Release Date: October 19, 2009 Much has been claimed in regards to the present warming being a 'natural' warming. That is, after they had claimed for a couple of decaded that no warming was occuring. However, this PNAS study indicates that is not the case. The present warming is unlike any other in recent history, 200,000 years. Arctic Sediments Show That 20th Century Warming Is Unlike Natural Variation - UB NewsCenter Buffalo, N.Y. 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 published today. 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."