00-ice-core.png

Hunting Antarctica's Holy Grail, Deep Beneath the Ice

An ambitious experiment to drill into the ice sheet and travel a million years into the past.

Joel Pedro is not supposed to be sitting in a green van on Antarctica's Law Dome. Joel Pedro is supposed to be more than 600 miles closer to the heart of the continent — and about 6,000 feet higher up. 

Not that you'd notice the difference. 

Unless it's a particularly clear day the landscape at Law Dome, a 4,500-foot hill of snow on the eastern fringe of Antarctica, looks pretty much identical to the one at Little Dome C, where Pedro was supposed to be. White snow crunches under boots, white clouds roll overhead and, on the horizon, the two meet. It's like being in space, with the colors inverted.

But Pedro, an ice core scientist with the Australian Antarctic Division, isn't at Law Dome for the view. He's interested in what lies beneath the surface. 

As the lead scientist on Australia's Million Year Ice Core project, Pedro and a team of engineers and researchers were slated to begin a multiyear drilling operation at Little Dome C over the 2021/22 summer season. It would have been the first tentative steps toward recovering the oldest continuous ice core from the Antarctic.

Ice cores allow scientists to see backward through time and understand the history of the Earth's climate and ice ages. They also present an opportunity to rewrite what we know about the Antarctic, helping scientists to predict how climate change might affect our future. Retrieving a million year old ice core is one of the holy grails in Antarctic science and a grand challenge of international ice core research. Australia's Antarctic Program is trying to rise to meet it.

But Antarctica has other plans.

An Adelie penguin stands in front of Australia's Casey Station. In the distance, you can see the lower fuel farm and the station's Red Shed.

Casey Station is a major thoroughfare for Australian Antarctic Division scientists heading deeper into the continent.

Jackson Ryan/CNET

I met Pedro at Australia's Casey Station, a mud-and-snow village tucked into east Antarctica's Windmill Islands, just before he was scheduled to leave for Law Dome in January. He was exhausted and deflated. The "A Factor," a mythic disruptive force most expeditioners blame for unexpected mishaps in Antarctica, had struck: Menacing weather prevented flights from the station to Little Dome C, leaving Pedro and his team waiting for clear skies.

Read more: Journey to Antarctica Aboard One of the World's Most Advanced Icebreakers

But it wasn't just the A Factor that threw the mission into chaos. The C Factor, COVID, slowed the project to a halt when omicron was discovered at a Belgian base in December. Pedro and his team were expecting to travel to the French-Italian Concordia base en route to Little Dome C, but the base shut down and barred new arrivals. It was the second year running that COVID had thrown the project's plans into disarray.

Once it became obvious the team wouldn't get out to Little Dome C, they changed tack, deciding to head out to Law Dome (the "dome away from dome," Pedro jokes) to test their ice coring drill for the first time in Antarctic conditions. 

A map of Antarctica against a light blue ocean. The Australian Antarctic Territory is marked in yellow. Three year-round Australian Stations are marked in red.

A map of Antarctica showing the approximate location of Little Dome C (blue circle) in relation to the three Australian Antarctic Division outposts (red squares)

AAD/CNET

But as Pedro's team was making the 30-mile trek to Law Dome, a group of European scientists and engineers were setting up camp just three miles from where the Australians had hoped to be. Their drill had already made its way through the surface of the ice.

In the hunt for the million-year core, Pedro's team was losing ground. 

A voyage through time

On Valentine's Day in 1990, as NASA's Voyager I spacecraft was 3.7 billion miles from Earth, engineers spun the probe around and pointed its camera toward home. It snapped a photograph of the planet suspended in a beam of light against the emptiness of space. The Earth, less than a pixel in size, appears a faint blue color thanks to our atmosphere; a Pale Blue Dot.

p36254
Enlarge Image
p36254

The "Pale Blue Dot" image snapped by NASA's Voyager I. The Earth is faintly visible a speck of light in the yellow sunbeam.

NASA/JPL-Caltech

When Pedro stares down into the ice, he's reminded of the photograph. "When you look down a borehole, there's this really rich, deep blue," he notes. Light that penetrates the ice pack bends its way to your eyes, illuminating molecules frozen in time for years, decades — or even longer.

