With carbon dioxide levels in the atmosphere set to double in the next 100 years, the icy continent could revert to how it looked about 40 million years ago, said Professor Robert Dunbar of Stanford University.

"It was warm and there were bushes and there were trees," he told some 850 delegates in the Tasmanian capital Hobart, the national AAP news agency reported.

The delegates are attending the combined meetings of the Scientific Committee on Antarctic Research and the Council of Managers of National Antarctic Programs.

Dunbar said climate experts were predicting a doubling of the levels of carbon dioxide by 2100, "but it actually looks like it's going to come sooner unfortunately".

Scientists blame greenhouse gases such as carbon dioxide, produced mainly by the burning of fossil fuels such as coal and oil, for causing rising temperatures worldwide.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.