University of Oregon scientists say prehistoric global warming may have saved the Earth from greenhouse sterilization.

The global warming from massive atmospheric pollution involving carbon dioxide and methane might have caused "mass kills" of wildlife, according to the study to be presented during the Geological Society of America's annual meeting Oct. 16-19 in Salt Lake City, Utah.

The research by Gregory Retallack, professor of geologic sciences, involved a worldwide compilation of thousands of exceptionally well preserved fossils of various life forms believed to have been preserved in environments unusually low in oxygen, highly saline, very cold or extremely dry.

What was not suspected until the new compilation was the global distribution of other fossil deposits of the same ages.

"Lowered levels of oxygen can kill fish and other creatures in marginally aerated environments, and also preserve their carcasses from dismemberment and decay," said Retallack. He said data from carbon anomalies and microscopic leaf pores indicate some "killer greenhouses" produced intolerable levels of more than 10 times the modern level of atmospheric carbon dioxide.

He said the widespread death and burial of animals and their carbon created fossil bonanzas and may have saved the planet from heat sterilization.

Copyright 2005 by United Press International