Covering an area of 487,000 sq km, the Ross Ice Shelf is equivalent to the size of Spain. Photo / File
Covering an area of 487,000 sq km, the Ross Ice Shelf is equivalent to the size of Spain. Photo / File
Kiwi scientists are soon to lead one of the most ambitious projects ever attempted in Antarctica: probing the Spain-sized Ross Ice Shelf to better understand how the frozen behemoth will respond to a warming world.
In October, a large team of New Zealand and international researchers will travel 350km from Scott Base to set up one camp in the centre of the massive shelf, and another near its grounding line, where the shelf becomes afloat.
The teams will use hot-water drilling to create two bore holes - one which will be used for a permanent observatory, where seismometers will be frozen into the shelf, and another to probe under the ice and collect samples.
This would involve sending through the hole a slim, US-built, purpose-designed remote operated vehicle to collect water samples, along with sediment coring tools to gather sea floor samples containing paleoclimate records.
Otago University geophysicist Professor Christina Hulbe said the operation - involving a dozen separate studies, three New Zealand universities and two Crown research institutes - had been in the making for years.
In 2015, she led an expedition to map out the site, before the plan was developed with scientists and groups including the New Zealand Antarctic Research Institute, Antarctica New Zealand and other major overseas organisations.
The hot water drill that will be used to blast through the shelf was built at Victoria University and tested near Scott Base last year.
Ultimately, the camp on the shelf would include a large drilling tent, a borehole science equipment preparation tent, a general science support tent, a galley, and polar tents for sleeping.
"The borehole has to be used efficiently so there will be something going on every hour of the day," Hulbe said.
"It's so much infrastructure that our engineers have drawn up a town plan."
The logistics planning meant science teams needed to provide not just the total weight of equipment they planned to send to the ice, but the size, weight and contents of every single box.
Better understanding the Ross Ice Shelf, the largest in Antarctica, and the Ross Sea below was critical to predicting what could happen to the continent under climate change, yet there was much scientists had to learn.
"We're going to be able to take a glimpse at some of the least-sampled and strangest ocean on the planet," said Dr Craig Stevens, a physical oceanographer at Niwa who will be joining the expedition.
"It's a little like opening the lid on a sea that's been totally hidden."
Stevens said the Ross Sea was odd in the sense that it was completely protected from the effects of wind by what he likened to "a massive lid of ice".
"We normally like to think of there being two kinds of ice in the oceans around Antarctica.
"There's sea ice where the air is so cold it freezes the surface skin of the ocean.
"Then there are ice shelves like the Ross - which is land ice that slides into the ocean and forms massive floating shelves. It's the cavity that is formed beneath that we'll explore."
At present, Antarctic ice shelf ocean cavities are amongst the Earth's least known domains.
The Ross Ice Shelf cavity alone contained 1.3 times the volume of the North Sea and was essentially unsampled.
More importantly, the shelf was one of three gateways through which change came to West Antarctica, and indications have shown that a warmer world would mean a significantly smaller West Antarctic Ice Sheet (WAIS), which could retreat to isolated ice caps and mountain glaciers.
Antarctica NZ field training instructor Tom Arnold tests out a crevasse-detecting radar that was used to identify drilling sites on Antarctica's Ross Ice Shelf. Photo / Supplied
Changes would be mostly wrought by water, as relatively warm circumpolar deep water coming up against the continental shelf and under the floating ice shelves.
Melting on the underside of the ice shelf was estimated to account for about half the mass loss on the Ross Sea side of West Antarctica.
In an article published by major journal Science this month, Hulbe said different warming models yielded different scenarios, but mid-range and high-range scenarios all predicted an ultimate collapse of the WAIS.
However, low-range scenarios, lower than our current global emissions, suggested this collapse isn't inevitable, and a better understanding of the difference scenarios could feed into how we set our emissions goals, and what scale of sea level rise we need to prepare for.
"Every time paleoclimate folks collect a new sediment core or develop a new analytical method that reveals more about the record, we find that the WAIS is more sensitive to small climate changes than we previously thought," Hulbe told the Herald.
"What's unclear is the rate at which the ice sheet will respond to the warming we have committed to already, and the warming we will continue to invoke in the future.
"It's not too hard to say 'sometime in the future, there will be a lot less ice in West Antarctica. It would be nice to say 'and that will happen at a rate of X over the next Y years'.
"It would be incredibly nice to say 'and if we keep the warming under Z amount, we'll only get this much'.
"The only way to get at this is to go there and observe the ocean directly.
"We will be able to contribute a uniquely Ross Sea perspective on change in West Antarctica."
The project will build on past New Zealand research in the region, including the sprawling, international ANDRILL project that recovered a virtually continuous core record from the present to nearly 20 million years ago, as well as work on grounding lines, oceanography and sea ice studies, ice physics, and computer modelling.
What was different this time was the breadth and depth of the different scientific disciplines involved - and the sheer scale of the field science involved.
"We will see and measure things that nobody has ever seen or measured before.
"Sometimes when we are deep in the details of planning, you lose sight of that. But it's really pretty remarkable.
"You don't get that many chances to do something of this scale, to drive out into the middle of a vast white expanse that goes on as flat and white as you care to imagine, in any direction you care to look, build a small science village, drill through the ice underfoot, and have a look at what's down below.
