Tuesday, May 13, 2014

Ice Loss from Antarctic Glacier Unstoppable

A large portion of the West Antarctic Ice Sheet is melting rapidly, and appears to be in an irreversible state of decline. That assessment, from a new study by researchers at NASA and the University of California, Irvine, finds that there is nothing to stop the glaciers in the area from melting into the sea.

Glaciologist and lead author Eric Rignot told a news conference Monday that the melting will be a major contributor to sea level rises in the decades and centuries to come.

"We and many other colleagues have looked extensively at this part of the world over the last two decades, with satellites, airplanes, ships and ground survey. We have examined enough direct and independent observations of this part of the world to conclude that the retreat of ice in that sector is unstoppable," said Rignot.

The glaciers in the Amundsen Sea sector of West Antarctica contain enough ice to raise the global sea level by more than a meter, and are melting faster than most scientists had expected. They already release almost as much ice into the oceans annually as the entire Greenland Ice Sheet.

The report, which appears in the journal Geophysical Research Letters, concludes: "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." 

  • The researchers say while cutting CO2 emissions could slow the glacier loss, they stress it could not reverse it.

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



  1. Antarctique : on sait maintenant que la fonte des glaces est bien irréversible...

    Deux études montrent que la fonte des glaciers de l'ouest du continent austral va provoquer une montée du niveau des mers de 4 mètres dans les prochains siècles.

    La fonte des glaces de la partie ouest de l'Antarctique est irréversible : telle est la conclusion d'une étude menée par des chercheurs de la Nasa et de l'université d'Irvine (Californie) et qu'ils viennent de publier dans la revue Geophysical Research Letters.

    Même conclusion pour l'étude menée par des chercheurs de l'université de Washington, pour qui cette fonte pourrait s'étaler sur une échelle de temps allant de 200 ans à 1.000 ans pour l'hypothèse la plus optimiste.
    Autant d'eau dans l'océan que le Groenland entier

    Se basant sur 40 ans d'observation des glaciers dans la région de la mer d'Amundsen, dans l'ouest de l'Antarctique, les chercheurs californiens déduisent que ceux-ci ont dépassé le point de non retour. Il ne s'agit pas là de modélisations informatiques, mais bien de l'interprétation d'observations effectuées sur place, insiste le principal auteur de l'étude, Eric Rignot, glaciologue au Jet Propulsion Laboratory (Nasa) et professeur à l'université d'Irvine.

    "Ces glaciers contribuent déjà de manière significative à la montée du niveau des mers, la fonte de leurs glaces produisant pratiquement autant d'eau dans les océans que le Groenland entier", expliquent les scientifiques. Et "ils contiennent assez de glace pour faire augmenter le niveau des mers de 1,2 mètres. Mais ce n'est pas tout : le professeur Rignot indique que ces prévisions peuvent être largement augmentée par l'influence qu'ont les glaciers étudiés sur trois autres bassins, ce qui porterait la fourchette de montée globale des eaux à entre 3 et 4,5 mètres......................empsreel.nouvelobs.com/sciences/20140512.OBS6867

  2. West Antarctic Ice Sheet collapse is under way...

    University of Washington researchers used detailed topography maps and computer modeling to show that the collapse appears to have already begun. The fast-moving Thwaites Glacier will likely disappear in a matter of centuries, researchers say, raising sea level by nearly 2 feet. That glacier also acts as a linchpin on the rest of the ice sheet, which contains enough ice to cause another 10 to 13 feet (3 to 4 meters) of global sea level rise. The study will be published on May 16 in Science.

    "There's been a lot of speculation about the stability of marine ice sheets, and many scientists suspected that this kind of behavior is under way," said Ian Joughin, a glaciologist at the UW's Applied Physics Laboratory. "This study provides a more quantitative idea of the rates at which the collapse could take place."

    The good news is that while the word "collapse" implies a sudden change, the fastest scenario is 200 years, and the longest is more than 1,000 years. The bad news is that such a collapse may be inevitable...................Read more at: http://phys.org/news/2014-05-west-antarctic-ice-sheet-collapse.html#jCp


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