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UDaily: Cosmic crash in Canada may have caused global climate shift 12,900 years ago

UDaily: Cosmic crash in Canada may have caused global climate shift 12,900 years ago

A dramatic global climate shift may be linked to the impact of an asteroid or comet in Quebec, according to researchers from the University of Delaware, Dartmouth College and Elizabeth City State University. The findings appear in the Sept. 2 online Early Edition of the Proceedings of the National Academy of Sciences (PNAS).

According to the scientists’ hypothesis, the impact occurred about 12,900 years ago at the beginning of the Younger Dryas period and marked an abrupt global change to a colder, drier climate with far-reaching effects on both animals and humans. In North America, many big animals vanished, including mastodons, camels, giant ground sloths and saber-toothed cats.

It is not disputed that these powerful environmental changes occurred, but there has long been controversy over their cause. The classic view of the Younger Dryas cooling interlude has been that an ice dam in the North American ice sheet ruptured, releasing a massive quantity of freshwater into the Atlantic Ocean. The sudden influx is thought to have shut down the ocean currents that move tropical water northward, resulting in the cold, dry climate of the Younger Dryas.