian Howat, a research associate at the University of Washington’s Polar Ice Center. “The possibility that ice dynamics are so highly sensitive to climate change is of concern, because the physical processes that would drive such a relationship … are not realistically included in ice sheet models used to predict rates of sea-level rise.” The researchers wrote in last week’s issue of Science that while it is difficult to predict how the glaciers will fluctuate in the future, “continued warming may cause a long-term drawdown of the ice sheet through a series of such discharge anomalies, perhaps with a similar degree of variability.”
