Antarctic glacier’s tough stomach uncovered

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Media captionThis film illustrates the tough terrain underlying some elements of the PIG

The melting Antarctic ice stream that’s at the moment including most to sea-level rise could also be extra resilient to vary than beforehand recognised.

New radar photos reveal the mighty Pine Island Glacier (PIG) to be sitting on a rugged rock mattress populated by huge hills, tall cliffs and deep scour marks.

Such options are more likely to gradual the ice physique’s retreat because the local weather warms, researchers say.

The examine seems within the journal Nature Communications.

“We’ve imaged the shape of the bed at a smaller scale than ever before and the message is really quite profound for the ice flow and potentially for the retreat of the glacier,” stated lead creator Dr Rob Bingham from Edinburgh University.

“Where the bed is flat – that’s where we will see major retreat. But where we see these large hills and these other rough features – that’s where we may see the retreat slowed if not stemmed,” he advised BBC News.

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Damon Davies

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For weeks, the crew dragged radar gear throughout the glacier floor

The PIG is an unlimited characteristic in West Antarctica.

The glacier runs alongside the Hudson mountains into the Amundsen Sea, draining an space overlaying greater than 160,000 sq km – about two-thirds the scale of the UK.

Its remoteness makes it extraordinarily tough to review, and it’s only prior to now 20 years or so, with badistance from satellites, that scientists have realised the glacier is present process important change.

The PIG has sped up and thinned as hotter ocean waters have gotten underneath its floating entrance to soften the ice from beneath.

The grounding line – the purpose the place this entrance begins to change into buoyant – has pulled again in direction of the land by greater than 30km for the reason that early 1990s, main some researchers to imagine the entire glacier might collapse inside just a few hundred years if world warming accelerates issues.

But to have actual confidence in modelling its future behaviour, scientists have to know way more in regards to the PIG.

In specific, they should perceive higher the kind of floor over which the ice is sliding.

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A comparability of the PIG subglacial terrain and the panorama round Edinburgh

It is one of these knowledge that’s now being reported by the British crew, who dragged radar devices over the glacier in a weeks-long marketing campaign within the southern summer season of 2013/14.

Radar can see by way of a whole bunch of metres of ice to sense the topography on the base of the glacier. And though the expedition couldn’t map the PIG’s full extent, sampling was finished at key locations on the principle flowing trunk and the foremost tributaries. A complete of 1,500 sq km was imaged.

What was anticipated was that the basal rock would present lineations from the scouring results of ice that has been shifting throughout it for tens of millions of years.

What was surprising although was the dimensions of the reduction seen in quite a lot of areas.

To illustrate this roughness, the crew has produced a comparability of the PIG’s underbelly with the glacial terrain surrounding Edinburgh.

The Scottish capital was itself lined by an ice sheet 20,000 years in the past.

The well-known elevations of Arthur’s Seat and Castle Rock look puny subsequent to among the jagged options underlying the PIG.

“In one place at the bed of Pine Island, the ice mounts a cliff that’s almost vertical and some 400m high,” defined Dr Bingham.

“This would be a totally incredible feature if you could stand in front of it and see it for yourself. But it’s buried deep under the ice. At the surface of the glacier, of course, you wouldn’t even know that it’s down there because the top of the PIG is so flat.”

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Anna Hogg

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The floor of the PIG could also be flat however the radar know-how senses the hidden topography

The Edinburgh scientist believes the rock underneath the glacier should be extraordinarily exhausting to have retained such roughness.

Co-author Prof David Vaughan, from the British Antarctic Survey, says the brand new data will now convey larger refinement to ice fashions.

“The further roughness beneath Pine Island Glacier is important as a result of for the time being we mannequin the glacier in a approach that places all the pieces we all know in regards to the mattress right into a single parameter which we ‘infer’.

“This badysis begins the method of measuring these mattress properties in a way more right and extra strong approach,” he advised BBC News.

The PIG badysis was performed underneath a programme known as iSTAR. The same effort will now goal the “next door” Thwaites Glacier. This is also shedding billions of tonnes of ice annually that contribute to rising sea ranges.

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