Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Team advances understanding of the Greenland Ice Sheet’s meltwater channels

02.10.2014

An international research team’s field work is showing that, well, things are more complicated than we thought.

An international research team’s field work, drilling and measuring melt rates and ice sheet movement in Greenland is showing that things are, in fact, more complicated than we thought.


An international team of researchers deployed to western Greenland to study the melt rates of the Greenland Ice Sheet.

“Although the Greenland Ice Sheet initially speeds up each summer in its slow-motion race to the sea, the network of meltwater channels beneath the sheet is not necessarily forming the slushy racetrack that had been previously considered,” said Matthew Hoffman, a Los Alamos National Laboratory scientist on the project.

A high-profile paper appearing in Nature this week notes that observations of moulins (vertical conduits connecting water on top of the glacier down to the bed of the ice sheet) and boreholes in Greenland show that subglacial channels ameliorate the speedup caused by water delivery to the base of the ice sheet in the short term. By mid summer, however, the channels stabilize and are unable to grow any larger.

In a previous paper appearing in Science, researchers had posited that the undersheet channels were not even a consideration in Greenland, but as happens in the science world, more data fills in the complex mosaic of facts and clarifies the evolution of the meltwater flow rates over the seasons.

In reality, these two papers are not inconsistent - they are studying different places at different times - and they both are consistent in that channelization is less important than previously assumed, said Hoffman.

The Greenland Ice Sheet’s movement speeds up each summer as melt from the surface penetrates kilometer-thick ice through moulins, lubricating the bed of the ice sheet. Greater melt is predicted for Greenland in the future, but its impact on ice sheet flux and associated sea level rise is uncertain: direct observations of the subglacial drainage system are lacking and its evolution over the melt season is poorly understood.

“Everyone wants to know what’s happening under Greenland as it experiences more and more melt,” said study coauthor Ginny Catania, a research scientist at the institute and an associate professor in the University of Texas at Austin’s Jackson School of Geosciences. “This subglacial plumbing may or may not be critical for sea level rise in the next 100 years, but we don’t really know until we fully understand it.”

To resolve these unknowns, the research team drilled and instrumented 13 boreholes through 700-meter thick ice in west Greenland. There they performed the first combined  analysis of Greenland ice velocity and water pressure in moulins and boreholes, and they determined that moulin water pressure does not lower over the latter half of the melt season, indicating a limited role of high-efficiency channels in subglacial drainage.

Instead they found that boreholes monitor a hydraulically isolated region of the bed, but decreasing water pressure seen in some boreholes can explain the decreasing ice velocity seen over the melt season.

“Like loosening the seal of a bathtub drain, the hydrologic changes that occur each summer may cause isolated pockets of pressurized water to slowly drain out from under the ice sheet, resulting in more friction,” said Hoffman.

Their observations identify a previously unrecognized role of changes in hydraulically isolated regions of the bed in controlling evolution of subglacial drainage over summer. Understanding this process will be crucial for predicting the effect of increasing melt on summer speedup and associated autumn slowdown of the ice sheet into the future.

The research letter is published in this week’s Nature magazine as “Direct observations of evolving subglacial drainage beneath the Greenland Ice Sheet.” The project was an international collaboration between the University of Texas at Austin, Los Alamos National Laboratory, NASA Goddard Space Flight Center, Michigan Technological University, University of Zurich, the Swiss Federal Institute of Technology and Dartmouth College.

This project was supported by United States National Science Foundation, the Swiss National Science Foundation and the National Geographic Society. The work at Los Alamos was supported by NASA Cryospheric Sciences, and through climate modeling programs within the US Department of Energy, Office of Science.

Also see "Geoscience: The plumbing of Greenland's ice."

About Los Alamos National Laboratory
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and URS for the Department of Energy's National Nuclear Security Administration.

Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.

Nancy Ambrosiano | Eurek Alert!
Further information:
http://www.lanl.gov/discover/news-release-archive/2014/October/10.01-greenlands-ice-sheets.php

More articles from Earth Sciences:

nachricht NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center

nachricht The melting ice makes the sea around Greenland less saline
16.10.2017 | Aarhus University

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Researchers release the brakes on the immune system

18.10.2017 | Health and Medicine

Separating methane and CO2 will become more efficient

18.10.2017 | Life Sciences

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>