An international team of researchers has successfully drilled and recovered a 2,800-meter-long ice core from Antarctica dating back to 1.2 million years ago. The sample extended so deep that it reached the bedrock beneath the Antarctic ice sheet.
The core, almost as long as 25 football fields laid end to end or six and a half times taller than the Empire State Building to the tip of its antenna, is a “time machine” that captures “an extraordinary archive of the world.” , said Carlo Barbante, coordinator of Beyond EPICA, or the European Antarctic Ice Drilling Project, the team that collected the core.
The team cut the core into 1-meter pieces stored in insulated boxes so they can be studied, said Barbante, a professor at Venice’s Ca” Foscari University and associate senior member of the Institute of Polar Sciences of the Italian National Research Council.
The core was collected at Little Dome C, one of the most hostile and extreme locations on the planet. The site is 34 kilometers from the Italian-French Concordia research station and is constantly hit by strong gusts of wind and almost constant temperatures below -40 degrees Celsius.
The ice, some of the oldest ever drilled into Earth, could provide answers to the biggest remaining questions about how the planet’s climate has changed over time.
“The air bubbles trapped inside provide a direct snapshot of past atmospheric composition, including concentrations of greenhouse gases like carbon dioxide and methane,” Barbante said in an email. “By analyzing this, we can reconstruct how Earth’s climate responded to changes in climate factors such as solar radiation, volcanic activity and orbital variations. This data helps us understand the intricate relationship between greenhouse gases and global temperature over hundreds of thousands of years and now up to 1.2 million years and, we hope, beyond.”
Scientists also hope the ice will shed light on what caused the sudden change in weather about 1 million years ago, an event that nearly caused the extinction of ancient human ancestors, according to recent research.
An icy landmark
The researchers collected the core during the fourth campaign of the Beyond EPICA — Oldest Ice project, funded by the European Commission. The campaign took place during the most recent Antarctic summer, between mid-November and mid-January. In total, experts from 12 European scientific institutions have spent more than 200 days drilling and processing the ice over the past four summers.
The program builds on the goals of the initial EPICA project, which ran from 1996 to 2008. During that time, researchers drilled a deep ice core that revealed links between climate and atmospheric greenhouse gases over the past 800,000 years. The core collected during the latest campaign marks a new milestone, creating a continuous record of Earth’s climate that goes back even further.
Studies from the original EPICA core showed that Earth’s climate experienced a 100,000-year cycle of cold glacial periods, or ice ages, interspersed with warmer periods. But that discovery didn’t match marine sediments that revealed Earth once experienced glacial periods lasting 41,000 years before 1 million years ago.
The Beyond EPICA project began in 2016 with the goal of finding older ice that could indicate why this change occurred, and the search for the right location began with the use of radar surveys.
Radio echo sounding technologies helped team members locate ice that could contain the time capsule they were looking for, said Frank Wilhelms, principal investigator in the field and joint professor at the University of Göttingen and the Alfred Wegener Institute in Germany.
“We needed a Goldilocks site — ice thick enough for a well-resolved climate record at the greatest depth, but not so thick that the oldest ice had already melted,” said Dr. Robert Mulvaney, glaciologist and paleoclimatologist at the British Antarctic Survey.
“This can happen when heat escaping from Earth’s mantle becomes trapped by a thick insulating layer of ice.” “If the ice is too thick, we could lose the lower, older layers to melt,” Mulvaney said. “So we put a lot of effort into researching candidate areas to find the right location before drilling begins.”
Little Dome C is located high on the Central Antarctic Plateau, reaching an altitude of 3,200 meters above sea level, presenting numerous challenges. The team had to work to prevent drilling failures and ensure the electromechanical core drill was progressing through the ice sheets. Each meter of ice can contain up to 13,000 years of climate data, said Julien Westhoff, lead field scientist and postdoctoral researcher at the University of Copenhagen in Denmark.
Insights from ancient ice
When team members recovered the core, they found what they were looking for. The lowest 700 feet of core above bedrock consists of ancient ice that was heavily deformed, likely mixed, refrozen and of unknown origin, the team said.
Analysis of the ice can help test theories about how it refroze beneath the ice sheet. Researchers will also determine whether even older ice, such as that from the pre-Quaternary period 2.58 million years ago, is present and provide dating of the rocks beneath the ice to determine when this region of Antarctica was last ice-free. .
“It was exciting to see the age of the ice as we drilled deeper, and especially when we learned that we were drilling into ice older than the EPICA record, which ended 800,000 years ago,” Mulvaney of the British Antarctic Survey said in a statement. “This 1.2 million year record will give us several 41,000 year glacial cycles to compare with the most recent data from the original EPICA core.”
The Middle Pleistocene Transition, which occurred between 1.2 million and 900,000 years ago, marks the fundamental change in Earth’s glacial cycles, Barbante said.
“This transition remains a scientific mystery, particularly regarding the role of greenhouse gases and ice sheet dynamics,” he said. “The Beyond EPICA ice core offers an unprecedented opportunity to directly measure atmospheric conditions during this crucial period, potentially revealing answers about why this transition occurred and how it shaped our planet’s climate system.”
During the Middle Pleistocene Transition, ice ages became longer and more intense, leading to a drop in temperature and dry climate conditions. The global population also fell to about 1,280 breeding individuals between 930,000 and 813,000 years ago and remained that way for about 117,000 years, according to a 2023 study published in the journal Science. The study authors argue that this event “brought human ancestors close to extinction,” but others are more skeptical.
Regardless, the ice core may contain evidence about why the change in the length of ice age periods occurred.
There’s something in the air (bubbles)
Ice cores contain layers of snow that have been compressed over time, trapping air bubbles and particles that can be analyzed to reveal how Earth’s temperature and atmosphere have changed.
They can help scientists understand how Earth’s climate has behaved in the past to better predict how things might change in the future — and provide context for how our planet responds to different concentrations of greenhouse gases.
“Antarctic ice cores are like Rosetta Stones,” said Jim White, Craver Family Dean of the College of Arts and Sciences at the University of North Carolina at Chapel Hill, in an email. “They are unique in that they speak the language of temperature as well as the language of CO2 levels, allowing us to see how these two key climate variables interact.”
White was not involved in the ice core recovery. But he said ice has the potential to provide a wealth of information “about the fundamental dynamics of climate change on our planet, and the importance of this cannot be underestimated.”
While preliminary analysis took place on site, the ice core slices will be transported back to Europe aboard the Laura Bassi icebreaker in specialized refrigerated containers to maintain the perfect temperature. Barbante predicts the research will be a multi-year effort as scientists delve deeper into measuring the concentrations of gas and dust particles within the ice.
Meanwhile, the Beyond EPICA project, as well as other international associations, will look for older ice that could reveal longer climate records. But such efforts will require more advanced technology and planning, Barbante said.
“We need to find other places in Antarctica where we can recover continuous climate records similar to what we are studying,” he said.
