Please select your home edition
Edition
Predictwind - Iridium

New Antarctic seabed sonar images reveal clues to sea-level rise

by British Antarctic Survey media on 12 May 2009
British Antarctic Survey © http://www.antarctica.ac.uk
Motorway-sized troughs and channels carved into Antarctica’s continental shelves by glaciers thousands of years ago could help scientists to predict future sea-level rise according to a report in the journal Geology this month (May).

Using sonar technology from onboard ships, scientists from British Antarctic Survey (BAS) and the German Alfred Wegener Institute (AWI) captured the most extensive, continuous set of images of the seafloor around the Amundsen Sea embayment ever taken. This region is a major drain point of the West Antarctic Ice Sheet (WAIS) and considered by some scientists to be the most likely site for the initiation of major ice sheet collapse.



The sonar images reveal an ‘imprint’ of the Antarctic ice sheet as it was at the end of the last ice age around 10 thousand years ago. The extent of ice covering the continent was much larger than it is today. The seabed troughs and channels that are now exposed provide new clues about the speed and flow of the ice sheet. They indicate that the controlling mechanisms that move ice towards the coast and into the sea are more complex than previously thought.

Lead author Rob Larter from British Antarctic Survey said, 'One of the greatest uncertainties for predicting future sea-level rise is Antarctica’s likely contribution. It is very important for scientists and our society to understand fully how polar ice flows into the sea. Indeed, this issue was highlighted in 2007 by the Intergovernmental Panel on Climate Change (IPCC). Our research tells us more about how the ice sheet responded to warming at the end of the last ice age, and how processes at the ice sheet bed controlled its flow. This is a big step toward understanding of how the ice sheets are likely to respond to future warming.’
[Sorry, this content could not be displayed]
Background

For the past 20 years scientists studying the Greenland and Antarctic ice sheets have used a range of technologies, including satellite images, ice-penetrating radar and other techniques to monitor the movement of ice as it flows from Antarctica’s interior towards the coast.

Science teams often work in remote and extreme locations to measure change in their attempts to understand their likely contribution to global sea-level rise.

This work is the result of a collaboration between scientists onboard two research cruises in 2006 – Jan-Feb BAS ship RRS James Clark Ross; Feb-Mar onboard AWI ship RV Polarstern. Ship-borne research cruises provide crucial information about Antarctica’s ice sheet and climate history. This data combined with that from other satellite and ground-based studies help provide answers to big environmental questions that are relevant to people all over the world.

The area of the Amundsen Sea embayment surveyed was 9950 km2. This is equal to -
- Nearly half the size of Wales (20,799 sq.km)
- Nearly the size of Yorkshire (11,903 sq.km, since 1991)
- Larger than Norfolk and Suffolk combined (9172 sq.km)

In the western Amundsen Sea embayment three 17-39 km wide troughs extend seaward from the modern ice shelf front. This is roughly with width of the English Channel. Individual streamlined features carved into the seabed are about as wide as a motorway.

Ice sheet
The Antarctic ice sheet retreated to near its present limit around 10 thousand years ago. It is the layer of ice up to 5000 m thick covering the Antarctic continent. It is formed from snow falling in the interior of the Antarctic which compacts into ice. The ice sheet slowly moves towards the coast, eventually breaking away as icebergs which gradually melt into the sea.

The ice sheet covering East Antarctica is very stable, because it lies on rock that is above sea level and is thought unlikely to collapse. The West Antarctic is less stable, because it sits on rock below sea level.

Ice shelf
An ice shelf is a thick (100-1000 m), floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface. Ice shelves are found in Antarctica, Greenland and Canada only.

Glacier
Just as rivers collect water and allow it to flow downhill a glacier is actually a 'river' of ice. A glacier flows much more slowly than river. Rivers of ice within ice sheets account for most of the drainage into the oceans.

Continental shelf
The relatively shallow (generally up to 200 meters) seabed surrounding a continent where the depth gradually increases before it plunges into the deep ocean. Around Antarctica the continental shelf is up to 1600 m deep as a result of millions of years of glacial erosion. The deepest parts of the Antarctic continental shelf are near the present ice margin and depths generally decrease offshore.

The Cambridge-based British Antarctic Survey (BAS) is a world leader in research into global environmental issues. With an annual budget of around £45 million, five Antarctic Research Stations, two Royal Research Ships and five aircraft, BAS undertakes an interdisciplinary research programme and plays an active and influential role in Antarctic affairs. BAS has joint research projects with over 40 UK universities and has more than 120 national and international collaborations. It is a component of the Natural Environment Research Council.

