Oldest Antarctic ice core reveals climate history

Secrets of the Earth’s past climate locked in a three-kilometre long Antarctic ice core are revealed this week in the journal Nature. The core from Dome C, high on East Antarctica’s plateau, contains snowfall from the last 740,000 years and is by far the oldest continuous climate record obtained from ice cores so far.

The ice has been collected in an eight year project by scientists and engineers from 10 European countries. Analysis of ice cores shows how temperature changed in the past, but also how the concentrations of gases and particles in the atmosphere varied.

The first results confirm that over the last 740,000 years the Earth experienced eight ice ages, when Earth’s climate was much colder than today, and eight warmer periods (interglacials). In the last 400,000 years the warm periods have had a temperature similar to that of today. Before that time they were less warm, but lasted longer.

By comparing the pattern of this past climate with global environmental conditions today the scientists conclude that, without human influence, we could expect the present warm period to last at least another 15 000 years.

The next step in the research is to extract air from tiny bubbles in the ice, and to find out how the atmosphere’s composition has varied. Preliminary analyses show that the present carbon dioxide concentration is the highest level seen in the last half a million years. By understanding what drove past changes in climate, the scientists expect to improve predictions about future climate.

The Dome C drilling is part of the ‘European Project for Ice Coring in Antarctica’ (EPICA). The team at Dome C endured temperatures of minus 40ºC at the remote drilling site thousands of kilometres from the nearest research station. The consortium will continue to drill at the site from December 2004, and hopes to reach the rocks at the base of the ice sheet. There are just 100 metres still to drill, and if all goes well, the team will reach ice over 900,000 years old at the base.

Issued on behalf of the EPICA Steering Committee, The European Union, and the European Science Foundation.

Further background information:
The 'EPICA' project (European Project for Ice Coring in Antarctica) is run by a consortium of ten European countries: Belgium, Denmark, Germany, Great Britain, France, Italy, Norway, Sweden and Switzerland. EPICA is coordinated through the European Science Foundation (ESF) and is funded by the participating countries together with the European Union. The goal of EPICA is to drill two ice cores through the inland ice of the Antarctic down to the rock surface.

Apart from the drilling at Dome C (75° 06’S, 123° 21’E), there is a second drill hole at the 'Kohnen'- Station in Dronning Maud Land (75°00'S, 00°04'O) that has currently reached 2565 m depth. The German partner in the EPICA project is the Alfred Wegener Institute for Polar and Marine Research (AWI) in Bremerhaven. It has responsibility for the drilling in Dronning Maud Land. In addition, Prof Heinz Miller, acting director at the AWI, manages overall EPICA project coordination. EPICA is one of the core projects within the AWI research framework ’Marine, Coastal and Polar Systems’ (MARCOPOLI). MARCOPOLI is part of the research area "Erde und Umwelt" ('Earth and Environment') of the "Helmholtzgemeinschaft".

Ice cores are ice cylinders 10 cm in diameter, that are gradually retrieved in segments of up to 3 m length during the drilling process. Ultimately, this ice originates from snowflakes falling over hundreds of thousands of years. In the process of falling, flakes collect aerosol particles from the air. Over time, snowflakes are transformed into ice crystals, encapsulating the air between them, together with minute particles, in small bubbles.

Analyses of the chemical composition, as well as the physical properties of the ice and the enclosed air allow scientists to study the relationship between atmospheric processes and climatic changes of the past. In the case of Dome C, the frosty climate archive dates back 740,000 years. In this work, special emphasis is placed on the effects of carbon dioxide, methane and other components. The results are used to control and further develop mathematical models, which serve in the prediction of future climate conditions.

Field research in the Antarctic imposes significant scientific and logistic challenges on scientists and technicians. The locations where ice cores are drilled within the framework of 'EPICA" are some of the most remote and inhospitable places on earth.

Bremerhaven, June 7th, 2004