Arctic sediments show 20th-century warming is an unnatural variation

By Staff Writers, Buffalo NY (SPX) Oct 29, 2009 The possibility that climate change might simply be a natural variation like others that have occurred throughout geologic time is dimming, according to evidence in a Proceedings of the National Academy of Sciences paper. The research reveals that sediments retrieved by University at Buffalo geologists from a remote Arctic lake are unlike those seen during previous warming episodes. The UB researchers and their international colleagues were able to pinpoint that dramatic changes began occurring in unprecedented ways after the midpoint of the twentieth century. “The sediments from the mid-20th century were not all that different from previous warming intervals,” said Jason P. Briner, PhD, assistant professor of geology in the UB College of Arts and Sciences. “But after that things really changed. And the change is unprecedented.” … “There are periods of time reflected in this sediment core that demonstrate that the climate was as warm as today,” said Briner, “but that was due to natural causes, having to do with well-understood patterns of the Earth’s orbit around the sun. The whole ecosystem has now shifted and the ecosystem we see during just the last few decades is different from those seen during any of the past warm intervals.” Yarrow Axford, a research associate at the University of Colorado, and the paper’s lead author, noted: “The 20th century is the only period during the past 200 millennia in which aquatic indicators reflect increased warming, despite the declining effect of slow changes in the tilt of the Earth’s axis which, under natural conditions, would lead to climatic cooling.” …

Arctic Sediments Show 20th Century Warming Is An Unnatural Variation