More information about the work of the Survey can be found at: www.antarctica.ac.uk

Mackay BoatsAncasta Ker 40+ 660x82Wildwind 2016 660x82

Related Articles

The America's Cup Superyacht Program – A true highlight
The 35th America’s Cup in Bermuda will feature the fastest yachts in the 166 year history of the competition Superyachts are a very important part of the America’s Cup and, reflecting the high value of their role in the events that will take place in Bermuda in May and June, a dedicated America’s Cup Superyacht Program was created by the America’s Cup Event Authority (ACEA), in conjunction with BWA Yachting.
Posted on 28 Mar
America's Cup - Talbot Wilson reports from the Practice Series
Bermudan based sailing journalist, Talbot Wilson looks at the first five day practice racing session just concluded Talbot Wilson looks at the first five day practice racing session just concluded in Bermuda. All five America’s Cup teams training in Bermuda have wrapped up the first of six “practice racing periods” allowed under the latest changes to the 2017 America’s Cup protocol. The protocol changes were approved March 16 by the defender, Oracle Team USA and signed by the four challengers in Bermuda.
Posted on 28 Mar
Volvo Ocean Race - Team AkzoNobel leaves Persico
The Simeon Tienpont skippered Team AkzoNobel Volvo65 has left the building facility at Persico Marine in Bergamo The Simeon Tienpont skippered Team AkzoNobel Volvo65 has left the building facility at Persico Marine in Bergamo, Italy to The Boatyard in Lisbon under the custodianship of GAC Pindar. Before she left the yard at Persico the team had a celebration to mark the end of the build phase.
Posted on 27 Mar
America's Cup - First five day round of practice racing concludes
The latest round of America’s Cup Class (ACC) practice racing ahead of the 35th America’s Cup has concluded The latest round of America’s Cup Class (ACC) practice racing ahead of the 35th America’s Cup concluded on a beautiful spring Sunday on the Great Sound. All five America’s Cup teams now based in Bermuda took part in a series of match races in varied conditions, racing each other on a course that closely mirrors that to be used in May and June 2017
Posted on 27 Mar
America's Cup - Oracle picks up some bow protection for docking
Bangin' the Corner team talk Jimmy and the boys on Oracle Team USA through the process of getting some bow protection The Bangin' the Corner team talk Jimmy and the boys on Oracle Team USA through the process of getting some bow protection for their new AC50, before they dock after a long day on the Great Sound, and don't dock like Ben did.
Posted on 26 Mar
Bureau Vallée 2 back in the water in Brittany
The former Banque Populaire VIII aboard which Armel Le Cléac’h won the last Vendée Globe was put back in the water The former Banque Populaire VIII aboard which Armel Le Cléac’h won the last Vendée Globe was put back in the water on Friday in Lorient (Brittany), with her new decoration in the colours of Bureau Vallée.
Posted on 25 Mar
America's Cup - Bermuda practice racing videos March 24, 2017
MyislandhomeBDA is videoing the Practice racing and training with the five teams in Bermuda MyislandhomeBDA is videoing the Practice racing and training with the five teams who are based in the venue for the 2017 America's Cup. Here's the set from March 24,2017
Posted on 25 Mar
America's Cup - Coutts hits back at critics over Protocol change
Russell Coutts, has responded to criticism over the recent changes to the 35th America's Cup Protocol Five times America's Cup winner and CEO of the America's Cup Events Authority, Russell Coutts, has responded to criticism over the recent changes to the 35th America's Cup Protocol, allowing testing and racing between Challengers and the Defender in Bermuda ahead of the start of the Qualifiers.
Posted on 24 Mar
America's Cup - Groupama Team France's AC50 sailing in Bermuda - Video
Groupama Team France has had her first sail in Bermuda with the AC50 looking impressive in the video shot by the team. Groupama Team France has had her first sail in Bermuda with the AC50 looking impressive in the video shot by the team.
Posted on 24 Mar
America's Cup - Images of Emirates Team NZ flypast Devonport
Image gallery shot as Emirates Team New Zealand returned in the late afternoon from another four hour race session Image gallery shot as Emirates Team New Zealand returned in the late afternoon from another four hour race training session on the Waitemata harbour. Our cameras were on Devonport Wharf to catch the sequence - and for the first time a wide angle lens had to be used.
Posted on 23 Mar