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



































































Sailing through STEM Night at California YC
Six Metre European Championship - High temps and little wind on day 3
Women’s Match Race Golfe du Morbihan - Light wind opener in Vannes
International Moth Worlds: Rashley ahead as Aussies close in
ISAF Youth Match Racing Worlds - American unbeatable on day 1
RS Feva World Championships - All set at Yacht Club de Carnac
ISAF Rolex World Sailor of the Year Awards - Nominations now open
BIC Techno 293 Worlds - Steady winds on day 2 + Video
29er North American Open Championship - Qualifying series wraps up
Opening ceremony O'pen Bic World Cup, Travemunde Week, Germany
Six Metre Europeans - Wind fails to make an appearance on day 2
Edgartown Race Weekend - Let the sailing (and good times) begin
ISAF Youth Match Racing World Championship - Action commences July 23
International Moth Worlds - Mothballed on day 4 + Video
Spirits high as Team Alvimedica completes Transatlantic crossing
Gladwell's Line: A change of direction needed in the America's Cup *Feature
29er North American Championship - Day 1 in Kingston
Red Bull 49erFX: First look at the Olympic sailing venue at Rio
Fuerteventura Kiteboarding Grand Slam - Classic conditions on day 3
NYYC Race Week Part II images by Rolex/Daniel Forster
Drowning or electric shock? What you need to know to help save a life   
BIC Techno 293 Worlds 2014 - Day 1   
Six Metre European Championship - Blazing sunshine on opening day   
National Sailing Hall of Fame to present Lifetime Achievement Award   
International Moth Worlds: Greenhalgh and Rashley tied at the top   
PWA Pozo World Cup - Fantastic finale determines winners   
Six Metre Class British Open Championship - Llanoria and Valhalla win   
Anna Tunnicliffe set to compete at the CrossFit Games   
America's Cup: Oracle Team USA holds foiling camp at Wangi SC   
Volvo Ocean Race: Abu Dhabi OR completes double Atlantic crossing   
Volvo Ocean Race: Team SCA has a 'pull through day' off the Canaries   
No tiller sailing - how to steer using just the sails + Video   
International Moth Worlds: Three bullets in a row for Greenhalgh   
U.S. Junior Women’s Singlehanded Championship - Sophia Reineke wins   
BIC Techno 293 Worlds 2014 - Day 0 Opening   
Fuerteventura World Cup - Slalom action highlights day 2   
2014 Governor's Cup - Sam Gilmour of RFBYC victorious again   
Farr 40 West Coast Champ - Skipper Alberto Rossi leads Enfant Terrible   
Flying Dutchman World Championships - Magyars are the Masters   
Final day shakes up standings at Cape Panwa Hotel Phuket Raceweek   


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