Polarjournal ‹ Beyond EPICA - Oldest Ice: 1.2 Million Years of Climate History Unearthed in Oldest Ice Core

Follow us

News > Antarctic

Beyond EPICA – Oldest Ice: 1.2 Million Years of Climate History Unearthed in Oldest Ice Core

Julia Hager 16. January 2025 | Antarctic, Science


It marks a historic milestone for the European drilling project “Beyond EPICA – Oldest Ice”: the international research team successfully extracted a 2,800-meter-long ice core from Antarctica, containing at least 1.2 million years of climate history.

An aerial view of the Little Dome C research camp in East Antarctica, where the international team has been drilling for the longest continuous ice core since the 2021/2022 summer season. Photo: PNRA / IPEV

The search for the perfect drilling site in East Antarctica began around nine years ago. The Beyond EPICA team finally set up camp at “Little Dome C”, around 35 kilometers from Concordia Station (Dome C) and 950 kilometers from the coast.

After four Antarctic summer field seasons, the research team has achieved a historic milestone in climate research by recovering the oldest continuous ice core ever extracted, as announced by the Alfred Wegener Institute (AWI) in a press release on January 9.

The “Beyond EPICA – Oldest Ice” project unites institutes from ten European countries, including the AWI (Germany), the British Antarctic Survey (United Kingdom), the French Polar Institute IPEV (France), the University of Bern (Switzerland), and the Institute of Polar Sciences of the National Research Council of Italy (ISP-CNR), with the latter leading the drilling efforts.

Once a new section of the ice core is recovered, processing begins immediately. This involves rapid analyses, measuring, labeling, cutting the core into shorter sections, and splitting it lengthwise into multiple parts for various analyses. Video: Beyond EPICA

At least 1.2 million years of climate history

The 2,800-meter-long ice core stretches from the surface of the ice sheet to the bedrock below, preserving a continuous climate record spanning the past 1.2 million years. The deepest and oldest ice layers date back to the Lower Pleistocene, or Calabrian stage—a period when Homo erectus was among the dominant hominins.

The previous record for the oldest continuous ice core, dating back 800,000 years, was set by the predecessor project EPICA in 2004.

In an interview, Prof. Olaf Eisen, a glaciologist at the AWI and the University of Bremen, shares that he feels “very relieved,” as he and his team “did everything right” during the project’s preparatory phase. From 2016 to 2019, he coordinated the search for the optimal drilling site. To achieve this, scientists analyzed radar images of the ice surface to study its structure and used models to estimate its age.

He adds that the recently recovered ice core could potentially date back as far as 1.5 million years, though precise analyses will be needed to confirm this estimate.

In the lower sections of the kilometer-long ice core, the ice is so densely compressed that a single meter represents up to 13,000 years, as initial rapid analyses conducted on-site for the first time have shown.

Left: Ice core storage in the drilling camp. Photo: PNRA / IPEV Right: The progress of the drilling over the last four field seasons. Graphic: Beyond EPICA

This ice core is undoubtedly invaluable for climate research. On the one hand, it represents the first continuous archive of atmospheric carbon extending beyond 800,000 years, allowing scientists to reconstruct Earth’s past temperatures, explains Prof. Eisen.

On the other hand, he and the entire team hope that the ice, which captures the additional 400,000 years beyond the 800,000-year mark, holds the key to solving a long-standing puzzle that has fascinated climate scientists.

The slowdown of the ice age cycles

Sediment cores extracted from the ocean reveal that during the Middle Pleistocene transition, around one million years ago, the cycles of ice ages slowed from 41,000 years to 100,000 years. However, these cores do not uncover the cause of this shift.

The researchers are now placing their hopes on the oldest layers of ice in the newly recovered core. “A key variable is the carbon dioxide in the atmosphere. Since this cannot be measured directly in sediment cores from the ocean, […] it is crucial to have a continuous ice core that contains the ancient atmospheric gases,” explains Prof. Eisen. “There have been numerous hypotheses about what caused the shift from 41,000- to 100,000-year cycles. Some of these have become less plausible in recent years, and currently, all evidence points to the Southern Ocean playing a pivotal role in the carbon cycle.”

The air bubbles trapped in the ice offer valuable insights into the composition of the atmosphere in the past. Researchers are particularly focused on analyzing carbon dioxide and methane levels. Photo: PNRA / IPEV

Prof. Eisen outlines key, yet unanswered questions that the new findings may help address: What role does the Southern Ocean play? How much carbon can it absorb? What implications does this have for future carbon dioxide levels in the atmosphere? What impact might this have on ocean circulation? How did the Southern Ocean behave during this transition? And ultimately, what do these insights mean for the next three centuries?

“The Southern Ocean is the engine of the global ocean currents. It’s where deep water is formed, and if that process changes, the effects will be felt globally. And that is, so to speak, the direct link to the climate crisis that we are facing today.”

More reliable predictions

The new data from the distant past is expected not only to enhance climate models for future predictions but also, as Prof. Eisen explains, to improve our ability to identify and anticipate tipping points and states within the climate system, ensuring better preparedness.

“But it’s also possible that we are triggering other tipping elements that we previously knew little about,” he adds. “Ultimately, this data should help us look into the past and evaluate how accurately our climate models can reproduce these changes in the Earth system.”

This would also enhance the reliability of future projections across various scenarios.

Is there any older ice in Antarctica?

Even much older ice. In April 2024, Polar Journal AG reported on the discovery of 4.6 million-year-old ice in a blue ice area in the Allan Hills, also in East Antarctica, but close to the coast.

However, in blue ice areas, it is unlikely to obtain a continuous ice core; instead, you typically recover large amounts of ice from specific periods, explains Prof. Eisen. This is, of course, very valuable: for instance, if something noteworthy is identified in a 1.4 million-year-old continuous ice core from Little Dome C, which has a diameter of only ten centimeters, much larger quantities of ice from the same period can be found in a blue ice area and used for more detailed analyses.

Finding even older ice in a continuous sequence, however, is far more challenging. The Australian “Million Year Ice Core” project has relocated to a different drilling site farther from Little Dome C, following a recommendation from the Beyond EPICA consortium, which, as mentioned, had thoroughly surveyed the region to identify the best drilling locations. Drilling at this new site is set to begin, and according to Prof. Eisen, there is a possibility of discovering older ice with even better resolution in this area.

The “Little Dome C” drilling site is located approximately 35 kilometers from the French-Italian Concordia station (Dome C). A blue ice area is located in the Allan Hills. Map: Google Earth, edited by Julia Hager

The AWI and other participating institutes expect the arrival of the ice core in early summer. The top priority will be analyzing the carbon dioxide and methane trapped in the ice to reconstruct the climate history. More complex analyses, such as those of particles, will follow at a later stage. The first results are expected to be available in about a year.

When asked how he views the future in light of the increasingly frequent temperature extremes and records in the ocean and atmosphere, Prof. Eisen responds:

“Very frustrated: While we have made significant progress with renewable energies and are heading in the right direction—albeit too slowly—solar energy is now the cheapest form of energy globally. Yet, instead of accelerating this transition, we are seeing it being slowed down again. We still have every opportunity to act, and we always have a chance to take countermeasures. However, the longer we wait, the more difficult, costly, and painful it will inevitably become.”

Julia Hager, Polar Journal AG

Link to the Beyond EPICA – Oldest Ice project: https://www.beyondepica.eu/en/

More about this topic:

linkedinfacebookx
Compass rose polar journal

Join the Polar Community!

Discover our polar newsletter featuring more articles from every polar aspect as well as events and polar opportunities and Arctic and Antarctic ice charts.