The microfossil that indicates high amounts of ancient CO2 in this image, Photo by Shuhai Xiao at Virginia Polytechnic Institute

Washington - Sep 19, 2003

Billions of years ago, there was a lot more greenhouse gas than today, and that was a good thing – else the Earth might be an icy ball. How much greenhouse gas was there in the ancient atmosphere? A 1993 model by Jim Kasting of Pennsylvania State University estimates that carbon dioxide (CO2) levels in the Earth's early atmosphere must have been 10 times to as much as 10,000 times today's level, in order to compensate for the young (and fainter) sun.

Now, a measurement of the fossil record using a new instrument has confirmed a portion of the model. Atmospheric CO2 level 1.4 billion years ago was at least ten to 200 times greater than today, according to the new research.

The findings are reported in the September 18, 2003, issue of Nature by Alan Jay Kaufman of the geology department at the University of Maryland and Shuhai Xiao of the geosciences department at Virginia Tech ("High CO2 levels in the Proterozoic atmosphere estimated from analyses of individual microfossils").

The rest is here: http://www.spacedaily.com/news/early-earth-03h.html