Traversing the world’s most unforgiving continent requires a generous measure of stoicism. “We took risks, we knew we took them,” wrote the Antarctic explorer Robert Falcon Scott in 1912, trapped by a fierce blizzard in the days before he died, on an ill-fated expedition to reach the south pole. “Things have come out against us, and therefore we have no cause for complaint.”
More than a century later, elemental extremes are still an unfortunate fact of life for scientists in Antarctica. Despite three seasons of bad luck which have delayed his team’s quest to find the world’s oldest ice, the paleoclimate scientist Dr Joel Pedro remains sanguine. He has good reason to be: this summer, after multiple setbacks and a relocation, a plan years in the making is finally coming to fruition.
Pedro speaks to Guardian Australia from a site high on the Antarctic plateau, where the daytime temperature currently hovers around -30C. He is the lead scientist for Australia’s Million Year Ice Core project, which is hunting for – as its name suggests – ice that formed more than a million years ago. Bubbles of air trapped in that ancient ice will unlock secrets about Earth’s past climate, and help scientists understand the future as CO2 in the atmosphere continues to rise from human activity.
The last Antarctic season was particularly tough. To begin ice drilling, a 500-tonne convoy had to make a 1,200km traverse inland from Casey research station to the drill site in East Antarctica, called Little Dome C. But at Casey, disaster struck: half of the traverse team came down with Covid.
“No one was terribly sick,” Pedro says, but some expeditionists had to be evacuated to Australia. Little Dome C sits at 3,230 metres above sea level, and there were concerns about whether the altitude would complicate people’s recoveries. The traverse was delayed by five weeks.
Pedro and his scientist colleagues were set to fly from Casey station to Concordia, about 10km from the drill site, to meet the traverse team. But Casey, on the Antarctic coast, is prone to inclement weather – three blizzards came through, delaying the team. Time was running out, the season drawing to a close: after January, temperatures can drop to -50C to -60C, too cold to operate machinery. The difficult decision was made not to begin drilling.
Meanwhile, a European ice core project, at a site only 4km away, was making progress. Called Beyond Epica, the team of 10 countries had a few years’ head start on the Australians. Last week, they hit the bedrock beneath the Antarctic ice sheet, extracting a 2.8km-long ice core, the bottom of which contains ice believed to be 1.2m years old.
The non-starter of the 2023-24 season presented the Australians with a dilemma: wait another year to begin drilling, in the same area as the Europeans, or start from scratch at an entirely different location. New modelling and radar imaging, published in mid-2023, suggested that another location 45km away, Dome C North, contained ice that was much deeper and older – ice up to 3.2km thick, aged well over 1.2m and potentially up to 2m years old.
That turned out to be the silver lining of last season’s delay, says Pedro, who had “a lot of sleepless nights” over the decision to shift sites. The team would be drilling in Antarctica over the next five years, and analysing the ice cores in the lab for the next decade; if the new site could yield older ice than the Europeans have unearthed, scientifically it was worth the switch.
In December, a 642-tonne convoy set out from Casey station to make the overland traverse. They arrived at Dome C North, the new drilling site, 18 days later on Christmas Eve, and were subsequently treated to a Christmas party hosted by the French and Italians at nearby Concordia station. After a “pretty devastating” season last year, “it’s been so cool to actually be in the field”, says Nate Payne, the traverse team’s mechanical supervisor.
The scientific and drilling team flew into Concordia on New Year’s Eve. In the fortnight following, they erected a permanent drill shelter, a 27-metre-long structure that will stand for the next five years, housing a drill more than 8 metres long and withstanding temperatures as low as -80C.
On Tuesday, drilling of the ice core officially began. Within two days, the team was down to a depth of 80 metres. “It seems amazing after seasons where very little happened because of various logistical challenges,” Pedro says.
The team is aiming to get to 150 metres by the end of January, extracting ice cores that provide a climate record of the past 4,000 years. Over the next five years, the main drill will pull up three-metre-long cylinders of ice at a time, continuing until it hits bedrock more than 3km down.
When the ice cores come out of the barrel they are dusted off, measured, weighed and cut into one-metre increments, says Chelsea Long, a PhD student at the University of Tasmania, who is responsible for processing the cores. “They’re coming out at about -55C,” she says. “You can’t touch them with your fingers. I made that mistake this morning.
“In future seasons, because the ice is under so much pressure when it comes up, it has to come up really, really slowly, otherwise it can crack,” she says.
The ice will eventually be flown to Australia, at temperatures far below freezing, for analysis: oxygen isotopes to give a history of temperature changes; chemical analysis for traces of continental dust or clues about ancient volcanic eruptions; and, not least, changes in the level of greenhouse gases over time.
If the team can recover an ice core older than 1.2m years, it will extend the climate record beyond a period known as the mid-Pleistocene transition, when Earth shifted to shorter ice-age cycles and smaller ice sheets.
“It’s about understanding long-term climate stability and what sets the Earth’s climate state,” Pedro says. “It’ll be a very valuable addition to our understanding of Earth’s past climate, and that of course is important for testing models that we use to predict future climate.”
