KEY POINTS:
A trail-blazing team of international scientists, including several from the University of Otago, has just drilled its way into Antarctic history.
The US$30 million ($43.4 million) Antarctic drilling (Andrill) project team yesterday drilled more than 1020m into the seabed beneath the continent's massive ice sheets - probing more deeply into ancient sediments than researchers have ever done before.
"This is the first time anyone has recovered such a drill core from beneath a floating ice shelf," Otago University geologist Associate Professor Gary Wilson said. The drilling would continue until Christmas Day.
Professor Wilson the project leader said via email that the "back-to-the-future" scientific venture aimed to learn more about what effects global warming was likely to have on Antarctic ice this century, by discovering more about the ancient behaviour of the continent's ice sheets.
"We will be able to to put some tight age constraints on how long it takes for ice shelves to advance and retreat or collapse under varying conditions.
"This is all quite critical for New Zealand and particularly the South Island as both bottom and surface currents off the eastern margin of the southern South Island are generated and modulated by Antarctica."
The drill site is at the Ross Ice Shelf, 12km southeast of New Zealand's Scott Base. Before the drill had reached the sea floor it had had to travel through 100m of ice shelf and 900m of water.
Professor Wilson said: "That means that there is more than 2km of drill string now hanging off the Andrill rig.
"This is a bit of a milestone as it is the deepest drill hole ever drilled in Antarctica."
There had been challenges along the way, including "strong currents beneath the ice shelf", and initial difficulties pushing the sea riser - a wide-diameter steel pipe within which the drill runs - into the sea floor.
Since the drilling season had begun in October it was "an amazing feeling" to see the recovered core material being laid out, measured, and sampled day after day, at the rate of 30-40m a day, Professor Wilson said. Each day revealed "something new".
Three others from Otago's geology department - Christian Ohneiser, Alissa Quinn and technician Brent Pooley - are part of the more than 80-strong multinational Andrill team.
"The cores reveal a dynamic history to the region," Professor Wilson said, "with regular retreat and readvance of the Ross ice shelf in times when the planet was a few degrees warmer than today, which is probably a fairly good analogue for 50 to 100 years time."
The ongoing research was "critical to our understanding of the role of Antarctic in the global ocean and climate system [as] Antarctica drives global circulation which in-turn delivers heat and changing sea levels around the planet."
The recent "great success" reflected the skills and commitment of many people, including Alex Pyne of Victoria University of Wellington, who had designed the drilling system; Jim Currie from Antarctica New Zealand; and the drill team, provided by Webster Drilling of Porirua.
- OTAGO DAILY TIMES
