While drastic increases in ice melt around Greenland have been detected in recent years, some parts of the region’s ice sheet have been found to be less vulnerable to climate change than was previously believed, claims new research published this week in the journal Nature.
The discovery, made by an international team of scientists including Edward Hanna, a professor of geography from the University of Sheffield in the UK, was made using computer models and satellite imagery. It could have a minor but positive impact on sea level forecasts, they said.
In some areas of the Greenland ice sheet, the speed of ice movement has actually slowed down instead of accelerating, the study authors explained. Large quantities of meltwater in the summer produces channels at the ice sheet’s base, efficiently draining away water and reducing the speed of the glacier’s movement the following winter.
“Our research underscores the complexity of the relation between climate change affecting Greenland and the response of its ice sheet to the ongoing warming,” said Hanna. “We need to understand these ice-climate interactions better in order to be able to make more reliable global sea-level predictions.”
Additional melting could slow down these areas even more
Contrary to what some may believe, more meltwater does not always necessarily result in ice flowing more quickly, Hanna explained. Observations made on a portion of the ice sheet that ends on land instead of on the water indicated that increased volume of icemelt does not necessarily speed up the entire sheet’s motion by causing it to slide more rapidly.
Instead, their study shows that over the past few decades, ice movement in select portions of the ice sheet that terminate on land have actually slowed down, not sped up. Furthermore, the study indicates that additional increases in ice melting resulting from warming temperatures may even further slow down the movement of these areas.
Hanna and his colleagues used satellite data to track the shift of crevasses and other ice features over a 30 year span, and found that even though meltwater had increased by 50 percent over the past few years, the overall movement during the last decade was slower than it was over the last few decades. More research is needed to fully understand the movement of parts of the ice sheet that terminate in the ocean and have experienced acceleration recently, they added.
“A large sector of the Greenland ice sheet has slowed down, despite sustained warming in the past decade,” said lead investigator Andrew Tedstone from the University of Edinburgh’s School of GeoSciences. “However, the ice sheet’s overall contribution to sea level rise continues to accelerate in two ways: through increases in surface melting and the movement of glaciers which terminate in the ocean.”
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Image credit: Thinkstock
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