Research by the University of Birmingham has provided evidence that a warm atmosphere rich in carbon dioxide was present in an ancient ice age.  This could only have happened if the planet was nearly all covered in ice and snow. 

Scientists from the University’s School of Geography, Earth and Environmental Sciences, say that, whereas today, we associate more greenhouse gases with a warm world, in a very severe ice age, even plenty of greenhouse gas cannot stop the world being covered in reflective ice and snow.

This type of glaciation could occur again in the future if the Earth’s atmosphere reflected too much solar radiation - this process could be triggered by a nuclear war creating a dusty mantle around the Earth.  The same applies if we were not careful with a suggested technological fix for global warming and launched tiny particles (aerosols) of sulphate into the atmosphere.  Such aerosols arise both from industrial pollution and from volcanic activity, and even in trace quantities are known to cause cooling. 

Dr Ian Fairchild, lead investigator, says, ‘We came up with an independent test of a theory that the Earth, like a baked Alaska pudding, was once hot on the outside, surrounding a cold, icy surface.  It happened naturally in the past, but the wrong use of technology could make it happen again’

The breakthrough discovery was made by studying limestones that were deposited around 630 million years ago in salt lakes next to an ice sheet.  The scientists measured the relative amounts of heavier and lighter forms of oxygen and sulphur and found anomalies that could only be accounted for by a very unusual composition of the atmosphere at the time.  Appropriately, the place where the samples were collected is in Svalbard in the Arctic Ocean and is today covered in ice and snow, but 630 million years ago, nearly the entire planet would have been ice-bound.


Notes to Editors

This paper was written with Huiming Bao, Louisiana State University, Peter Wynn, Lancaster University, Christoph Spoetl, University of Innsbruck. 

The paper will appear in Science on Friday 2nd January 2009.  Please visit:

For further information

Kate Chapple, Press Officer, University of Birmingham, tel 0121 414 2772 or 07789 921164.