sail-world.com
 
 
News Home Cruising Photo Gallery Video Gallery
Sail-World.com : Ice-sheet retreat can halt due to long phases of climate warming
Ice-sheet retreat can halt due to long phases of climate warming

'Edge of the Brunt Ice Shelf, Weddell Sea'    Pete Bucktrout

Ice-sheet retreat can halt temporarily during long phases of climate warming, according to scientists. A UK team led by Durham University has found that the geometry of channels underneath the ice can be a strong control on ice behaviour, temporarily masking the signals of retreat.

The findings, which provide the first simulation of past ice-sheet retreat and collapse over a ten thousand year period in Antarctica, shed new light on what makes ice stable or unstable and will help refine predictions of future ice extent and global sea-level rise, the researchers say.

The International Panel on Climate Change (IPCC) has stated that one of the main challenges in predicting future sea-level rise is to quantify and model the interactions between evolving ice sheets, oceans, sea level and climate. Significant efforts have been made over the last decade to develop computer models and collect data in order to reduce uncertainties and understand the potential impacts under scenarios of future climate change.

The results of the new research from Durham University, the University of Sheffield, the University of Cambridge, and British Antarctic Survey are published this week in the journal Nature Geoscience.

Lead author, Dr. Stewart Jamieson, a glaciologist at the Department of Geography, Durham University, said: 'Our research shows that the physical shape of the channels is a more important factor in controlling ice stability than was previously realised. Channel width can have a major effect on ice flow, and determines how fast retreat, and therefore sea-level rise, can happen.'

Although climatic and oceanic changes are crucial drivers of ice loss, the research shows that the landscape below the ice strongly controls the speed of any retreat.

Dr. Jamieson added: 'Our results suggest that during an overall phase of retreat an ice stream can appear almost stable when in fact, in the longer-term, the opposite may be the case.

'Getting a clearer picture of the landscape beneath the ice is crucial if future predictions of change in the ice-sheets and sea level are to be improved.'

Marine-based ice streams are the fast flowing arteries of ice sheets, draining approximately 90 per cent of the ice that reaches the sea. They flow through large channels where the ice can move thousands of metres in a year. According to the scientists, the unpredictable nature of ice streams makes forecasting ice-sheet retreat extremely difficult. If ice streams speed up they can cause sea level to rise.

View of Sheldon Glacier with Mount Barre in the background, seen from Ryder Bay near Rothera Research Station, Adelaide Island, Antarctica. -  Pete Bucktrout  

Durham University co-author Dr. Chris Stokes said: 'Ice streams are like taps filling a bath, but the problem here is that we do not know if something is suddenly going to turn them up or even turn them off.'

Satellite imagery from the last 20 years has led to advances in our knowledge of ice sheet stability and has shown that many ice streams are getting thinner and retreating because the ocean and climate are warming. The new research shows that ice behaviour can successfully be simulated in places where ice streams meet the sea.

The researchers looked at the landscape of the seafloor in Marguerite Bay, in the Antarctic Peninsula, and saw that during a rapid phase of recession 13,000 years ago, retreat paused many times. Using a computer model designed to work in situations of rapid change, they found they could reproduce the same pattern in a series of simulations. These showed that ice dragged on the sides of the channel more where it was narrow, causing retreat to slow and in places temporarily stop for decades to centuries before retreat continued.

Many ice streams are found in channels with beds that are below sea level and that deepen inland. Current theory suggests that ice loss can increase rapidly in deeper water, but the new findings show that channel width plays a crucial role and that narrow bottlenecks in the landscape beneath the ice can cause retreat to slow down.

Dr. Andreas Vieli, Department of Geography, Durham University, said: 'We can see from our simulations and from new maps of the ocean floor that these bottlenecks occur in the same place as pauses or slowdowns in past ice retreat. This means we should look more closely at the shape of the bed underneath Greenland and Antarctica to better understand how ice might retreat in the future.'

