New 228-Metre Antarctic Core Reveals 23 Million Years of Climate History

In the severe stillness of East Antarctica, a drill has retrieved a frozen chronicle reaching far beyond the span of human history.

Beneath layers of wind-blasted ice and age-old dust, researchers have recovered a record-breaking ice core extending back tens of millions of years. The discovery has energised research teams around the world, offering unusually valuable evidence of how Earth’s climate operated long before people existed.

What a 228-metre Antarctic core really represents

At 228 metres long, the new Antarctic core contains roughly 23 million years of environmental history, based on preliminary dating estimates. Every narrow column of ice contains imprisoned bubbles of ancient air, frozen particles and faint chemical signatures.

Together, these details make the core an unbroken record of earlier climates. Snow accumulated each year, became compressed and sealed traces of the atmosphere overhead into place. Across millions of years, these deposits built into frozen layers of stratigraphy that researchers can interpret as a slow-moving documentary.

Every metre of this core spans roughly 100,000 years of Earth’s climate story, compressing entire geological eras into a few centimetres of ice.

Teams representing several countries are likely to share access to the core, while initial work will concentrate on greenhouse gases, volcanic events and changing ocean circulation. For scientists studying climate patterns across vast timescales, this is the sort of evidence normally found only in their ambitions.

Why 23 million years matters for climate science

Most Antarctic ice cores already available document the past 800,000 years, an interval largely shaped by ice-age cycles recurring approximately every 100,000 years. Reaching 23 million years into the past takes this new record into an entirely different climatic period.

Scientists anticipate that the deepest, oldest sections will preserve evidence of:

• Warmer intervals in which Antarctica’s ice sheet contracted substantially
• Sudden cooling episodes associated with altered ocean gateways
• Natural carbon dioxide fluctuations well beyond those recorded in recent cores
• Dust and ash produced by ancient volcanic and desert activity

The core covers periods when Antarctica was partly free of ice, sea levels stood higher and the planet was responding to changes in continents and ocean basins. This background is significant now because human activity is driving atmospheric greenhouse gas concentrations into levels unseen for millions of years.

By matching ancient CO₂ levels with temperatures and sea levels, researchers gain a reality check on how sensitive Earth’s climate system truly is.

Inside the frozen archive: what scientists are looking for

Trapped air bubbles as time capsules

The air enclosed within the ice is among the core’s greatest attractions. These minute bubbles provide direct samples of former atmospheres. Scientists melt small sections of the core in a vacuum, then use highly accurate equipment to measure the released gases.

Their attention will centre on:

• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous oxide (N₂O)
• Noble gases that can help reveal ancient temperatures

By charting the rises and falls of these gases, researchers aim to establish how rapidly the planet reacted to natural variations in solar radiation, orbital cycles and tectonic change.

Chemical fingerprints of ancient storms and oceans

Ice also retains chemical evidence transported by winds and oceans. Salts, dust and isotopes held in the core can show how storm tracks shifted, as well as how sea ice advanced and retreated over time.

Signal in the ice	What it tells scientists
Oxygen isotopes	Earlier temperatures and ice volume
Sea salt particles	The reach of sea ice and storm strength
Dust concentration	Continental aridity and wind intensity
Sulfates and ash	The timing and force of volcanic eruptions

Using these indicators together allows scientists to reconstruct more than broad averages. They can also identify rapid-change events, including abrupt cooling following major eruptions and sharp bursts of warming.

A record that could reshape projections

Climate modellers are paying close attention. Simulations of future warming rely on checks of whether they can recreate climate changes from the past. So far, those assessments have largely drawn on the last 1 million years, which was comparatively cool beside some earlier epochs.

The new Antarctic core offers a test run of how the climate system behaved when CO₂ and global temperatures were closer to where humanity might be heading this century.

Should models successfully reproduce the variations captured by this core, confidence in forecasts of heatwaves and sea-level rise will increase. Should they not, researchers will revise the models, particularly the components representing ice-sheet collapse and feedback loops involving clouds and oceans.

Lessons for sea-level rise

One issue is especially prominent: how fast can major ice sheets break apart as temperatures rise? Geological evidence indicates that sea levels were several metres higher during certain warm intervals 10–20 million years ago.

By linking these sea-level estimates with exact CO₂ readings from the core, scientists hope to reduce the probable range of future change. For coastal planners from Florida to Bangladesh, such findings feed directly into assessments of long-term risk.

How the drilling was done in such an extreme environment

Drilling 228 metres into Antarctic ice is far from straightforward. The location is likely to be on a stable East Antarctic plateau, selected to achieve maximum age while preserving undisturbed layers. Crews work in temperatures far below freezing and have only brief periods of workable weather.

Engineers employ a purpose-built drill that cuts neat cylinders while keeping the ice as cold as possible. Each core section, commonly about one metre in length, is brought to the surface, recorded and placed in insulated containers.

The ice is then transported in refrigerated containers to laboratories that may be thousands of kilometres away. Strict handling procedures are essential, as even minor temperature changes may crack the core or obscure its sensitive chemical gradients.

Key terms that help make sense of this record

When scientists discuss ancient climate evidence, several technical concepts appear repeatedly. Two are particularly helpful.

Paleoclimate: This describes climates that existed before humans took direct measurements. Scientists reconstruct them through natural records including ice cores, tree rings, lake sediments and corals. Every type of archive has advantages and limitations, which is why long records such as this new core are so prized.

Climate feedbacks: Feedbacks are mechanisms that either strengthen or reduce change. For example, warming decreases ice cover, revealing darker surfaces that take in more sunlight and therefore produce further warming. The new core can help reveal how powerful these feedbacks were in the distant past, providing indications of how they could operate during present-day warming.

What this means for everyday life, far from Antarctica

A core extracted in one of Earth’s most isolated regions may seem remote to someone in London, New York or Lagos. However, the information preserved in its ice is directly connected to everyday issues, including food costs, flood danger, heatwaves and energy systems.

When models include long-term records of this kind, they can estimate more effectively how stable monsoon patterns may be, how storm belts could move and how often destructive extremes might occur. Insurers, urban planners and farmers’ unions all use such assessments, whether or not they do so directly.

There is a psychological dimension as well. Evidence covering 23 million years puts current change within a much wider narrative. It demonstrates that Earth’s climate has always changed, while also showing that major transitions generally occurred over thousands of years rather than decades. The pace of current warming is therefore striking, potentially intensifying arguments about how quickly societies should adapt and reduce emissions.

The Antarctic core does not provide policy, but it offers a timeline against which human choices in this century will be judged by future scientists.

As early findings from this record begin to appear in journals and at conferences, they are likely to prompt further model revisions, updated sea-level estimates and new questions about thresholds that must not be exceeded. For the moment, the 228-metre cylinder remains in laboratory freezers, with its account only beginning to be deciphered.