Observatoire الملحظ
Derniers articles آخر ما نشر
Page d'accueil الاستقبال
KHEREDDINE 2015-2016 أين المبادئ
Signaler l'abus: plainte ou information
www.ho-net.net presentation
2011-2012تونس:مسائل راهنة
Profils de detresse humaine
Vie et société plus saines حياة أفضل و مجتمع أحسن
Opinions آراء
Tunisie: bien etre ou savoir faire?
Tunisie : confiants, ou credules ?
Cafeteria Culturelle منتزه ثقافي
Parole à l'image (1)
Gestion des Catastrophes التصرف في الكوارث
Offres d'assistance ou demandes d'aide
Declaration universelle: Les Textes des droits de l'homme:
Micro-mensonges et tyrannismes pour macro nuisances!
Comment promouvoir les droits de l'homme?
Changements climatiques
=> Gestion et debut des études du changement climatique
=> Album
=> La Terre en chiffres
=> Actualites de 2008
=> Fonte de la glace éternelle
=> Retour a la fonte des glaciers :Ice shelves melting
=> Effet de serre: mieux comprendre le phénomène
=> Augmentation de la température de la terre
=> Lien entre réchauffement et catastrophes
Rapports a propos du net et la condition humaine (dh)
Articles jadis masques depuis l'été 12
Environnement et civilisation
Guide Urgences Santé
Vulgarisation du web
Mon internet
Annonces tous azimuts!
Impacts sociaux du web
Histoire de l'internet
Actualites internet et computering
Le sens des mots : Glossaire
Le tour du monde
Histoires dans la vie
Soutenez Chatt eljerid: merveilles du monde
Abonnement des mises à jour,Newsletter
Livre d'or
Search site
Qui suis je
Titre de la nouvelle page
الشيخ و الطفل في الطريق : الرفق لا يتعلم

Retour a la fonte des glaciers :Ice shelves melting

Home      Changements climatiques      Ice shelves melting
 Retour a la fonte des glaciers :Ice shelves melting

On pense que les méfaits du changement climatique sont loin de notre génération. GRAVE ERREUR! Lisez cette étude anglosaxonne.



Ancient ice shelf breaks free in Canadian Arctic


Breakaway may 'signal the onset of accelerated change,'
researchers say

This NASA satellite image shows the Ayles Ice Shelf collapse, center and below the open water, on Aug. 13, 2005. Within days of breaking free and becoming an island, Ayles drifted about 30 miles before freezing into the sea ice seen here along top of photo.

Video: Environment  

Dec. 22: T. Boone Pickens, the founder of BP Capital Management, joins the Morning Joe gang to discuss the United States' march towards engery independence.

Environment slide shows  
Image: Yellowstone National Park
Yann Arthus-Bertrand

From a mangrove swamp with a natural heart, to a tree of life in a desert savanna, check out the planet from a bird's-eye view.

  Photo features  

Experience an audio slide show of the best news and sports images from around the world and close to home.
Image: Protesters in the National Assembly in Seoul, South Korea
Yonhap via AP

View and discuss the pictures and issues that caught our eyes.

msnbc.com news services
updated 7:40 p.m. ET Dec. 29, 2006



TORONTO - A giant ice shelf has snapped free from an island
south of the North Pole, scientists said Thursday, citing
change as a “major” reason for the event.



The Ayles Ice Shelf — about the size of Manhattan — broke
16 months ago from the coast of Ellesmere Island, about 500
south of the North Pole in the Canadian Arctic.



Scientists discovered the event by using satellite imagery.
one hour of breaking free, the shelf had formed as a new ice
leaving a trail of icy boulders floating in its wake.





Warwick Vincent of Laval University, who studies Arctic
conditions, traveled to the newly formed ice island and
couldn’t believe what he saw.



“This is a dramatic and disturbing event. It shows that we
are losing remarkable features of the Canadian North that
have been in place for many thousands of years,” Vincent
“We are crossing climate thresholds, and these may signal
the onset of accelerated change ahead.”



The ice shelf was one of six major shelves remaining in
Canada’s Arctic. They are packed with ancient ice that is
more than 3,000 years old. They float on the sea but are
connected to land.



'Consistent with climate change'
Some scientists say it is the largest event of its kind in
Canada in nearly 30 years and that climate change was a
major element.



“It is consistent with climate change,” Vincent said, adding
that the remaining ice shelves are 90 percent smaller than
when they were first discovered in 1906. “We aren’t able to
connect all of the dots ... but unusually warm temperatures
definitely played a major role.”


Laurie Weir, who monitors ice conditions for the Canadian Ice Service, was poring over satellite images in 2005 when she noticed that the shelf had split and separated.



Weir notified Luke Copland, head of the new global ice lab at the University of Ottawa, who initiated an effort to find out what happened.



Using U.S. and Canadian satellite images, as well as seismic data — the event registered on earthquake monitors 155 miles away — Copland discovered that the ice shelf collapsed in the early afternoon of Aug. 13, 2005.



Copland said the speed with which climate change has
affected the ice shelves
has surprised scientists.



“Even 10 years ago scientists assumed that when global
warming changes occur that it would happen
gradually so that perhaps we expected these ice shelves
just to melt away quite slowly,” he said.



Instead, satellite images showed the 9-mile long crack,
then the ice floating about a half mile from the coast within
about an hour, Copland said.



“You could stand at one edge and not see the other side,
and for something that large to move that quickly is quite
amazing,” he said.



Copland said the break was likely due to a combination of
low accumulations of sea ice around the mass’s edges as
high winds blew it away, as well as one of the Arctic's
warmest  temperatures on record. The region was 5.4
F above average in the summer of 2005, he said.



Ice shelves in Canada’s far north have decreased in size
by as much as 90 percent since 1906, and global warming
likely played a role in the Ayles break, Copland said.



“It’s hard to tie one event to climate change, but when you
look at the longer-term trend, the bigger picture, we’ve lost
a lot of ice shelves on northern Ellesmere in the past
century and this is that continuing,” he said. “And this is
the biggest one in the last 25 years.” 



Shipping hazard possible
Derek Mueller, a polar researcher with Vincent’s team,
said the ice shelves get weaker and weaker as temperatures
rise. He visited Ellesmere Island in 2002 and noticed that
another ice shelf had cracked in half.

Warwick Vincent / Laval University file
Part of what was the Ayles Ice Shelf is surveyed last summer by Denis Sarrazin, a researcher with the Center for Northern Studies at Laval University in Quebec City, Canada. Sarrazin and other researchers visited what is now an island as part of an expedition within a program called ArcticNet.

“We’re losing
our ice shelves
and this a
feature of the
landscape that
is in danger of
altogether from
Canada,” Mueller



Within days of breaking free, the Ayles Ice Shelf
drifted about 30 miles offshore before freezing into
the sea ice. A spring thaw may bring another concern:
that warm temperatures will release the new ice
island from its Arctic grip, making it an enormous
hazard for ships.



“Over the next few years this ice island could drift
into populated shipping routes,” Weir said.


Aujourd'hui sont déjà 15 visiteurs (55 hits) Ici!
=> Veux-tu aussi créer une site gratuit ? Alors clique ici ! <=