Coastal infrastructuresRivers of meltwater on Greenland’s ice sheet contribute to rising sea levels
As the largest single chunk of melting snow and ice in the world, the massive ice sheet that covers about 80 percent of Greenland is recognized as the biggest potential contributor to rising sea levels due to glacial meltwater. Until now, however, scientists’ attention has mostly focused on the ice sheet’s aquamarine lakes — bodies of meltwater that tend to abruptly drain — and on monster chunks of ice that slide into the ocean to become icebergs. A new study reveals, however, a vast network of little-understood rivers and streams flowing on top of the ice sheet that could be responsible for at least as much, if not more, sea-level rise as the other two sources combined.
As the largest single chunk of melting snow and ice in the world, the massive ice sheet that covers about 80 percent of Greenland is recognized as the biggest potential contributor to rising sea levels due to glacial meltwater.
Until now, however, scientists’ attention has mostly focused on the ice sheet’s aquamarine lakes — bodies of meltwater that tend to abruptly drain — and on monster chunks of ice that slide into the ocean to become icebergs.
A UCLA release reports that a new UCLA-led study reveals, however, a vast network of little-understood rivers and streams flowing on top of the ice sheet that could be responsible for at least as much, if not more, sea-level rise as the other two sources combined.
When snow and ice thaw during the summer, these waterways form an intricate drainage system that captures virtually all surface runoff and is capable of flushing its entire volume in less than two days, the team found.
“It’s the world’s biggest water park, with magnificent and beautiful — but deadly — rushing blue rivers cutting canyons into the ice,” said Laurence C. Smith, the study’s lead author and the chair of UCLA’s geography department.
The research, published in the latest issue of Proceedings of the National Academy of Sciences, highlights the fragility of the ice sheet as well as the amount of havoc it could create as global warming progresses.
With funding from NASA’s Cryospheric Sciences program, eleven researchers — three of them UCLA graduate students — spent six days during July 2012, gathering measurements in an environment so hostile and dangerous that no such effort had ever been attempted.
Because the ice sheet was so unsteady and the amount of territory they covered was so great, researchers moved around by helicopter. To map the network and compute the rivers’ flow rates, they used military-grade satellite imagery, buoys outfitted with GPS technology and a drone boat specially designed for the project by a Jet Propulsion Laboratory engineer who also worked on the Mars Rover.
The study happened to coincide with a massive and extremely unusual melt. On only one other occasion in the past 700 years — in 1889 — has the ice sheet thawed as much as it did in 2012.
“It was a real preview of just how quickly that ice sheet can melt and the meltwater can escape,” Smith said.
