Please select your home edition
Edition
Barz Optics - Kids range

Ice-sheet retreat can halt due to long phases of climate warming

by British Antarctic Survey on 20 Oct 2012
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.


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 British Antarctic Survey website

T Clewring One DesignWildwind 2016 660x82Naiad

Related Articles

WHO statement on Zika virus
The third meeting of the EC convened by the Director-General under IHR 2005 regarding microcephaly and Zika virus The third meeting of the Emergency Committee (EC) convened by the Director-General under the International Health Regulations (2005) (IHR 2005) regarding microcephaly, other neurological disorders and Zika virus was held by teleconference on 14 June 2016, from 13:00 to 17:15 Central European Time.
Posted on 16 Jun
Atlantic Cup 2016 - a race with an environmental commitment
The Atlantic Cup continues to further its mission for the 2016 race by examining the global economic impact of the ocean The Atlantic Cup continues to further its mission for the 2016 race by examining the global economic impact of the ocean and how an unhealthy ocean can affect the economy.
Posted on 7 Apr
Zika virus situation report
From 1 January 2007 to 16 March 2016, Zika virus transmission was documented in a total of 59 countries and territories. From 1 January 2007 to 16 March 2016, Zika virus transmission was documented in a total of 59 countries and territories. Cuba and Dominica are the latest to report autochthonous (local) transmission of Zika virus on 14 and 15 March, respectively. Five of these countries and territories reported a Zika virus outbreak that is now over.
Posted on 2 Apr
Have Norway scientists solved the Bermuda Triangle mystery?
The Bermuda Triangle has been said to have claimed numerous ships and aircraft over the years The Bermuda Triangle has been said to have claimed numerous ships and aircraft over the years, and everything from aliens to remnants from the lost island of Atlantis have been fingered as the culprits.
Posted on 15 Mar
Cyclone Winston Relief Fund – Help the people of Fiji
Sea Mercy is sending volunteer fleet of small and large vessels, loaded with shelter, food and medical supplies to Fiji. Sea Mercy is once again sending our volunteer fleet of small and large vessels, loaded with shelter, food, water and medical supplies and teams to Fiji.
Posted on 27 Feb
Flying Scot Atlantic Coast Champs - Hanson Medals awarded for rescues
US Sailing Safety at Sea Committee awarded the Arthur B. Hanson Rescue Medals to eight boats for their heroic efforts The US Sailing Safety at Sea Committee awarded the Arthur B. Hanson Rescue Medals to eight boats for their heroic efforts when a microburst storm hit the 2015 Flying Scot Atlantic Coast Championship, hosted by the Blackbeard Sailing Club, in New Bern, NC on September 12.
Posted on 2 Feb
Eco-warriors Sea-Bin crowd sharing critical stage with nine days to go
The automated marina cleaning SeaBin project has raised 86% of their target with 9 days left. The automated marina cleaning SeaBin project has raised $198,020 of $230,000.00 with nine days left on their Indiegogo crowdfunding platform, but they need more help now.
Posted on 29 Dec 2015
Higher levels of Fukushima Cesium detected offshore
Scientists monitoring the spread of radiation in the ocean from the Fukushima nuclear accident report Scientists monitoring the spread of radiation in the ocean from the Fukushima nuclear accident report finding an increased number of sites off the US West Coast showing signs of contamination from Fukushima. This includes the highest detected level to date from a sample collected about 1,600 miles west of San Francisco.
Posted on 6 Dec 2015
Don’t be a Tosser – Not your usual environmental article!!
The word ‘Tosser’ in the Oxford English dictionary means – ‘a person or thing that throws something’. The word ‘Tosser’ in the Oxford English dictionary means – ‘a person or thing that throws something’. There is no need for me to tell you the other meaning that is commonly used around the world. However in this article it will refer to both at the same time as someone who tosses trash into the ocean, truly is a tosser.
Posted on 3 Dec 2015
Warming ocean worsened Australia’s fatal 2010/2011 floods
Researchers shows that warming of Indian and Pacific oceans played a role in increasing the risk of floods in 2010/2011 A study by a team of U.S. and Australian researchers shows that long-term warming of the Indian and Pacific oceans played an important role in increasing the risk of the kind of devastating floods that struck Australia in 2010/2011.
Posted on 21 Nov 2015