U.N. climate experts reportedly fear global warming might cause the Earth's temperature to rise far higher than now predicted.
The Geneva-based Intergovernmental Panel on Climate Change says scientists are unable to reliably predict how quickly the atmosphere will warm as carbon dioxide levels increase, The Guardian reported Tuesday.
The report will be presented to national governments in April. IPCC members meet in June to produce a final version of the report that's to be made public next year.
The IPCC previously estimated a doubling of carbon dioxide would increase average global temperature by between 2.7 degrees and 8.1 degrees Fahrenheit. Since then, some computer models have predicted increases as high as 20 F.
Sources say the draft now assumes a doubling of carbon dioxide would result in a temperature rise between at least 3.6 F and 8.1 F, with greater increases possible.
Dave Stainforth, an Oxford University climate modeler, told The Guardian: "This is something of a hot topic, but it comes down to what you think is a small chance. Even if there's just a half percent chance of destruction of society, I would class that as a very big risk."
Copyright 2006 by United Press International
Explore further: Permafrost: hiding a climate time bomb?