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

































































Rolex Big Boat Series - Plenty maintains lead by Tink Chambers, San Francisco


2014 Asia Pacific Student Cup - Count down begins
Extreme Sailing Series: Live coverage of Day 3 - view here
Volvo Ocean Race 2014-15 - Going away
Volvo Ocean Race 2014-15 - Practice makes perfect
2014 J/70 World Championship - Contrasting conditions on Day 4
Rolex Big Boat Series - 50 years of big boat racing: a retrospective
2014 Rolex Big Boat Series - Day 2
Snipe Western Hemisphere and Orient Champ: Rios takes the Championship
Volvo Ocean Race: Leg Zero signals start of the significant racing
Extreme Sailing Series: Physically demanding racing for BAR on Day 2
Emirates Team NZ: Holding second overall after Day 2 in Istanbul
Extreme Sailing Series: A force to be reckoned with in Istanbul +Video
ISAF Sailing Worlds - Day 1 images by Jesus Renedo and Pedro Martinez
Marseille One Design: GC32's Armin Strom storms ahead on day 2 + Video
ISAF Sailing World Championships - Racing underway in Santander +Video
ISAF Sailing Worlds, Santander - Erika Reineke claims Radial race win
Santander Worlds 2014 Mat Belcher (Part II) *Feature
Rolex Swan Cup - Mistral keeps fleet shoreside
PWA Cold Hawaii World Cup rescued by wave of local support
ISAF Sailing World Championship, Santander - Opening ceremony images
Volvo Ocean Race 2014-15 - Team Alvimedica geared up for Leg Zero   
J/70 World Championship 2014 - Healy surfs into lead   
2014 Rolex Big Boat Series - Day 1   
2014 Rolex Big Boat Series - Gripping first day on the Bay   
2014 Rolex Big Boat Series - Day 1 images by Erik Simonson   
2014 Snipe Western Hemisphere and Orient Championship - Day 4   
Rolex Big Boat Series - Familiar conditions on day 1   
Extreme Sailing Series: Team NZ share lead after Day 1 in Istanbul   
ISAF Sailing World Championships - Thousands attend Santander opening   
Rolex Swan Cup - Day 2 images by Carlo Borlenghi   
GC32: Great Cup: Day 1, Foils, flying and an unstoppable Flavio   
Rolex Swan Cup - Classic day of racing on the Costa Smeralda   
Extreme Sailing Series - Pushed to the limit and dismasted on Day 1   
Volvo Ocean Race - A profile of Abu Dhabi Ocean Racing   
J/70 World Championship - Day 2 images by Chris Howell   
Volvo Ocean Race 2014-15 - Lego Zero crisis scenarios loom   
America's Cup: Bob Fisher on the state of the Cup   
Interview with West Coast International Canoe pioneer Del Olsen: Video   
2015 RC44 Championship Tour announced   
Extreme Sailing Series: Precious practice time put to good use   


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