Antarctic ice cores contain air bubbles hundreds of years old

A group of scientists who have drilled into the ice in Antarctica to extract part of its core have come to understand that it contains air bubbles hundreds of years old. Scientists say their ice core data show that greenhouse gas levels were lower in the past than they are today.

A team of scientists has drilled deep into an ice sheet, 650 meters, to extract part of the Antarctic ice core.

Their tent is pitched in the isolated, hostile and uninhabited icy land of Skytrain Ice Rise in Antarctica.

By probing the icy depths of the continent, these scientists from the University of Cambridge and British Antarctica are working to understand what makes Antarctica's ice sheets so vulnerable.

They extracted large pieces about 80 cm of the ice core, which were further cut for analysis.
Scientists spent three months drilling here between 2018 and 2019.
The extracted ice cores contain air bubbles, which are being considered a direct sample of the 200-year-old atmosphere in Antarctica.

Thomas Bauska, a researcher at British Antarctic Survey, at this year's Royal Summer Science Exhibition in London, shows how an ice core sample melts and releases air bubbles.

"What I have here is an ancient ice core sample in this little cup and if you can listen to it, now with the microphone, you can hear the bubbles coming out and that's actually air being released, so what's going on get now it's probably the cleanest air you'll ever breathe," he says.

Air bubbles are released as the ice is submerged in water and as the ice melts in warmer ambient temperatures.

Bauska says their ice core data show that greenhouse gas levels were lower in the past than they are today. 

"The concentration of gases like carbon dioxide, methane, all the greenhouse gases that are causing global warming today, were much lower in the past, and what our ice core data shows is that the world we live in now there are unprecedented levels of greenhouse gases," he says.

With an average annual surface temperature of minus 26 degrees Celsius, extracting Antarctic ice cores was a physically challenging and slow process for the researchers involved.

"So the first thing you have to do is of course to drill the ice core, which in some cases can take months and sometimes the deepest cores, which are actually almost over 3 km in depth, can it takes years to drill," says Bauska.

Aircraft from British Antarctica and the British Royal Air Force were used in ice core extraction and transport in specific conditions. 

Some ice core samples were kept in tents on the Skytrain Ice Rise with sub-zero temperatures that were optimal for long-term storage.

The ice core samples gave scientists historical insight into patterns of massive ice loss spanning thousands of years.

Through the exhibition, the research team hopes to raise awareness of the changes taking place in Antarctica, highlighting that significant ice loss there could have harmful implications for people around the world.