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05 June 2019

In Search of the Oldest Ice in the World

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Antarctica holds about 90% of all the ice in the world. If it were all to melt, sea levels would rise by about 60 metres. It is the place on the planet where scientists find it most difficult to venture how the ice sheets will behave as the world warm. It is an area where the ocean collides with an enormous amount of fresh water ice, with very strong winds, and a powerful marine current, the so-called Antarctic Circumpolar Current, spinning frantically from west to east.

Its eastern part is the most isolated, cold, inhospitable and lifeless area of ​​Antarctica, in other words, of the Earth. It has never been visited by intrepid tourists. And yet it is precisely here, despite the desolation and bitter cold, that a group of European scientists are eager to reach.

Ice column extraction near Concordia station. Credit: Thibaut Vergoz, French Polar Institute, CNRS: Thibaut Vergoz, Instituto Polar Francés, CNRS

The project Beyond EPICA Oldest Ice (European Project for Ice Coring in Antarctica) is a mission to drill Antarctic ice organised by ten European countries —which doesn’t include Spain. The objective is to extract a column of continuous ice core to a depth of about three kilometres, almost to the base of the rock on which the water began to freeze. Once extracted, it will be sent to various laboratories to analyse the thousands of air bubbles that were trapped at the time it was formed.

A time machine

These bubbles contain the composition of the atmosphere at successive times in Earth’s climate history, and scientists are especially interested in two parameters: the concentrations of carbon dioxide and methane, the most important greenhouse gases. Since the deeper the ice lies, the older it is, Beyond Epica aims to extract ice as old as a million and a half years. These columns are often compared to real fossils or time machines, but regardless of the success of the metaphor, if all goes well, it would be the oldest ice in the world.

“In the early 2000s, we recovered a core of Antarctic ice that gave us a climate record of the past 800,000 years. We learned a lot about the critical periods of changes between warm periods and ice ages. Now we want to go back even further than a million years, when the climate of the planet, which alternated between cold glacial conditions and warmer interludes, went from being dominated by a pattern of 41,000 years to a cycle of 100,000 years,” explains Robert Mulvaney, glaciologist at the British Antarctic Survey and part of Beyond Epica. It is a question of understanding what determined the change in the terrestrial glacial cycles and whether the increase in carbon dioxide levels played an important role, together with other factors such as changes in the rotational inclination of the Earth, to try to predict better what the rise in temperature will bring.

Setting up one of the radar systems to measure the vertical deformation of the ice sheet. Credit: Robert Mulvaney, BAS

For the past three years, Mulvaney and his colleagues have been searching for the ideal place to find this more-than-one-million-year-old ice in good condition and able to be extracted safely. To achieve this, they used radar in low altitude flights and extracted samples at depths of about 400 metres. Their results allowed them to understand the characteristics of the deepest and, therefore, the oldest ice sheets, until one of them turned out to be a winning place to drill: a place they named Little Dome C.

The white world

Little Dome C is located a couple of hours by snowmobile —about 50 kilometres— from the Concordia Antarctic research station, operated by the French and Italians, in the so-called Wilkes Land region, at an altitude of 3,233 metres above sea level. Scientists who work there don’t usually see raindrops fall: the average annual temperature is 54.5 degrees below zero, rarely exceeds -25°C, and in winter the mercury can easily drop to a bone-chilling minus 80 degrees. Little Dome C would be the antithesis of hell.

This place has several characteristics that make it unique for this mission: it has ice of at least 1.5 million years old, offers good resolution even in its oldest parts, but above all, it is not melting at the base, the oldest area. One of the many problems with extracting such deep samples is that the heat flow coming from the Earth’s interior, added to the insulating effect of the thick layer of overlying ice, ends up melting the ice.

Little Domce C drill site. Credit: Luca Vittuari, PNRA

While the European Union has yet to approve the full funding for this project, the drilling campaign begins this month of June. A team of experts coordinated by glaciologist Carlo Barbante, from the University of Venice, will set up a camp at Little Dome C where scientists will live in cargo containers. First they will have to prepare the camp, which will take them about two years to complete, in order to start drilling from 2021 to 2025 during the Antarctic summer months, between November and January.

“We know that our climate is changing. What we don’t yet fully understand is how the future climate will respond to the growing greenhouse gases in our atmosphere beyond 2100 and whether there will be tipping points in the system that we are not yet aware of. It would be helpful if we could understand what happens when the length of natural climate cycles changes. We can only get this information from the Antarctic ice sheet. Embarking on this mission is tremendously exciting,” concludes Olaf Eisen, coordinator of the project and glaciologist at the Alfred Wegener Institute for Polar and Marine Research.

Eugenia Angulo


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