Thick­ness of sea ice in Arc­tic and Antarc­tic is poles apart

The Star Early Edition - - NEWS - STEVE CON­NOR

THE FLOAT­ING sea ice sur­round­ing the South Pole may be thicker than pre­vi­ous es­ti­mates have sug­gested, ac­cord­ing to a study based on a sub­mersible ro­bot that has mapped the sea ice in three key re­gions of the Antarc­tic.

Past es­ti­mates of Antarc­tic sea ice were based on satel­lite mea­sure­ments from space, which can mea­sure its over­all sur­face area, and ice cores drilled through the sea ice from ice-break­ing ships to mea­sure its thick­ness.

How­ever, un­like the Arc­tic sea ice where ice thick­ness has been mon­i­tored for decades by nu­clear sub­marines, there are no mil­i­tary sub­marines al­lowed un­der the Antarc­tic Treat.

This means that large re­gions of the sea ice have ef­fec­tively re­mained un­ex­plored from be­low, sci­en­tists said.

With the help of a 2m-long, twin-hulled au­ton­o­mous un­der­wa­ter ve­hi­cle (AUV), sci­en­tists from the US, Aus­tralia and the Bri­tish Antarc­tic Survey (BAS) have drawn up the first de­tailed, high-res­o­lu­tion 3D map of Antarc­tic sea ice in ar­eas that were in the past con­sid­ered too dif­fi­cult to study from ice break­ers.

“The AUV mis­sions have given us a real in­sight into the na­ture of Antarc­tic sea ice, like look­ing through a mi­cro­scope,” said Jeremy Wilkin­son of the Bri­tish Antarc­tic Survey. “We can now mea­sure ice in far greater de­tail and were ex­cited to mea­sure ice up to 17m thick.

“It gave us a re­ally good ba­sis for what the ice thick­ness is at present. Over time we hope to make re­peat mea­sure­ments and build up a time se­ries to see how the sea ice thick­ness is chang­ing,” he said.

The ro­botic sub­mersible used up­ward-look­ing sonar to map the thick­ness of the sea ice over an area of 1 294 994km2 in three lo­ca­tions – the Wed­dell, Belling­hausen and Wilkes Land sec­tors of Antarc­tica.

While the sea ice in the Arc­tic has de­creased in sur­face area by about 40 per­cent over the past 40 years, the sea ice in the Antarc­tic has in­creased for rea­sons that are still un­der de­bate.

Wilkin­son said that one cause could be a change in wind pat­terns that is blow­ing sea ice fur­ther out to sea. – The In­de­pen­dent

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