Ice cores reveal fluctuations in the Earth's greenhouse gases

The ice core boring at Dome C in Antarctica shows that the curves for the temperature and the greenhouse gases carbon dioxide and methane follow each other over the past... Click here for more information.

Ice cores from Antarctica show both the lowest atmospheric content of CO2 (carbon dioxide) and fast changes in the content of CH4 (methane) measured over the past 800,000 years. Knowledge about the relationship between greenhouse gases and the temperature in the Earth’s climate history will help scientists develop models of future climate changes.

The results obtaines in the framework of the European Project for Ice Coring in Antarctica (EPICA) run by a consortium of 10 European Nations among them the Niels Bohr Institute at University of Copenhagen are being published in two articles in the respected scientific journal Nature.

An ice core drilled through the three-kilometre-thick ice cap at the EPICA Dome C Station in the middle of Antarctica reveal the climate 800,000 years back in time – through eight glacial periods and eight interglacial periods. The glacial periods last 100,000 years on average, and the warm interglacial periods – such as the one we are now in – last an average of 10,000 years.

The European EPICA bore project at Dome C in the middle of Antarctica. Click here for more information.

The ice is formed by snow falling year after year and which, with time, is compressed to form a thick ice cap. The ice contains atmospheric air, and the annual layers provide information about the climate in the years in which the snow fell. The mix of water isotopes in the ice reveals the temperature, and analyses of the entrapped air show the atmospheric content of gases such as carbon dioxide and methane.

Extremely low CO2 content