Ancient ice from Antarctica, obtained as part of the Beyond EPICA – Oldest Ice project, contains unique climate records spanning at least the last 1.2 million years. The British Antarctic Survey (BAS) team in Cambridge, together with colleagues from across Europe, has successfully analysed 190 metres of ice from the bottom of a 2,800-metre-long ice core.
The ice cores were recovered over several years from Little Dome C in East Antarctica for an ambitious project that began over a decade ago. The analysis of the chemical composition of the ice is intended to reveal past climate and environmental conditions and is considered the gold standard by scientists. This is because it provides a continuous record of past climates using robust chemical markers.
A team of 30 researchers, engineers and experts from BAS and European research institutes spent seven weeks continuously melting each section of the valuable ice core.
The researchers confirmed that they had obtained a complete record of past climate and atmospheric composition for at least 1.2 million years. The melting process revealed an uninterrupted sequence of climate cycles, providing the oldest continuous ice core ever obtained.
The resulting data is now undergoing comprehensive analysis in laboratories across Europe, including at BAS, to uncover secrets about the Earth’s climate evolution and greenhouse gas concentrations.
The European Commission-funded project ‘Beyond EPICA – Oldest Ice’ brings together researchers from ten European countries and twelve institutions. The aim of the project is to reconstruct up to 1.2 million years of the Earth’s climate history, significantly extending the current oldest ice core record of 800,000 years, which has been the benchmark for the last 20 years.
Dr Liz Thomas, head of the British Antarctic Survey’s ice core team, said: ˶This is a historic moment – we now have the longest continuous record of ice cores, providing us with a blueprint for our Earth’s climate. It has been a tremendous achievement to get to the point where we have now melted 190 metres of the oldest parts of the ice core. The true age of the ice will only be determined once all the data has been collated, but our best estimates suggest it is over 1.2 million years old. It has been an enormous pressure, an enormous team effort and an enormous reward to get to this point and through to the end˝.
The analysis of this melted ice is important. We all want to understand why our planet’s climate cycle shifted from 41,000 to 100,000 years about a million years ago. By extending the ice core records beyond this turning point, we hope to improve predictions of how the Earth’s climate might respond to future increases in greenhouse gases.
The British Antarctic Survey’s ice core team specialises in continuous flow analysis – a state-of-the-art technique that involves melting ice core sections ultra-slowly to simultaneously measure a range of chemical elements, particles and isotope data. Thanks to their expertise and the support of UK Research and Innovation (UKRI), the team has been selected to lead the contamination analysis of the oldest Antarctic ice core ever recovered. Other European laboratories will analyse the ice cores for greenhouse gases (CO₂ and methane).
Until now, scientists have relied on marine sediment cores to study climate cycles over millions of years. These marine records play an important role in dating ice age and interglacial cycles. What is special about ice cores is that the bubbles trapped inside them record atmospheric conditions, changes in greenhouse gas concentrations and chemical evidence of temperatures at the time of their deposition.
Heiner Kubny, PolarJournal
Press release British Antarctic Survey