"You are looking back in time," Pedro says.

Antarctica is a chief record-keeper for the Earth. Its ice sheet, stable for millions of years, acts as a time capsule; a way to study the atmosphere of the planet as it was eons ago. Scientists have been drilling down into the ice for decades, fishing out slender cores less than 5 inches thick. 

Contained within each core are bubbles that formed and froze as the ice compressed over time. Cracking open a bubble and analyzing the chemistry inside reveals the levels of key Earth gases throughout history. Nitrogen, oxygen, carbon dioxide, methane and other gases are exquisitely preserved. Assessing their concentrations has allowed researchers to reveal how the amount of greenhouse gases in the atmosphere has changed over hundreds of thousands of years, long before humanity began artificially raising them. 

"It's probably the most pure recorder of environmental information of any paleoclimate archive," says Tas van Ommen, an ice core scientist at the Australian Antarctic Division. 

The oldest continuous ice core comes from Dome C, right where Pedro was supposed to start drilling over the 2021/22 summer season. It was obtained by the European Project for Ice Coring in Antarctica, or EPICA, in the early 2000s and was a watershed moment in Antarctic ice core science

The core helped strengthen the argument that CO2 levels and temperature are tightly coupled. When CO2 rises, so does temperature. It also revealed concentrations of CO2 have never been as high over the last 800,000 years as they are today. 

Looking down a borehole you see a small black circle at the centre of the image surrounded by rings of blue light

A borehole from ice core drilling at Law Dome in 2015

Gordon Tait/Australian Antarctic Division

Scientists hope to extend the record even further back in time and not just to keep themselves in a job, jokes van Ommen. "We've known from the marine sediment record that something pretty cool and interesting happened [on Earth] around a million years ago," he says. 

Sometime between 1.2 million and 800,000 years ago, the planet underwent a revolution. Before this time, Earth experienced an ice age, a period of cooler temperatures and accelerated ice sheet formation, once every 41,000 years. But for the last million years, the ice age cycles have been operating on 100,000-year cycles. Something changed. Scientists aren't sure what.

Antarctic ice cores should tell us what the planet was like during this transition period. The carbon dioxide concentrations trapped in ice core bubbles could reveal why the timing changed so dramatically – and potentially help us understand how human activities could further disorder that system. 


The first day Pedro and the Australian team spent out on Law Dome in January, the A Factor struck again. 

A blizzard descended on their site, confining the five expeditioners to a shipping container-like unit where they shared coffee and stories as wind battered the walls. Fortunately, the blizzard blew through in less than two days and, finally, they were able to get out onto the ice.

Portable vans and a tractor rest on top of white snow at Law Dome in Antarctica

Testing the drill involved setting up camp at Law Dome during the 2022 summer. Here the team stopped at D11, a waypoint on the route to Law Dome's summit, that sits about 2,300 feet above sea level.

Joel Pedro/AAD

Once the skies cleared, the team began to test their ice coring drill, the Eclipse, for the first time but — and perhaps you should expect this by now — it didn't proceed without fault. "We did run into a couple of issues," Pedro says. After a little extra machining and tinkering with drill bits, the team were able to drill down about 65 feet, giving Pedro a look down at the pale blue borehole once again.

The test functioned as something of a practice run for the work the team will do over the next five years. Getting hands-on time with the drill, in Antarctic conditions, will make the operation more efficient next year. And yet, even though Pedro says the test was "a bloody roaring success," he doesn't shy away from the disappointment of not making it out to Little Dome C. 

Little Dome C is a "special spot," he says, because it contains some of the oldest Antarctic ice we know of. 

Preliminary work has identified a site that contains extremely old ice at Little Dome C. But it's not as simple as just pointing your drill down and pulling up a core. In trying to find a million-year-old ice core, scientists run into three problems. The first is that there's only limited time to drill each year. 

In winter, Little Dome C can reach temperatures of minus 112 degrees Fahrenheit. It's simply too cold and too dark to work through the winter, which is why the ice core projects are expected to take up to seven years, making use of the limited summer season between November and February.

A man in red overalls and a black shirt, black sunglasses and a grey beanie stands with a large ice-coring drill.

Etienne Gros poses with the AAD's ice-coring drill. Gros is a design manager at Icefield Instruments and helped design and test the new drill at Law Dome in 2022.

