British scientists find out why ice in the Antarctic is increasing - and say it's all down to wind
- The study shows for the first time how winds in the Antarctic cause the change in sea ice cover
- Researchers tracked changes over 19 years and analysed over 5 million measurements
By Mark Prigg
While fears continue over the melting Arctic ice caps climate change has actually increased the sea ice cover in the Antarctic, according to the first direct evidence from the region.
Scientists from Natural Environment Research Council and NASA marked changes to Antarctic sea ice drift that have occurred over the last 20 years in response to changing winds.
Unlike the dramatic losses reported in the Arctic at the opposite pole in the Antarctic sea ice cover has increased, according to maps created in NASA's Jet Propulsion Laboratory using over 5 million individual daily ice motion measurements captured over a period of 19 years by four US Defense Meteorological satellites.
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The British Antarctic Survey and Nasa believe wind in behind the rise in ice levels in the Antarctic
The new maps show wind direction (top) and correlation between winds and ice motion (bottom)
These maps show, for the first time, the long-term changes in sea ice drift around Antarctica and reveal the complexities of climate change.
The study, published in Nature Geoscience, shows for the first time how winds in the Antarctic cause the change in sea ice cover.
Lead author, Dr Paul Holland of NERC's British Antarctic Survey, said: 'Until now these changes in ice drift were only speculated upon, using computer models of Antarctic winds.
'This study of direct satellite observations shows the complexity of climate change.
'The total Antarctic sea-ice cover is increasing slowly, but individual regions are actually experiencing much larger gains and losses that are almost offsetting each other overall.
'We now know that these regional changes are caused by changes in the winds, which in turn affect the ice cover through changes in both ice drift and air temperature.
'The changes in ice drift also suggest large changes in the ocean surrounding Antarctica, which is very sensitive to the cold and salty water produced by sea-ice growth.
'Sea ice is constantly on the move;
around Antarctica the ice is blown away from the continent by strong
northward winds. Since 1992 this ice drift has changed.
'In some areas the export of ice away from Antarctica has doubled, while in others it has decreased significantly.'
Sea ice plays a key role in the global environment - reflecting heat from the sun and providing a habitat for marine life.
September 26, 2012, when ice covered more of the Southern Ocean than at any other time in the satellite record.
Increase: At the end of the southern winter in September, ice covered 7.51million square miles of sea ¿ more than at any time since records began in 1979. This image shows an icebreaker in the sea
At both poles sea ice cover is at its minimum during late summer.
However, during the winter freeze in Antarctica this ice cover expands to an area roughly twice the size of Europe. Ranging in thickness from less than a metre to several metres, the ice insulates the warm ocean from the frigid atmosphere above.
new research also helps explain why observed changes in the amount of
sea-ice cover are so different in the two Polar Regions.
The Arctic has experienced dramatic ice losses in recent decades while the overall ice extent in the Antarctic has increased slightly.
While Actic ice levels (above) are at record levels, Antarctic levels are rising due to wind, researchers said today
However, this small Antarctic increase is actually the result of much larger regional increases and decreases, which are now shown to be caused by wind-driven changes.
In places, increased northward winds have caused the sea-ice cover to expand outwards from Antarctica. The Arctic Ocean is surrounded by land, so changed winds cannot cause Arctic ice to expand in the same way.
NASA's Dr Ron Kwok said: 'The Antarctic sea ice cover interacts with the global climate system very differently than that of the Arctic, and these results highlight the sensitivity of the Antarctic ice coverage to changes in the strength of the winds around the continent.'
There has been contrasting climate change observed across the Antarctic in recent decades.
The Antarctic Peninsula has warmed as much as anywhere in the Southern Hemisphere, while East Antarctica has shown little change or even a small cooling around the coast.
The new research improves understanding of present and future climate change. It is important to distinguish between the Antarctic Ice Sheet - glacial ice - which is losing volume, and Antarctic sea ice - frozen seawater - which is expanding, the researchers claim.
LIFE IN THE ANTARCTIC
Researcher Ted Maksym is on the R.V. Aurora Australis (right) in the Antarctic conducting studies of the ice.
He is with the Woods Hole Oceanographic Institution in Massachusetts.
At well past midnight in Antarctica, where it's about 3 degrees
Fahrenheit (minus 16 Celsius), Maksym describes in a rare ship-to-shore
telephone call from the what this extra ice means in terms of climate
And what it's like to be out studying it for two months, with the nearest city 1,500 miles (2,415 kilometers) away.
'It's only you and the penguins,' he says. 'It's really a strikingly beautiful and stark landscape.
'Sometimes it's even an eerie kind of landscape.'
Scientists on the cruise with Maksym are spending eight to 12 hours a day on the ice.
Cracks in sea ice can form at
any time, and a few days ago a sudden fissure stranded a team of
scientists until an inflatable bridge rescued them.
'It's a treacherous landscape,' Vaughan says.