The deep Antarctic drill that pulled up air from a world long before humans. Image credit – Gemini
Deep under East Antarctica, scientists are drilling into one of the oldest frozen records in the world. But the ice isn’t the only thing they seek. The air bubbles locked inside it hold many secrets. The Beyond EPICA project aims to retrieve continuous Antarctic ice cores dating back as early as 1.5 million years ago. This mission is based on the assumption that the ice may carry traces of changes in the composition of Earth’s atmosphere even before humans walked the planet.According to the British Antarctic Survey (BAS), the drilling operation started in 2021 following years of radar surveys, ice flow modelling, and extensive field research showing Little Dome C was one of the few places where researchers would find some of the oldest ice on the planet.Why scientists are chasing ancient Antarctic iceThe reason scientists are after ancient ice is simple – it is rich with information beyond its frozen state. For instance, the air bubbles contained in each layer hold samples of ancient air, including gases such as CO2 and methane. These gases enable the direct study of past atmospheres without relying solely on indirect evidence.Nature’s paleoclimate topic states that the Antarctic ice cores are essential sources for understanding the history of Earth’s climate system. The trapped gases help reveal changes in temperature and greenhouse gases.BAS describes in its project material that this is one of the few ways we can directly sample ancient atmospheres. This way, the ice core serves not just as a geological sample but also as an archive of the Earth’s climate systems through time. The significance of the age objective is that current ice cores can already trace back the climatic record to about 800,000 years ago. The Beyond EPICA project seeks to break this boundary.Legacy of the EPICA recordThe current drilling project follows a previous initiative called the EPICA Dome C ice core project. A groundbreaking paper in Nature in 2004 documented the ice record, which was then estimated to be about 740,000 years old, and later revised to around 800,000 years old. This previous core revolutionised the field of climatology by establishing the correlation between greenhouse gases and the cycles of the ice ages. Going beyond EPICA aims to probe even further back in time.In particular, scientists are looking for clues about an era called the Mid-Pleistocene Transition, in which the cycle of ice ages underwent significant changes. There is still no consensus among experts about what caused this shift in timing. And the ancient ice from Antarctica could provide the explanation.
The Antarctic ice core holds a 1.2 million-year climate archive.
Selecting sites for drillingUnlike many scientific endeavours, drilling ice cores is not left to chance. Researchers rely on techniques like radar imagery, geological maps, and models of ice flow to predict areas with the potential to hold very ancient layers. As explained by BAS, the main reason for choosing Little Dome C was the assumption that the ice here would be old, undisturbed by melting, and stable.At least this is how the news release described the recently discovered sequence as the oldest continuous ice-core record ever recovered. It noted that scientists managed to obtain data spanning more than 1.2 million years from the location. This is important since fragmented and discontinuous layers are hard to read. Consistent layering enables scientists to compare levels of greenhouse gases, snow, and climatic shifts on a timescale measured in hundreds of thousands of years.Why do bubbles matter so much?Perhaps the most astonishing characteristic about the ice core is its unseen one. Air bubbles trapped in the ice represent actual samples of the ancient atmosphere. Scientists can precisely measure the concentrations of CO2 and methane found in these bubbles. This data will give them insights into the responses of climatic systems to natural changes in the past hundreds of thousands of years.According to the CORDIS research project database for the European Union, the Beyond EPICA mission is to retrieve “the oldest ice” with such an atmospheric history. For the lay reader, the magnitude of this endeavour might be hard to fathom. At the very bottom of this core, there might be air older than all human civilisation as we know it combined.A frozen archive containing many secretsThe Beyond EPICA project is an active one, and experts emphasise that further research is required. Specialists do not know how old each layer is, nor do they know whether the ultimate record will be full enough.Nevertheless, the project already has the potential to be considered one of the most significant studies of Antarctic climates in recent years. The Beyond EPICA project transforms a distant part of East Antarctica into an archive of Earth’s atmosphere. The reason why the discovery is so valuable lies in its simplicity. Air samples from a million years ago have been stored in ice until researchers decide to extract them from their long-lasting storage.
