A Kiwi-led international expedition will investigate how warming oceans could affect an Antarctic ice sheet that stores an equivalent three metres of global sea level rise.
Victoria University geologist Dr Rob McKay is heading a 30-strong team from the International Ocean Discovery Programme (IODP) who, from next month, will spend nearly 10 weeks drilling at six sites around the Ross Sea.
The drilling, reaching up to a kilometre below the sea floor at each of the sites, aims to better understand the interplay of the ocean and the West Antarctic Ice Sheet, which, according to satellite data, is losing around 150 cu km of ice each year.
It packed about 10 per cent of the volume of the 25.4 million cu km of the wider Antarctic ice sheet.
"We want to understand how the ocean and the ice sheets interact," said McKay, an associate professor at Victoria's Antarctic Research Centre, who will travel to the ice on the JOIDES Resolution, a 140m-long scientific research ship operated by the IODP.
"So what happens when you put warm water next to the ice sheets? Do they melt? If so, how quickly do they melt? And what's the impact of that melt on the oceans?"
By drilling down so deeply into the sea floor, the team would be able to gain a glimpse into the past — up to 20 million years ago — and "greenhouse worlds" that contained the same level of carbon dioxide as that now in our atmosphere.
"Using these geological records to see what the planetary response was to the current carbon dioxide levels means we can better understand what the scale of change could be for us, and what the Earth is capable of in a warmer world," McKay said.
"Antarctica today acts as a giant heat-sink that keeps the planet cold.
"If you change that, you're changing a major part of the global climate system.
"We're trying to understand what happened the last time that was changed."
If the West Antarctic Ice Sheet were to melt — as it has in the past — McKay said the global sea level would rise about three metres.
The impact from the collapse of the Eastern Antarctic Ice Sheet would be even more dramatic, because it contained enough ice to cause an estimated 20m rise in sea levels.
"The consequences of that for coastal living, globally, are obvious, but we're also trying to understand the implications for the biosphere in the Southern Ocean," he said.
"This is one of the largest biological habitats on the planet and we don't know how it will respond to these changes."
An important difference between then and now was also the fact that the increase in carbon dioxide levels that took many thousands of years to occur as part of natural cycles has happened in just a couple of centuries due to human emissions and is continuing.
No stranger to the coldest, driest, windiest continent on Earth, McKay travelled to Antarctica when he was 20 years old for his first overseas trip — which he describes as a "complete sensory overload".
Two decades later and the five years he has spent planning the current expedition are about to pay off, because he will follow in the footsteps of several pioneering Victoria University researchers.
"One of the reasons I was invited to be the co-chief scientist on this expedition is that we have a very strong link with records of previous drillings, led by Victoria," McKay said.
"It's been almost 50 years since the first drilling in Antarctica, which was carried out by scientists that included Victoria University Emeritus Professor Peter Barrett — former director of the Antarctic Research Centre.
"He revolutionised the way we view Antarctica, in terms of its geological record, and really pioneered core sample drilling on the continent.
"He developed a record that is absolutely fundamental to interpreting Antarctica's role in global climate change."
Kiwis camp out on Ross Ice Shelf
Meanwhile, another New Zealand-led team of 24 international scientists has set up a drilling site on the Ross Ice Shelf, about 350km away from Scott Base.
That expedition - led by Professor Christina Hulbe and Dr Christian Ohneiser of Otago University - is drawing on a Kiwi-built drill using hot water to bore through hundreds of metres of glacial ice to access the ocean and sea floor beneath their remote camp.
The Ross Ice Shelf is Earth's largest expanse of floating glacial ice, and is fed by glaciers flowing from the West Antarctic Ice Sheet and through the Transantarctic Mountains and by new snow falling on its surface.
The ice is continually moving, flowing away from the land and toward the open ocean, and eventually breaking off as icebergs.
At the drill site, which the scientists visited two years ago, the ice is moving as fast as two metres each day.
Oceanographers and geophysicists are installing instruments for long-term monitoring of conditions in the ocean cavity and the ice shelf, while geologists are lowering a core barrel down the hole to sample sediments on the sea floor.
A remotely operated submarine on a 3km-long tether is also being used to dive down the borehole to observe ocean, sea floor, and ice conditions in the area all around the drill site.
Back at the surface, an atmospheric physicist will install a regional network of smart weather stations and geophysicists and surveyors will use ice-penetrating radars and acoustic techniques to image internal structures of the ice shelf.
"We know that in the past, climate warming caused ice shelf and ice sheet retreat in the Ross Sea," Hulbe said.
"Now we need to find out more about the actual physical processes and the rates at which they act.
"That knowledge is one of the keys to making better projections of future change."
Ohneiser noted the Ross Ice Shelf was a "major interface" between the West Antarctic Ice Sheet and the Southern Ocean.
"At the moment the Ross Ice Shelf appears to be stable, but we don't know for sure. But we do know that it has changed quickly in the past.
"We need data from the places that are still covered by ice - not just at the easy to get to places around the edge."