Antarctic Ice Core: 1.2 Million Years of Climate Data 2026

In January 2026, a European research team announced a breakthrough that climate scientists had been pursuing for more than two decades. After four summers of drilling in one of the most hostile environments on Earth, they had successfully extracted a continuous ice core from the Antarctic ice sheet reaching back 1.2 million years. The core, pulled from a depth of 2.8 kilometers (approximately 1.74 miles), is the oldest ice core ever recovered by humanity. The previous record, held by the European Project for Ice Coring in Antarctica (EPICA) Dome C core, reached 800,000 years. This new core adds 400,000 years to the climate record, pushing us closer to the mid-Pleistocene transition, a period when Earth's ice ages shifted from a 41,000-year cycle to a 100,000-year cycle.

The project, officially named "Beyond EPICA – Oldest Ice," involved a consortium of 12 European scientific institutions. The drilling site was located at a remote location called Little Dome C, approximately 35 kilometers from the existing EPICA Dome C camp. The average temperature at the site during the drilling season is minus 40 degrees Celsius (minus 40 degrees Fahrenheit). In winter, temperatures plummet to minus 80 degrees Celsius. The team of 16 drillers and scientists worked in shifts, 24 hours a day, during the Antarctic summer (November to January) over four field seasons from 2022 to 2026.

The drilling process itself is a marvel of engineering. Unlike drilling through rock, ice drilling requires a specialized electromechanical drill that uses a rotating cutter head and a hollow barrel. As the drill descends, it cuts a cylinder of ice, which is then brought to the surface in sections roughly 3 to 4 meters long. Each section is immediately cleaned, labeled, and placed in insulated containers kept at minus 50 degrees Celsius. Any rise in temperature could cause the trapped air bubbles to migrate, ruining the samples. Over the four seasons, the team recovered over 1,200 individual ice core sections, each weighing about 30 kilograms.

The deepest ice, from 2,600 meters to 2,800 meters, was the most difficult to extract. The ice near the bedrock is under immense pressure and has been deformed by the flow of the glacier. The drill encountered several "ice lenses" – layers where the ice had melted and refrozen, creating hard, crystalline structures that jammed the cutter head. At one point in December 2025, the drill became stuck at 2,750 meters. The team spent 36 hours carefully heating the drill barrel with a thermal sleeve to free it. They succeeded. The final meters of ice, just 15 meters above the bedrock, were drilled with a thermal drill that melts the ice rather than cutting it, ensuring no contamination from drilling fluids.

The scientific value of the ice core lies in the ancient air trapped inside tiny bubbles. When snow falls in Antarctica, it traps samples of the atmosphere. As more snow accumulates, the lower layers are compressed into ice, sealing those air bubbles like time capsules. By analyzing the composition of these bubbles, scientists can measure past levels of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). They can also analyze the ratio of oxygen isotopes (δ18O) in the ice itself to determine past temperatures. The Beyond EPICA core provides a continuous, year-by-year (though not annual at that depth) record of these greenhouse gases extending back 1.2 million years.

Initial results, published in the journal Nature in February 2026, have already challenged long-held assumptions about Earth's climate sensitivity. One of the most startling findings concerns the period known as the "mid-Pleistocene transition" (MPT), which occurred roughly 1.2 million to 800,000 years ago. Before the MPT, Earth's ice ages followed a regular 41,000-year cycle, driven by changes in the tilt of Earth's axis (obliquity). After the MPT, the cycle shifted to a 100,000-year cycle, driven by changes in the shape of Earth's orbit (eccentricity). The reason for this shift has been a mystery for decades. The new ice core provides the first continuous atmospheric record across the MPT.

The data shows that CO2 levels during the 41,000-year cycles were generally higher, ranging from 280 to 300 parts per million (ppm) during warm interglacial periods and dropping to 220 to 240 ppm during ice ages. However, after the shift to the 100,000-year cycles, the interglacial CO2 levels dropped to 260 to 280 ppm, while glacial levels fell as low as 180 to 190 ppm. This suggests that a long-term decline in atmospheric CO2 over hundreds of thousands of years may have triggered the shift to longer, more intense ice ages. The implication is that Earth's climate system has thresholds: once CO2 drops below a certain level, the ice sheets behave differently.

But the most concerning finding for modern climate change is the rate of change. The ice core reveals that during the most rapid natural warming events of the past 1.2 million years (called "Terminations" when ice ages ended), CO2 levels increased by about 50 to 80 ppm over a period of 3,000 to 5,000 years. That is a rate of roughly 0.01 to 0.02 ppm per year. Today, atmospheric CO2 levels have risen from 280 ppm (pre-industrial) to 420 ppm (2026) in just 250 years. That is an increase of 140 ppm at a rate of 0.56 ppm per year. The current rate of CO2 increase is 30 to 50 times faster than the fastest natural warming events in the ice core record.

The ice core also provides new data on a mysterious event called the "Mid-Brunhes Event" (MBE), which occurred approximately 430,000 years ago. At that time, the amplitude of climate cycles suddenly increased, with warmer interglacials becoming significantly warmer than previous ones. The Beyond EPICA core shows that the MBE was associated with a spike in CO2 to nearly 300 ppm during the interglacial, the highest natural CO2 level in the entire 1.2-million-year record. The subsequent interglacials (including the one we are in now, the Holocene) have had lower peak CO2 levels, around 280 ppm. The fact that human activity has pushed CO2 to 420 ppm, far beyond any natural peak in 1.2 million years, is unprecedented in the record.