Joel Pedro/AAD

The second is that when you get far enough down into the ice, natural heat emanating from below the surface of the Earth disturbs the bottom of the ice. The million-year record that lurks deep beneath the surface of the ice can literally melt away.

The third is the movement of the ice sheets. The frozen masses are slowly moving off Little Dome C, and, as ice jostles together, it can fold up on itself. The timeline trapped in the ice cores then becomes jumbled and out of order. If you think of the ice sheet like a diary, it would be like finding dates from August dropped into the middle of December.

Beyond EPICA

While Pedro's team was testing their drill at Law Dome over the summer, Europe's Beyond EPICA team were getting to work at Little Dome C. Their camp, a small village of tents and shipping containers erected above the ice, lies about 20 miles from Concordia station in the heart of East Antarctica. 

The preceding European project, EPICA, hoped to retrieve a 400,000-year-old ice core in the late 1990s. Carlo Barbante, an Italian ice core scientist from Ca' Foscari University in Venice who worked on the project, says the team was surprised when it discovered it had actually recovered an 800,000-year-old ice core after drilling down 10,465 feet. 

A wooden sign is erected in the snow that says "Little Dome C"
Enlarge Image
A wooden sign is erected in the snow that says "Little Dome C"

There's only one road into Little Dome C.

Carlo Barbante/PNRA/IPEV

That age put them smack in the middle of the Mid-Pleistocene Transition, the scientifically intriguing period of time when Earth's ice age intervals seemed to be changing. They knew they needed to go further. "We realized there was information we were missing in the ice," says Barbante. 

After scanning over 12,000 miles of ice near Concordia station with surface-penetrating radar from the air, they located the spot on Little Dome C where the team believes 1.5-million-year-old ice might lurk. The goal is to reach the bottom of the ice sheet sometime in 2025. 

Two months after drilling began, Beyond EPICA had reached a depth of about 425 feet before packing up for the season. On its journey to 1 million years in the past, the team had traveled back in time by just 3,000 years – a fraction of time, sure, but a promising start Barbante says the team will build on in the coming summer season. 

Having spent over two decades in one of the planet's most extreme environments drilling through ice, the Beyond EPICA team has one clear advantage over the Australian team: experience. Australia is no slouch, mind you – it has worked at Law Dome for decades and extracted cores from 4,000 feet below the surface, resolving records that stretch back almost 100,000 years, but working out at Little Dome C poses a far greater challenge. 

csm-barbante-pnra-ipev-sitrep10a-6abb5a037c.png

Carlo Barbante took this photo of the Australian Million Year Ice Core project base at Little Dome C from the Beyond EPICA camp. On the horizon you can see two small boxes -- the first signs of future endeavors for the Australian crew.

Carlo Barbante/PNRA/IPEV

The European contingent also has much better access to its drill site because the French-Italian Concordia base is just 30 miles away. The Australian journey to Little Dome C is, at least initially, going to be much more difficult, requiring a 750-mile traverse inland from Casey station on the edge of Antarctica. It's unlikely they'll encounter crevasses, but the two-week journey will test the resolve of expeditioners and engineers and there's also the ever-present threat of the A Factor lurking just over the horizon.


Competition fueled early exploration of Antarctica, particularly during the Heroic Age at the turn of the 20th century. Robert Falcon Scott contended with Roald Amundsen to become the first person to reach the South Pole. Other explorers, like Ernest Shackleton, chased the glory of being the first to traverse the continent from "sea to sea." (Shackleton did not succeed.)

Racing is a key part of the mythology of discovery in the Antarctic, but for the last 60 years, collaboration has been key to unraveling the continent's many secrets. The Antarctic Treaty, signed in 1959, stipulates the region should only be used for peaceful purposes and that scientific results should be exchanged and freely available. It's against this backdrop the hunt for the million-year ice core takes place.

Barbante says the European contingent wants to "bring ice back as soon as possible" but isn't drawn into discussions about racing the Australians for a million-year core. 

It's the same for Pedro and van Ommen, with both insisting it's really not a race. "We fully expect, given we're up against a 14-nation consortium of highly practiced Europeans, that they will be the first team to get the oldest ice back," van Ommen says. There's no shame in being second. The two teams need each other.

