Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

West Antarctic Ice Shelves Tearing Apart at the Seams

28.03.2012
A new study examining nearly 40 years of satellite imagery has revealed that the floating ice shelves of a critical portion of West Antarctica are steadily losing their grip on adjacent bay walls, potentially amplifying an already accelerating loss of ice to the sea.

The most extensive record yet of the evolution of the floating ice shelves in the eastern Amundsen Sea Embayment in West Antarctica shows that their margins, where they grip onto rocky bay walls or slower ice masses, are fracturing and retreating inland. As that grip continues to loosen, these already-thinning ice shelves will be even less able to hold back grounded ice upstream, according to glaciologists at The University of Texas at Austin’s Institute for Geophysics (UTIG).


Rifts along the northern shear margin of Pine Island Glacier (upper right of image). Credit: Michael Studinger, NASA's Operation IceBridge

Reporting in the Journal of Glaciology, the UTIG team found that the extent of ice shelves in the Amundsen Sea Embayment changed substantially between the beginning of the Landsat satellite record in 1972 and late 2011. These changes were especially rapid during the past decade. The affected ice shelves include the floating extensions of the rapidly thinning Thwaites and Pine Island Glaciers.

“Typically, the leading edge of an ice shelf moves forward steadily over time, retreating episodically when an iceberg calves off, but that is not what happened along the shear margins,” says Joseph MacGregor, research scientist associate and lead author of the study. An iceberg is said to calve when it breaks off and floats out to sea.

“Anyone can examine this region in Google Earth and see a snapshot of the same satellite data we used, but only through examination of the whole satellite record is it possible to distinguish long-term change from cyclical calving,” says MacGregor.

The shear margins that bound these ice shelves laterally are now heavily rifted, resembling a cracked mirror in satellite imagery until the detached icebergs finally drift out to the open sea. The calving front then retreats along these disintegrating margins. The pattern of marginal rifting and retreat is hypothesized to be a symptom, rather than a trigger, of the recent glacier acceleration in this region, but this pattern could generate additional acceleration.

“As a glacier goes afloat, becoming an ice shelf, its flow is resisted partly by the margins, which are the bay walls or the seams where two glaciers merge,” explains Ginny Catania, assistant professor at UTIG and co-author of the study. “An accelerating glacier can tear away from its margins, creating rifts that negate the margins’ resistance to ice flow and causing additional acceleration.”

Location of Amundsen Sea Embayment

The UTIG team found that the largest relative glacier accelerations occurred within and upstream of the increasingly rifted margins.

The observed style of slow-but-steady disintegration along ice-shelf margins has been neglected in most computer models of this critical region of West Antarctica, partly because it involves fracture, but also because no comprehensive record of this pattern existed. The authors conclude that several rifts present in the ice shelves suggest that they are poised to shrink further.

This research is sponsored in part by the National Science Foundation.

The article, titled “Widespread rifting and retreat of ice-shelf margins in the eastern Amundsen Sea Embayment between 1972 and 2011”, appears in issue #209 of Journal of Glaciology.

Marc Airhart | EurekAlert!
Further information:
http://www.utexas.edu
http://www.jsg.utexas.edu/news/?p=3471

More articles from Earth Sciences:

nachricht Tundra study uncovers impact of climate warming in the Arctic
07.07.2015 | University of Edinburgh

nachricht NASA's infrared look at strengthening Typhoon Chan-Hom
07.07.2015 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Surfing a wake of light

Researchers observe and control light wakes for the first time

When a duck paddles across a pond or a supersonic plane flies through the sky, it leaves a wake in its path. Wakes occur whenever something is traveling...

Im Focus: Light-induced Magnetic Waves in Materials Engineered at the Atomic Scale

Researchers explore ultrafast control of magnetism across interfaces: A new study discovers how the sudden excitation of lattice vibrations in a crystal can trigger a change of the magnetic properties of an atomically-thin layer that lies on its surface.

A research team, led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter at CFEL in Hamburg, the University of Oxford, and the...

Im Focus: Viaducts with wind turbines, the new renewable energy source

Wind turbines could be installed under some of the biggest bridges on the road network to produce electricity. So it is confirmed by calculations carried out by a European researchers team, that have taken a viaduct in the Canary Islands as a reference. This concept could be applied in heavily built-up territories or natural areas with new constructions limitations.

The Juncal Viaduct, in Gran Canaria, has served as a reference for Spanish and British researchers to verify that the wind blowing between the pillars on this...

Im Focus: X-rays and electrons join forces to map catalytic reactions in real-time

New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions

A new technique pioneered at the U.S. Department of Energy's Brookhaven National Laboratory reveals atomic-scale changes during catalytic reactions in real...

Im Focus: Iron: A biological element?

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.

Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Conference on Regenerative Medicine in Leipzig: Last chance to submit abstracts until 2 July

25.06.2015 | Event News

World Conference on Regenerative Medicine: Abstract Submission has been extended to 24 June

16.06.2015 | Event News

MUSE hosting Europe’s largest science communication conference

11.06.2015 | Event News

 
Latest News

Down to the quantum dot

07.07.2015 | Physics and Astronomy

Tundra study uncovers impact of climate warming in the Arctic

07.07.2015 | Earth Sciences

Transition from 3 to 2 dimensions increases conduction, MIPT scientists discover

07.07.2015 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>