July 28, 2021

On the hunt for the oldest ice on Earth | Science

On the hunt for the oldest ice on Earth | Science

At the beginning of the last decade, a team of European researchers found a time machine in Antarctica. After years of work they had extracted an ice column more than three kilometers long in which, layer by layer, the climate of the Earth was written from now until 800,000 years ago, the most complete continuous record of this type of which there is constancy. Trapped in the millenary ice were bubbles of oxygen and carbon dioxide that allowed us to estimate the temperature and composition of the atmosphere over time, essential data to understand what the effects of climate change will be on the antartida, where 90% of all the ice water on the planet is concentrated.

The same team now wants to travel until 1.5 million years ago and knows how to get it. Researchers from Germany, Italy and France today presented a project funded by the European Union to drill a continuous ice column of 2,700 meters in a remote place called Small Dome C, located in an area of ​​East Antarctica where the average temperature a throughout the year it is 50 degrees below zero.

"The site is a small hill about 400 meters high where we have detected a continuous record of ice that reaches the rock and has not melted by its base," he explains. Matter Olaf Eisen, project coordinator, called Beyond EPICA. "It will take us two years to prepare the camp. We hope to start drilling in 2021 and continue each Antarctic summer [noviembre a enero] until 2025, "explains the researcher at the Alfred Wegener Institute in Germany. The different fragments of the column will be transported first to the Concordia base, a Franco-Italian scientific enclave located in Dome C of the Antarctic plateau, the immense 1000-kilometer-diameter ice shell surrounding the South Pole. Later they will be transferred to several European research centers where a detailed analysis of the treasured gases in the samples will be made. The study will probably extend until the beginning of the next decade, says Eisen. The project, which involves 10 European countries is in the process of being approved by the European Union will be endowed with about 11 million euros, says the glaciologist.

The chosen place is about 40 kilometers from where the first column of 800,000 years was taken during the EPICA project. "There are other places where the ice is even older, the problem is that we know that the ice at the base, the oldest part, has melted due to geothermal activity," explains the glaciologist.

The team has spent the last three Antarctic summers cruising the ice on board caterpillar vehicles towing a radar that indicates if there is melting at the base. After traveling about 5,000 kilometers and analyzing several points, the Small Dome C is the one with the oldest intact layer of ice. There are other places in Antarctica where the winds have swept the snow exposing even more ancient blue ice. US teams have managed to detect layers from about 2.7 million years ago, the problem is that in these cases they are isolated records, which makes it impossible to use them to reconstruct the complete evolution of the climate.

The project involves 10 countries and will be endowed with about 11 million euros

"Thanks to the bubbles of oxygen and carbon dioxide trapped in the ice we can know the temperature and the concentration of CO₂ during the last million and a half years, a unique record that also allows us to know other characteristics such as the dust content or the level of precipitation, "explains Eisen.

These columns of ice are essential to better understand cycles of glaciation and if high levels of carbon dioxide, a greenhouse gas whose concentration in the atmosphere has dramatically increased by human activity, they played an important role. This information will serve to better understand the future of the great masses of Antarctic ice beyond 2100, when higher concentrations of greenhouse gases are expected due to human activity. Especially important is to understand what factors mark the change of natural cycles and if the signs of melting and heating already detected in the continent are irreversible. "There is no other point on the planet where all this information can be extracted from the ice," says Eisen.


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