Mass Extinction Linked to Ancient Climate Change, New Details Reveal

Measurements of ancient climate have depended on an assumption of how to apportion the contributions of ocean temperatures and mass of ice sheets to the ratios of isotopes of oxygen preserved in sediments. A new method, based on the preferential “clumping” or bonding of isotopes, can avoid the necessity of making such assumptions, by more directly measuring temperature. Once this is done, an estimate can then be made of how much lighter oxygen isotope was tied up in ice sheets. The extensive ice thus estimated is thought to have contributed to mass extinction, partly by lowering sea levels and hence limiting the amount of life-breeding shallow waters on continental shelves.
Source: Science Daily / California Institute of Technology