The theory that the minute amounts of CO2 in the atmosphere have an outsize influence on climate was dealt another serious blow by the publication in a peer-reviewed journal of a study showing that the climate about 460 million years ago was similar to that of today, even though atmospheric carbon dioxide was at least 4 or 5 times the level of today. From Watt's Up with That?:

An international team of scientists including Mark Williams and Jan Zalasiewicz of the Geology Department of the University of Leicester, and led by Dr. Thijs Vandenbroucke, formerly of Leicester and now at the University of Lille 1 (France), has reconstructed the Earth's climate belts of the late Ordovician Period, between 460 and 445 million years ago.

The findings have been published online in the Proceedings of the National Academy of Sciences of the USA - and show that these ancient climate belts were surprisingly like those of the present.