Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New study indicates loss of West Antarctic glaciers appears unstoppable

14.05.2014

A new study finds a rapidly melting section of the West Antarctic Ice Sheet appears to be in an irreversible state of decline, with nothing to stop the glaciers in this area from melting into the sea.

The study presents multiple lines of evidence, incorporating 40 years of observations that indicate the glaciers in the Amundsen Sea sector of West Antarctica “have passed the point of no return,” according to glaciologist and lead author Eric Rignot, of the University of California Irvine and NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. The new study has been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union.


A photograph of Thwaites glacier in West Antarctica taken by NASA’s Operation IceBridge. A new study finds a rapidly melting section of the West Antarctic Ice Sheet appears to be in an irreversible state of decline, with nothing to stop the glaciers in this area from melting into the sea.

Credit: NASA


The Amundsen Sea glacier beds are below sea level, so that as the grounding lines retreat, the water below the floating ice shelves gets deeper rather than shallower. This image shows the beds of Thwaites and Haynes glaciers, with colors indicating depth. The large blue area under Thwaites Glacier is almost three-quarters of a mile (1,200 meters) below sea level. The broken lines at the front of the glacier show how the grounding line has retreated over 19 years; red is the 1992 grounding line, and black is the line’s position in 2011.

Credit: NASA

These glaciers already contribute significantly to sea level rise, releasing almost as much ice into the ocean annually as the entire Greenland Ice Sheet. They contain enough ice to raise global sea level by 4 feet (1.2 meters) and are melting faster than most scientists had expected. Rignot said these findings will require an upward revision to current predictions of sea level rise.

“This sector will be a major contributor to sea level rise in the decades and centuries to come,” Rignot said. “A conservative estimate is it could take several centuries for all of the ice to flow into the sea.”

Three major lines of evidence point to the glaciers’ eventual demise: the changes in their flow speeds, how much of each glacier floats on seawater, and the slope of the terrain they are flowing over and its depth below sea level. In a paper published in Geophysical Research Letters in April, Rignot’s research group discussed the steadily increasing flow speeds of these glaciers over the past 40 years. This new study examines the other two lines of evidence.

The glaciers flow out from land to the ocean, with their leading edges afloat on the seawater. The point on a glacier where it first loses contact with land is called the grounding line. Nearly all glacier melt occurs on the underside of the glacier beyond the grounding line, on the section floating on seawater.

Just as a grounded boat can float again on shallow water if it is made lighter, a glacier can float over an area where it used to be grounded if it becomes lighter, which it does by melting or by the thinning effects of the glacier stretching out. The Antarctic glaciers studied by Rignot’s group have thinned so much they are now floating above places where they used to sit solidly on land, which means their grounding lines are retreating inland.

“The grounding line is buried under a thousand or more meters of ice, so it is incredibly challenging for a human observer on the ice sheet surface to figure out exactly where the transition is,” Rignot said. “This analysis is best done using satellite techniques.”

The team used radar observations captured between 1992 and 2011 by the European Earth Remote Sensing (ERS-1 and -2) satellites to map the grounding lines’ retreat inland. The satellites use a technique called radar interferometry, which enables scientists to measure very precisely — within less than a quarter of an inch — how much Earth’s surface is moving. Glaciers move horizontally as they flow downstream, but their floating portions also rise and fall vertically with changes in the tides. Rignot and his team, which includes researchers from UC Irvine and JPL, mapped how far inland these vertical motions extend to locate the grounding lines.

The accelerating flow speeds and retreating grounding lines reinforce each other. As glaciers flow faster, they stretch out and thin, which reduces their weight and lifts them farther off the bedrock. As the grounding line retreats and more of the glacier becomes waterborne, there’s less resistance underneath, so the flow accelerates.

Slowing or stopping these changes requires pinning points — bumps or hills rising from the glacier bed that snag the ice from underneath. To locate these points, researchers produced a more accurate map of bed elevation that combines ice velocity data from ERS-1 and -2 and ice thickness data from NASA’s Operation IceBridge mission and other airborne campaigns. The results confirm no pinning points are present upstream of the present grounding lines in five of the six glaciers. Only Haynes Glacier has major bedrock obstructions upstream, but it drains a small sector and is retreating as rapidly as the other glaciers.

The bedrock topography is another key to the fate of the ice in this basin. All the glacier beds slope deeper below sea level as they extend farther inland. As the glaciers retreat, they cannot escape the reach of the ocean, and the warm water will keep melting them even more rapidly.

