Mystery over holes the size of SWITZERLAND appearing in Antarctic ice finally solved - The Sun

HUGE holes in Antarctic sea ice have been appearing for weeks at a time – and scientists may finally know why.

The gaps, which can each cover an area the size of Switzerland, are caused by wicked weather conditions and underwater vortexes, according to a new study.

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Hole in sea ice offshore of the Antarctic coast as seen by a NASA satellite on Sept. 25, 2017. It measured 19,000 square miles

Experts have known about the mysterious ice holes, called polynya, for decades.

They stick around for weeks to months, where they acts as an oasis for penguins, whales and seals to pop up and breathe.

The biggest ever recorded appeared off the Antarctic coast in September 2017 and spanned 19,000 square miles.

Between 1974 and 1976, an area the size of New Zealand was missing from Antarctica's sea ice due to several huge polynyas that sprung up at once.

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Artist's impression of a polynyaCredit: Wikimedia

But despite numerous sightings via satellites, scientists have long puzzled over how they form.

Researchers at the University of Washington, USA, have now solved the conundrum using state-of-the-art sensors.

Strapped to floating robots and even elephant seals, the equipment tracked weather and ocean conditions around Antarctica's Weddell Sea.

Researchers found that several factors play a key role in polyna formation – but all must be present at once.

High wind speeds during heavy storms push ice around and force upward mixing of the water in the eastern Weddell Sea.

In that region, an underwater mountain known as Maud Rise forces water around it and leaves a spinning vortex above.

Analysis shows that when water at the surface is especially salty, strong winter storms can set off an overturning circulation.

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Experts strapped sensors to elephant seals as part of the studyCredit: University of Washington

Warmer, saltier water from the depths gets churned up to the surface, creating a feedback loop where ice can't reform.

"This study shows that this polynya is actually caused by a number of factors that all have to line up for it to happen," said scientist Professor Stephen Riser.

"In any given year you could have several of these things happen, but unless you get them all, then you don't get a polynya."

The study was published in the journal Nature.

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In other news, Antarctica is thinning at an extraordinary rate as experts reveal 100 metres of ice sheet thickness has vanished since the 1990s.

Another recent permafrost study found that diseases laying dormant in ancient ice could soon be unleashed due to climate change.

And, scientists have warned that two thirds of ice in the Alps will melt by 2100.

What do you think about the huge ice holes? Let us know in the comments...

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https://www.thesun.co.uk/tech/9261234/mystery-ice-holes-antarctic/

2019-06-10 15:00:00Z
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