Their drill sites at Little Dome C are separated by just three miles of ice – Barbante notes you can actually see the Australian camp on the horizon – and the cores the teams extract will be used to validate and verify what the other team finds below the surface.

When I spoke with Pedro in February, he said he felt no jealousy about the progress the European team had made during the 2021/22 season. The Australian project, he says, won't set its timeline against that of the Europeans. "We're much better off to run our own race, do things well and do things thoroughly," he notes. Comparison is the thief of joy – especially when you've just spent two months battling Antarctic winds and COVID-19. 

csm-stocker-pnra-ipev-sitrep5-16d37e0bc6.png

Gregory Teste, a member of the Beyond EPICA team, cuts into a freshly drilled core in the camp at Little Dome C.

Stocker/PNRA/IPEV

It's not just Australia and Europe vying for the million-year core, either. Barbante notes that there are efforts by the US, Chinese, Russian, Korean and Japanese Antarctic programs to retrieve ancient ice, too.

China's program is taking place at the country's remote Kunlun Station, near a region known as Dome A – which includes the highest point on Antarctica. The drilling team's operation takes place underground each year and began coring as early as 2013. However, recent data suggests the oldest ice at the site only reaches back 800,000 years, and the ice coring team has experienced several setbacks including problems with the drill and cabling. It's now expected to reach the bottom of the ice sheet at Dome A in 2026.

Drilling ice in the Antarctic isn't like drilling into a wall to hang a painting, either. As China's engineers found out, it's not easy. The EPICA team experienced a similar drilling setback in 1999. Even the test drilling Pedro performed at Law Dome didn't proceed without flaw, requiring some tinkering in the Casey Station workshop. 

So while the glory of being the first to travel back in time 1.5 million years no doubt drives progress for all nations, the race itself isn't against each other – it's against a continent constantly trying to stop you. 

A 2-million-year ice core?

Around 34 million years ago, as carbon dioxide levels on Earth plummeted, Antarctica became a frozen desert. That means even more ancient history lurks beneath its great white ice sheets.

In 2019, researchers discovered 2-million-year-old ice in Antarctica's Allan Hills, a unique area where strong winds blow away snow that settles on the surface. Ice flows differently here too, butting up against mountain ridges and exposing ancient relic ice.

The scientists were able to analyze carbon dioxide and methane concentrations from the ancient ice they'd collected, drawing conclusions about the Antarctic temperature at that time in Earth's history. Tas van Ommen, the ice core scientist from Tasmania, says the research is "really cool," but this kind of discontinuous ice core can't be dated as accurately as the cores retrieved in drilling projects like Australia's or Beyond EPICA's, and the preservation of gas is uncertain.

"It's giving you a piece of the jigsaw," van Ommen notes, "but if you really want to understand processes, cause and effect and the way things evolve, it's much harder if you just get little jigsaw pieces."

Just how far back could we go with a continuous core? "Short answer is we don't know," says Pedro. Theoretically, older ice might exist closer to the base of the ice sheet, but there are some constraints. The ice at the lowest depths is compressed and highly thinned so it's much harder to resolve different layers and time periods. There might a whole jigsaw down there, but the pieces have been folded in on themselves. 

The drill descending into the dark down a borehole which reflects a brilliant, deep blue

The Eclipse drill descending the borehole at Law Dome. Soon, it will be descending at Little Dome C.

Joel Pedro

That makes the continuous records the Australian and European teams are hunting for some of the most valuable ice on the planet. In the coming decades, multiple generations of scientists will venture into the underland, cracking open ancient ice and spilling its gases to travel back to a world that exists frozen in time. 

It's this world that will provide scientists with the knowledge of how delicate our climate system is, what might tip it from one state to another and how, in the face of rising temperatures, we might be able to mitigate the worst effects of climate change. 

When Pedro finally stares down the completed borehole at Little Dome C and sees the blue light bounce off its smooth sides sometime in the future, he'll be thinking of the Voyager spacecraft pointing back at the Earth and taking its famous photo. The faint blue glow of deep time will stare back at him, underscoring the need to preserve and cherish our pale blue dot – the only home we've ever known. 


CNET travelled to Antarctica with the support of the Australian Antarctic Program.