Subscribe free to our newsletters via your
. Space Travel News .

A check on runaway lake drainage
by Staff Writers
Boston MA (SPX) Jun 09, 2015

A water-filled hydro-fracture and ice blocks remain after a supraglacial lake drained on Greenland's ice sheet in 2011. Image courtesy Ian Joughin.

Each summer, Greenland's ice sheet - the world's second-largest expanse of ice, measuring three times the size of Texas - begins to melt. Pockets of melting ice form hundreds of large, 'supraglacial' lakes on the surface of the ice. Many of these lakes drain through cracks and crevasses in the ice sheet, creating a liquid layer over which massive chunks of ice can slide. This natural conveyor belt can speed ice toward the coast, where it eventually falls off into the sea.

In recent years, scientists have observed more lakes forming toward the center of the ice sheet - a region that had been previously too cold to melt enough ice for lakes to form. The expanding range of lakes has led scientists to wonder whether Greenland will ultimately raise global sea levels higher than previously predicted.

Now researchers at MIT, Woods Hole Oceanographic Institution (WHOI), and elsewhere have found that while warming temperatures are creating more inland lakes, these lakes cannot drain their water locally, as lakes along the coast do, and are not likely to change the amount of water reaching the ground in inland regions.

'It's essentially a check on the inner ice starting to move along this fast conveyor belt,' says Laura Stevens, a graduate student in MIT's Department of Earth, Atmospheric and Planetary Sciences. 'One of the big questions about the Greenland ice sheet is how much of the ice sheet [travels towards the coast] during the summer, and how much is entering into the ocean. Our hypothesis that inland lakes are less likely to drain locally suggests the ice sheet in that region won't speed up. That's good news, at least for the time being.'

Stevens and her colleagues, including Thomas Herring, a professor of geophysics at MIT, have published their results in the journal Nature.

A trickle and a trigger
In summer 2006, Sarah Das, a glaciologist at WHOI, led a team to document the drainage of North Lake, a 10-meter-deep, 2-kilometer-wide lake on the western side of Greenland. The group observed that each summer, the lake, like many others, drained quickly, completely emptying in just a couple of hours.

'You can hear the water rushing down in the distance, and even if you're a couple kilometers away, you see all these microcracks running along the ground around you,' Stevens says.

The researchers set up one GPS station near the lake to record the surface of the ice during its draining, and later identified a large fracture in the basin through which the water drained. However, it wasn't clear what triggered the fracture that caused the lake to drain so quickly.

Das returned to Greenland in summer 2011, along with Stevens and others, to get a more detailed picture of the lake's seasonal draining. The team set up 16 GPS stations in two rings around the lake, and recorded the movement of the ice as the lake drained once each summer over three consecutive summers.

From the GPS data, they observed a period of six to 12 hours, just before the lake drained, in which some water from the lake trickled to the bottom of the ice sheet through 'moulins' - narrow vertical channels in the ice. During this brief period, the researchers observed water collecting at the bottom of the ice sheet, pushing up on the surface ice. This initial pooling of water seemed to trigger the rest of the lake to drain.

'That water will cause the ice above it to be jacked up like a dome, and then you've created tension at the surface that allows the ice sheet to start to fracture,' Stevens says. 'Once a fracture gets beneath the lake, then water just starts to pour into that fracture, and the whole thing goes.'

A check on runaway lake drainage
North Lake is located within the coastal region of Greenland, where the ice sheet is thinner, and more moulins route water at the surface of the ice sheet to its base.

In contrast, lakes further inland are higher in elevation and form over thicker ice. Stevens says it's unlikely that inland lakes would drain, as there are fewer moulins near inland lakes, which prevents water from getting to the ground locally. Without these trigger channels, larger fractures would not form in the lake basin, and lakes would stay intact, simply refreezing in the winter or overflowing into a surface stream.

'It is critical to understand how and why these lakes drain in order to predict how much mass the ice sheet will contribute to sea-level rise in our warming climate,' Stevens says.

'We find that while lakes are forming inland, they probably won't drain by this...mechanism. The inland lakes will more likely drain their water via surface stream runoff, which transfers the water to the bed in more coastal areas of the ice sheet. So, while we see inland ice beginning to speed up as more melt happens inland, the draining of inland lakes likely won't exacerbate the situation.'

Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Contributor
$5 Billed Once

credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly

paypal only


Related Links
Massachusetts Institute of Technology
Water News - Science, Technology and Politics

Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks DiggDigg RedditReddit GoogleGoogle

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Sudden draining of glacial lakes explained
Woods Hole MA (SPX) Jun 09, 2015
In 2008 scientists from Woods Hole Oceanographic Institution (WHOI) and the University of Washington documented for the first time how the icy bottoms of lakes atop the Greenland Ice Sheet can crack open suddenly--draining the lakes completely within hours and sending torrents of water to the base of the ice sheet thousands of feet below. Now they have found a surprising mechanism that triggers ... read more

Airbus developing reusable space rocket launcher

Recent Proton loss to push up launch costs warns manufacturer

Air Force Certifies SpaceX for National Security Space Missions

SpaceX cleared for US military launches

NASA Spacecraft Detects Impact Glass on Surface of Mars

Building a Smarter Rover

Mars Missions to Pause Commanding in June, Due to Sun

United Arab Emirates Hopes to Reach Mars by2021

Crashing comets may explain mysterious lunar swirls

Google Lunar X-Prize meets Yoda

China, Russia plan joint landing on the Moon

NASA's LRO Moves Closer to the Lunar Surface

Pluto probably a binary planet with largest moon Charon

Hubble finds Pluto's moons tumbling in absolute chaos

New Horizons team completes first search for Pluto system hazards

New Horizons sees more detail as it draws closer to Pluto

Hubble in 'Oh Planet, What Art Thou?' 25th Anniversary Video

Astronomers discover a young solar system around a nearby star

Astronomers Discover a Young Solar System Around a Nearby Star

Circular orbits identified for small exoplanets

US space firm supports need to ease Russian rocket engines ban

Launch Vehicle Rocket Engines

NASA Looks to Cut Travel Time to Mars in Half with Superfast Propulsion

US Air Force Launches Competition to Replace Russian Rocket Engines

China Plans First Ever Landing On The Lunar Far Side

China ranked 4th among world space powers

3D printer making Chinese space suit parts

Xinhua Insight: How China joins space club?

Alice's UV close-up provides a surprising discovery about comet's atmosphere

Ultraviolet study reveals surprises in comet coma

NASA Instrument on Rosetta Makes Comet Atmosphere Discovery

Dawn seeking greater riches as second orbit of Ceres begins

The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.