Another critical finding relates to the stability of the West Antarctic Ice Sheet. The ice core contains layers of "marine ice" – ice that formed when seawater froze onto the bottom of the ice shelf. The presence of marine ice at depths corresponding to 400,000 years ago and again 900,000 years ago indicates that the West Antarctic Ice Sheet partially collapsed during those warm periods, allowing ocean water to penetrate deep under the ice. These collapses happened when CO2 levels were only 280 to 290 ppm, similar to pre-industrial levels. This suggests that the West Antarctic Ice Sheet is highly sensitive and may have already passed a tipping point. The current CO2 level of 420 ppm is far beyond the threshold that triggered past collapses.

The drilling team faced logistical nightmares that are worth documenting. The camp at Little Dome C was powered by a small nuclear generator (a radioisotope thermoelectric generator) because solar panels are ineffective during the Antarctic winter and fuel transport is prohibitively expensive. The nearest supply depot was 35 kilometers away. In October 2024, a blizzard with winds exceeding 100 kilometers per hour destroyed two of the team's tents. No one was injured, but the loss of equipment delayed the drilling by three weeks. The European Space Agency provided satellite communication support, allowing the team to send real-time data back to laboratories in France, Italy, and Germany.

The ice core samples were transported back to Europe aboard the icebreaker Polarstern. The ship left Antarctica in February 2026 and arrived in Bremerhaven, Germany, in April 2026. The core sections were kept frozen throughout the journey in specialized shipping containers that maintain a temperature of minus 55 degrees Celsius. Once in the laboratory, the cores were cut into smaller sections: one third for immediate analysis (gas extraction, isotope measurement), one third for storage in a permanent archive at the University of Copenhagen, and one third for distribution to international research partners including the United States, China, and Australia.

The analysis of the deepest part of the core (below 2,600 meters) is still ongoing as of mid-2026. The ice becomes highly compressed at those depths, and the annual layers are less than 1 centimeter thick, making them difficult to distinguish. The team is using laser ablation mass spectrometry to measure chemical impurities at microscopic resolution. Early results suggest that the period from 1.15 million to 1.2 million years ago was characterized by extremely weak monsoons in the tropics, which may have contributed to a prolonged drought in Africa. This timing coincides with a gap in the hominin fossil record, raising speculative questions about the vulnerability of early human ancestors to climate shifts.

The Beyond EPICA project cost approximately 30 million euros and was funded primarily by the European Commission. The project's success has already led to proposals for an even deeper drill, targeting ice as old as 2 million years. There are known locations in Antarctica, such as Dome A (the highest point on the ice sheet), where the ice is much thicker and may contain continuous records up to 2 million years old. However, those locations are even more remote and logistically challenging than Little Dome C. A Chinese team has announced plans to begin drilling at Dome A in 2028.

Public reaction to the discovery has been muted compared to dinosaur or space discoveries, but the scientific community has hailed it as one of the most important climate science achievements of the 21st century. The 1.2-million-year ice core effectively doubles the known timeline of Earth's atmospheric composition. It provides a baseline for understanding natural climate variability that will be used by the Intergovernmental Panel on Climate Change (IPCC) for its next assessment report, scheduled for 2028.

The core also serves as a sobering time capsule. The oldest ice, from 1.2 million years ago, contains air that was last at the surface when early humans were using simple stone tools and living in small nomadic groups. That air had 220 ppm CO2. The youngest ice, from the top of the core, contains air from the 1990s (because it takes time for snow to compress into closed bubbles), with CO2 levels around 360 ppm. The difference between the oldest and youngest air in the core is a 140 ppm rise in CO2, but almost all of that rise occurred in the last 250 years. The ice core does not lie. The evidence is frozen in the bubbles.

FAQs

1. How old is the Antarctic ice core recovered in 2026 and how deep was the drill? The ice core is 1.2 million years old at its deepest point. The drilling reached a depth of 2.8 kilometers (approximately 1.74 miles) below the Antarctic ice sheet surface. This makes it the oldest continuous ice core ever recovered, surpassing the previous record of 800,000 years from the EPICA Dome C core.

2. What does the ice core tell us about past CO2 levels? The ice core reveals that over the past 1.2 million years, natural CO2 levels fluctuated between approximately 180 ppm during ice ages and 300 ppm during the warmest interglacial periods (specifically the Mid-Brunhes Event 430,000 years ago). The current atmospheric CO2 level of 420 ppm is far higher than any natural peak in the entire 1.2-million-year record.

3. Why is the mid-Pleistocene transition important and what did the core reveal? The mid-Pleistocene transition (MPT) occurred 1.2 to 0.8 million years ago when Earth's ice age cycles shifted from 41,000-year cycles to 100,000-year cycles. The new ice core shows that CO2 levels gradually declined across the MPT, suggesting that long-term drops in atmospheric CO2 triggered the shift to longer, more intense ice ages. This helps scientists understand climate tipping points.

4. How fast is current CO2 rise compared to natural changes in the ice core? The ice core shows that the fastest natural CO2 increases during ice age terminations took 3,000 to 5,000 years to rise by 50-80 ppm (0.01-0.02 ppm per year). Current human-caused CO2 rise has increased by 140 ppm in just 250 years (0.56 ppm per year). The current rate is 30 to 50 times faster than any natural warming event in the past 1.2 million years.

5. What evidence did the ice core find about West Antarctic Ice Sheet collapse? The core contains layers of "marine ice" (frozen seawater) at depths corresponding to 400,000 years ago and 900,000 years ago. These layers indicate that the West Antarctic Ice Sheet partially collapsed during those warm periods, allowing ocean water to penetrate under the ice. Those collapses occurred when CO2 levels were only 280-290 ppm, similar to pre-industrial levels, raising concerns about future collapse under current CO2 levels of 420 ppm.