If you take an ice cube out of your freezer, you’ll see that it’s full of tiny bubbles: microscopic pockets of air that were trapped in the water the last time you refilled the ice cube tray, a week or a few months ago. Pluck a piece of floating glacial ice out of the water on an Antarctic cruise and you start coming into contact with even deeper time, hearing that fizz and pop of air bubbles escaping that were frozen hundreds or even thousands of years ago.
Reach back even further and the ice has more stories to tell. Incredibly, Antarctica is home to ice that is more than a million years old. What secrets might it contain? To find out more, we spoke to Professor Carlo Barbante about the Beyond EPICA project, and its quest to drill this ancient ice – and what that can tell us about our deep past as well as our future in a time of rapid climate change.
Reconstructing historic climates
Beyond EPICA is a European science consortium that hopes to use the gases trapped in this million year old ice to better understand our planet’s ancient climate. Barbante, the project’s director, explains to me that the current programme builds on the success of the earlier European Project for Ice Coring in Antarctica from nearly two decades ago.
‘This was an iconic project that revealed the climate of the past over the last 800,000 years, including changes in temperature and forcing factors like greenhouse gases,’ he said. EPICA was able to extract ice cores reaching back nearly 800,000 years, covering eight glacial periods roughly every hundred thousand years when the planet saw rapid cooling.
The information held by the atmospheric gases trapped in this ancient ice proved to be vitally important data for modelling how our climate responds to continuing greenhouse gas emissions. But the data could only reveal so much. Go back a little further in time to a million years, and the gap between glacial and interglacial periods becomes far shorter: 40,000 years instead of 100,000. Beyond EPICA was designed to find ice exactly that old so it can be studied in the laboratory.
‘We must know how the climate worked during that period to better understand what is happening today,’ Brabante told me, so we can understand how extremes of greenhouse gases have historically affected the planet.
‘and to put in the right perspective changes in the greenhouse gases and temperature and the sensitivity of the planet to the greenhouse gas forcing.’
Looking for ancient ice
The first challenge for the project was to find ice that was old enough to investigate. As any visitor to Antarctica can tell you, ice here is like a living thing, constantly on the move. For the deep interior, unimaginably vast ice sheets slowly move towards the coast, and glaciers pour slowly but inexorably down from mountains to eventually calve into icebergs in the sea. And when ice moves it can shear and leave part of its history behind.
Beyond EPICA’s challenge was to find ice that was static enough so that it had survived intact to leave behind an unbroken record reaching back far enough into the past.
‘We drove for more than 20,000 kilometres back and forth,’ said Barbante, looking for just such an area of ice. The team also carried out aerial surveys, using radar that was able to look inside the ice sheets to see how deep it was and to disentangle the information about how the ice was layered far below the surface.
Eventually the team chose a site they called Little Dome C, which sits at an altitude of around 3200 metres (10,500 feet) but where the ice lies undisturbed to a depth of 2750 metres (9022 feet). The site is a short flight from Concordia Base, a research station run by the French and Italian polar science agencies. Barbante laughs when he tells me that thanks to Concordia’s joint nationality, it’s regarded as having the best food anywhere in Antarctica – even once garnering a commendation from Lonely Planet.
How to drill a deep ice core
Drilling for ice that’s so deep is no easy task under the best of conditions, let alone at altitude in Antarctica where temperatures regularly drop to -35C (-31F) and below. Barbante explains how the team goes about it inside the drilling tent at Little Dome C.
The business end of the drill is a long metal tube with a cutting head on the bottom, where the ice core is collected. Behind this is a chamber that collects the tiny ice chips created by the drilling and at the top of the tube is the motor that drives the extraction. Finally, a long cable runs from the drill all the way up to the surface.
‘It’s a long journey to go down there! Barbante reminded me. ‘It takes about two hours to go down and drill and then come back. Every time we drill, we penetrate for about four meters and then have to pull up the apparatus, so it’s a long, long process.’ On a good day, the team can drill between 20 to 30 metres in a day,
At the end of every session, the drilling tube is opened to reveal a long cylinder of ice, four metres in length. It’s the tiny layers contained within these cores that hold the vital information about the prehistoric atmosphere. When you’re dealing with such ancient ice, there’s an awful lot of information packed into each core. ‘Every meter of ice contains about 15,000 years of information,’ Barbante told me.
The core is cut into four pieces so it can be processed later in a laboratory, then the drill is reassembled to get it ready to take another bite out of the ice. So it goes, four metres and 60,000 years at a time, getting deeper and deeper. Barbante hopes that the project will soon be reaching the bedrock, which was last exposed to the air 1.5 million years ago.
International cooperation
In total there are six projects across Antarctica drilling for ancient ice, although Beyond EPICA hopes to be the first to drill past the totemic million year barrier. ‘Let’s say it’s a fair competition,’ he said, pointing out that the different groups (from Australia, the USA, Russia, China and Japan) all work together under the umbrella of the International Partnership for Ice Coring in Antarctica, which is called IPICS. ‘We collaborate a lot in sharing data, facilities and ideas.’ The idea of a competition to be first to drill the oldest ice makes Barbante grin. ‘It’s like a rugby match, you know? We fight during the match and then we go drinking together.’ The knowledge that every team faces the same challenging conditions inspires everyone to pull together.
‘They are doing extraordinary work, you know, working from eight o’clock in the morning to midnight. The conditions there are really tough. There’s very thin air so everything you do is very heavy, and on top of that you’re working at -35C in the drilling trench. At the beginning of the season, it was -55C (-67F)! It’s really demanding. So we owe a lot to [our field teams].’
From here, the cores are transferred to European laboratories, maintaining a constant -50C (-58C) cold chain so that the precious sample within can be analysed to build up a picture of the ancient climate. When the results are published, they’ll be available for all climate scientists to use.
Past and future climate
In January 2025, Beyond EPICA was able to announce that it had successfully hit the bedrock and was able to obtain ice cores that were a staggering 1.2 million years old: the oldest ice ever extracted. The European consortium had won the race – but by helping to create a better picture about how our planet’s atmosphere and climate has changed in the past, all of science will be the winner. The precious ice cores are now on their way back to laboratories across Europe so that the analysis can begin in earnest.
‘These data we are hopefully providing with the new oldest ice will be instrumental to improve our knowledge about the past,’ said Barbante. But as the world faces an increasingly uncertain climate, this information can also help arm climate scientists with better models for the years ahead. The things that we will learn from the oldest ice will be literally transferred into our knowledge for better shape in the future,’ said Barbante. Looking deep down towards the bedrock far below the ice at Little Dome C, it’s a reminder that we have to know where we’re coming from to understand where we’re heading.
‘There is a lot of our past in our future,’ he concludes.
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