Image via University of California, Los Angeles
If the entire Greenland ice sheet, which covers 656,000 square miles, were to melt, it would pour enough water into the world's oceans to raise global sea levels by about 20 feet. But little is understood about how this massive hulk of ice behaves.A group of researchers spent five years measuring and imaging the flow of meltwater across the surface of the ice sheet. They found that each river of meltwater ended in a moulin, a kind of sink hole that allows the water to penetrate into the glacier and drain out at the bottom. The surface of the ice sheet, in other words, acts a bit like Swiss cheese."One of the most pressing environmental problems of the decades and centuries ahead is rising global sea levels, and one of the leading causes of sea level rise is the melting of ice from glaciers and ice sheets," Laurence Smith, chair of the UCLA geography department and lead author on the research, says. "Greenland in particular is the single largest melting chunk of ice in the world."In order to monitor the flow of meltwater, Smith and 10 other researchers launched buoys with on-board GPS devices and an unmanned boat designed at NASA's Jet Propulsion Laboratory. They also used military-grade satellite technology to take high-resolution images of the ice sheet's network of streams.Their findings, published Tuesday in the Proceedings of National Academy of Sciences, improve understanding of just how melting glaciers and ice sheets contribute to sea-level rise, which could help to better project how fast and how high the oceans will rise in the coming decades and centuries."If we can get better estimates, then we can have better projections for the extent and the impact of global warming," said Marco Tedesco, a co-author and head of City College of New York's Cryospheric Processes Laboratory. "Greenland is really the big player for sea-level rise in the future, so improving climate models is extremely crucial."Follow Laura Dattaro on Twitter: @ldattaro
Advertisement