Dr. Claus-Dieter Hillenbrand from British Antarctic Survey added: 'Knowledge of the factors influencing stability and retreat of ice streams is of particular concern because significant portions of the West Antarctic and Greenland ice sheets are currently losing mass that contributes significantly to sea-level rise. Our model results help to explain the apparently time-transgressive retreat of ice streams around Antarctica following the last ice age.'

The researchers say that understanding ice-stream behaviour and the rate of mass loss from ice sheets and glaciers is essential.

British Antarctic Survey website


by British Antarctic Survey

  

Click on the FB Like link to post this story to your FB wall

http://www.sail-world.com/index.cfm?nid=103023

5:59 PM Fri 19 Oct 2012GMT


Click here for printer friendly version
Click here to send us feedback or comments about this story.







News - USA and the World











America's Cup: Five Challengers sign-on for 35th Match by Richard Gladwell/Sail-World.com/nz,


Volvo Ocean Race CEO Knut Frostad talks Time and Money (Part II) *Feature by Rob Kothe and the Sail-World team,


















AWT Quatro Desert Showdown at Punta San Carlos by American Windsurfing Tour,
















America's Cup: Rod Davis - Time for a change after ten years with team *Feature by Richard Gladwell/Sail-World.com/nz,








Maxi yacht rendezvous this September in Sardinia by International Maxi Association,












Challenging Conditions - CORK OCR
IFDS World Championship - Day 1 for the US Sailing Team
2014 Melges 20 World Championship - Countdown begins
2014 Nanjing Youth Olympic Games - Day 3
America's Cup: Team NZ wish Davis well with new team *Feature
Fisher's View: Sailing perfection at Hamilton Island- Day 3
Roble and Wilson still number one match racers in the U.S.
2014 Formula Kite World Championship Day 1
IFDS World Championship - Day 1 images by Jude Robertson
Volvo Ocean Race: Forget the f-word - Team SCA profiled
52 Super Series - Fleet grows, 2015 dates revealed
420 and 470 Junior Europeans - Teams from 9 nations on the podium
IFDS Worlds - Former president presented with ISAF awards medal
Nanjing Youth Olympic Games - Improvements aplenty in Byte CII fleets
America's Cup: New Zealand loses top coach to Artemis Racing
Volvo Ocean Race 2014-15 CEO Knut Frostad talks (Part I) *Feature
Sevenstar Round Britain and Ireland Race Day 9 - Swish on record pace
2014 CORK Olympic Classes Regatta - Day 3
2014 Nanjing Youth Olympic Games - Day 2
2014 IFDS World Championship: Opening Ceremony images
Opera House Cup - Images by Ingrid Abery   
Teams descend upon Cowes for inaugural J/111 World Championships   
Hamilton Island Race Week: Everywhere there's smiley people   
IFDS World Championships - US Paralympic hopefuls ready for racing   
Sopot Match Race - Poland's Tour debut deemed a triumph   
Vineyard Race celebrates 80th running of the East Coast classic   
Nanjing Youth Olympic Games: Young sailors begin racing on Lake Jinniu   
AWT Quatro Desert Showdown - Victory for Morgan Noireaux   
Sevenstar Round Britain and Ireland Race - Day 8: Test of endurance   
Bart's Bash: Over 2300 entered from 588 yacht clubs - Join here   
Halifax ready to welcome the world at 2014 IFDS World Championships   
RC44 World Championship title to Bronenosec + Video   
Audi Hamilton Island Race Week: Day 2 Images by Crosbie Lorimer   
IFDS Worlds - Gary Jobson to attend opening ceremonies   
Melges 32 U.S. National Championship - Dalton DeVos crowned champion   
2014 Nanjing Youth Olympic Games trailer   
2014 Chicago Grand Slam - Canfield wins   
Round Britain and Ireland Race - Varuna takes overall lead   
Audi Hamilton Island Race Week; Crosbie Lorimer Day 1 Images   
Fisher's View: Hamilton Island Race Week - Day 1 - Stayin' Alive   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News







Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png http://www.sail-world.com/event_images/image/FaceBook-icon.png  http://www.sail-world.com/event_images/image/RSS-Icon.png

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph contact the photographer directly.
XLXL NEW US
LocalAds   DE  ES  FR  IT