What Secrets Does 1.5M-Year Ice Hold About Climate?

Scientists recently received ice cores from East Antarctica believed to be up to 1.5 million years old, the oldest ever collected. This rare find offers a continuous timeline of Earth's climate, preserving secrets that could transform our understanding of glacial cycles, greenhouse gases, and dramatic planetary shifts.

Unlocking the Climate Time Machine

Extracted from Little Dome C at depths reaching 2.8 kilometers, the new cores arrive thanks to the international Beyond EPICA Oldest Ice project. Unlike sediment records, these ancient strata trap tiny bubbles of ancient air, directly recording past concentrations of greenhouse gases like carbon dioxide and methane.

The data spans well beyond earlier Antarctic ice core findings, unlocking firsthand views of how Earth’s climate worked twice as far into the past.

Did you know?
The newly collected Antarctic ice cores are more than twice as old as any previously analyzed ice, extending our view of Earth's direct climate record far beyond current data.

Probing the Mid-Pleistocene Transition

Roughly a million years ago, Earth’s glacial-interglacial cycles underwent a profound change: the planet shifted from a rhythm of 41,000-year cycles to one dominated by 100,000-year ice ages.

Scientists view this period, the Mid-Pleistocene Transition, as one of the greatest puzzles in paleoclimate science. With these newly recovered samples, researchers expect to capture a clearer picture of how and why this shift occurred by reconstructing a timeline of atmospheric carbon dioxide, methane levels, dust content, and temperature trends.

This reconstruction will allow investigation of the mechanisms driving longer, more severe climate intervals and a better understanding of factors like ocean carbon exchange, feedback amplification, and evolving thresholds of ice sheet stability.

What the Ice May Reveal

The analytical process begins with continuous flow analysis, a technique where small pieces of ice are gradually melted and dissected to measure chemical elements, isotopes, and ancient air bubbles.

Unlike rock or sediment cores, which provide indirect clues, these samples directly preserve the atmosphere of past worlds.

Researchers will focus on resolving temperature records using oxygen and hydrogen isotopes, identifying tiny volcanic ash layers for timeline control, and examining particles like dust for insights into wind activity and desertification in other regions of the planet.

The 1.5 million-year timeline is expected to reveal details about previous peaks and valleys in atmospheric greenhouse gas levels, the speed of warming events, and unexpected tipping points.

One objective is to determine whether abrupt shifts like those seen in modern decades ever occurred naturally before, especially when matched to comparable levels of CO₂.

Climate Lessons for Today

Today’s carbon dioxide levels have soared to more than 420 parts per million, already exceeding by over 50 percent the highest values observed in any Antarctic core from the past 800,000 years.

That makes this newly recovered deep-time archive especially relevant as scientists evaluate whether current warming trends fall within the range of natural variability or represent a drastic deviation.

Ice core data also help refine climate simulations by improving assumptions about Earth system sensitivity and by showing which factors during past warm periods led to rapid sea level rise, altered wind systems, and weakened ocean currents.

Beyond research insights, historical ice data has shaped past environmental policy. Core samples supporting trends in lead levels contributed to major international bans on leaded fuel.

Similar findings have established baselines for industrial pollutants, helping inform global treaties. With these latest samples now undergoing detailed analysis in the UK, the scientific community is poised to uncover new patterns, thresholds, and mechanisms that will either reinforce or challenge current climate models.

These cores are more than ancient ice; they are direct records of Earth's breath through time. As they are studied over the next few years, they may reshape how humanity understands not just how the planet changed in the past, but how it could change in the near future.