Air bubbles tell the story of the climate

by Heiner Kubny

07/14/2026

Dr Daniel Baggenstos monitors a sublimation process in which greenhouse gases trapped in bubbles are extracted from a 50 g ice sample without the ice melting. (Photo: Mark Horstman)

As part of the Australian ‘Million Year Ice Core’ (MYIC) project, scientists are studying air bubbles that have been trapped in Antarctic ice for thousands to millions of years. This air contains greenhouse gases such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), providing a direct insight into Earth’s past atmosphere.

The ice cores come from East Antarctica, near the Casey research station. The aim of the project is to obtain ice samples containing climate data dating back more than a million years. The researchers hope this will help them solve a major mystery of climate history: around a million years ago, the cycle of ice ages changed from approximately 40,000 to 100,000 years. One theory suggests that a decline in atmospheric carbon dioxide was responsible for this change.

Ice core drilling site at Dome C North in East Antarctica. Here, researchers are extracting ice cores several kilometres long, which contain climate and atmospheric data spanning up to two million years of Earth’s history, thereby providing unique insights into past climate changes. (Photo: Joel Pedro)

Two methods are used to analyse the trapped gases. In the first method, known as sublimation, a small piece of ice is heated in a vacuum chamber. The ice turns directly into water vapour without melting, and the trapped gases are released. Their concentrations are then measured using a spectrometer.

The second method is continuous flow analysis. In this process, long ice rods are melted in a controlled manner so that the air bubbles are released in the order in which they were originally trapped. This method is particularly suitable for analysing methane and enables the rapid analysis of large quantities of ice.

After being drilled in East Antarctica, the ice cores were transported to Australia, where they are being analysed for information about past climates. (Photo: Joel Pedro)

Methane is of particular interest to researchers as it plays an important role in the climate system and its concentration in the atmosphere can change relatively rapidly. It can also be used to date ice cores and compare them with other climate data.

The research not only provides insights into the Earth’s climate history, but also helps to improve climate models and better predict future climate trends. By the end of the decade, the scientists aim to drill to a depth of around 3,000 metres and retrieve ice that is older than any ice sample studied to date.

The ice cores are kept frozen in special insulated containers during transport to Australia. (Photo: Joel Pedro)

Conclusion

The analysis of ancient air trapped in Antarctic ice cores is a significant contribution to climate research. It enables the composition of the atmosphere to be reconstructed over very long periods and provides a better understanding of the links between greenhouse gases and climate change. The results of the MYIC project could yield crucial new insights into the past and future of the Earth’s climate.

Heiner Kubny, PolarJournal