The accelerating flow rates, lack of pinning points and sloping bedrock all point to one conclusion, Rignot said.

“The collapse of this sector of West Antarctica appears to be unstoppable,” he said. “The fact that the retreat is happening simultaneously over a large sector suggests it was triggered by a common cause, such as an increase in the amount of ocean heat beneath the floating sections of the glaciers. At this point, the end of this sector appears to be inevitable.”

Because of the importance of this part of West Antarctica, NASA’s Operation IceBridge will continue to monitor its evolution closely during this year’s Antarctica deployment, which begins in October. IceBridge uses a specialized fleet of research aircraft and the most sophisticated suite of science instruments ever assembled to characterize changes in thickness of glaciers, ice sheets and sea ice.

For additional images and video related to this new finding, visit: http://go.nasa.gov/1m6YZSf

For additional information on the West Antarctic Ice Sheet and its potential contribution to sea level rise, visit: http://go.nasa.gov/1oIfSlO

For more information on Operation IceBridge, visit: http://www.nasa.gov/icebridge

###

The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 62,000 members in 144 countries. Join our conversation on FacebookTwitter, YouTube, and other social media channels.

The California Institute of Technology in Pasadena manages JPL for NASA.

NASA monitors Earth’s vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth’s interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet. For more information about NASA’s Earth science activities in 2014, visit: http://www.nasa.gov/earthrightnow

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this accepted article by clicking on this link: http://onlinelibrary.wiley.com/doi/10.1002/2014GL060140/abstract

Or, you may order a copy of the final paper by emailing your request to Peter Weiss at pweiss@agu.org. Please provide your name, the name of your publication, and your phone number.

Neither the paper nor this press release is under embargo.

Title

“Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011”

Authors:
E. Rignot: University of California Irvine, Dept. Earth System Science, Irvine, CA, USA; and Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA;

J. Mouginot and M. Morlighem: University of California Irvine, Dept. Earth System Science, Irvine, CA, USA;

H. Seroussi: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA;

B. Scheuchl: University of California Irvine, Dept. Earth System Science, Irvine, CA, USA.

Contact information for the authors:
Eric Rignot: +1 (818) 653-2531, Eric.J.Rignot@jpl.nasa.gov

AGU Contact:

Peter Weiss
+1 (202) 777-7507
pweiss@agu.org

NASA Headquarters Contact:
Steve Cole
+1 (202) 358-0918
stephen.e.cole@nasa.gov

NASA Jet Propulsion Laboratory Contact:
Alan Buis
+1 (818) 354-0474
alan.buis@jpl.nasa.gov

University of California Irvine Contact:
Janet Wilson
+1 (949) 824-3969
janet.wilson@uci.edu

Peter Weiss | American Geophysical Union
Further information:
http://news.agu.org/press-release/new-study-indicates-loss-of-west-antarctic-glaciers-appears-unstoppable/

Further reports about: AGU Antarctic Antarctica Geophysical IceBridge NASA Propulsion glaciers satellites

More articles from Earth Sciences:

nachricht Root exudates affect soil stability, water repellency
18.04.2018 | American Society of Agronomy

nachricht Newly discovered salty subglacial lakes could help search for life in solar system
12.04.2018 | University of Texas at Austin

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

Im Focus: The Future of Ultrafast Solid-State Physics

In an article that appears in the journal “Review of Modern Physics”, researchers at the Laboratory for Attosecond Physics (LAP) assess the current state of the field of ultrafast physics and consider its implications for future technologies.

Physicists can now control light in both time and space with hitherto unimagined precision. This is particularly true for the ability to generate ultrashort...

Im Focus: Stronger evidence for a weaker Atlantic overturning

The Atlantic overturning – one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards – is weaker today than any time before in more than 1000 years. Sea surface temperature data analysis provides new evidence that this major ocean circulation has slowed down by roughly 15 percent since the middle of the 20th century, according to a study published in the highly renowned journal Nature by an international team of scientists. Human-made climate change is a prime suspect for these worrying observations.

“We detected a specific pattern of ocean cooling south of Greenland and unusual warming off the US coast – which is highly characteristic for a slowdown of the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Improved stability of plastic light-emitting diodes

19.04.2018 | Power and Electrical Engineering

Enduring cold temperatures alters fat cell epigenetics

19.04.2018 | Life Sciences

New capabilities at NSLS-II set to advance materials science

18.04.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>