Mukul Sharma

Evidence Found for Planet-Cooling Asteroid (Nature)

Nature points to a new study co-authored by Dartmouth’s Mukul Sharma, a professor in the Department of Earth Sciences, that links the impact of a comet or meteor striking the Earth to the dramatic global climate change that occurred 12,900 years ago.

“I’d say there’s evidence of an impact happening, for sure,” Sharma tells Nature. The researchers recovered minerals in Pennsylvania similar to those found in Quebec, where Sharma and his colleagues believe the impact took place, Nature reports.

Read the full story, published 9/2/13 by Nature.

Study Links Prehistoric Climate Shift, Cosmic Impact

For the first time, a dramatic climate shift that has long fascinated scientists has been linked to the impact in Quebec of an asteroid or comet, Dartmouth researchers and their colleagues report in a new study funded by the National Science Foundation.

The event took place about 12,900 years ago, at the beginning of the Younger Dryas period, and marks an abrupt global change to a colder, dryer climate, with far-reaching effects on both animals and humans, the scientists say. In North America the big animals, including mastodons, camels, giant ground sloths, and saber-toothed cats, all vanished. Their human hunters, known to archaeologists as the Clovis people, set aside their heavy-duty spears and turned to a hunter-gatherer subsistence diet of roots, berries, and smaller game.

Dartmouth Researchers Say a Comet Killed the Dinosaurs

JOSEPH BLUMBERG

In a geological moment about 66 million years ago, something killed off almost all the dinosaurs and some 70 percent of all other species living on Earth. Only those dinosaurs related to birds appear to have survived. Most scientists agree that the culprit in this extinction was extraterrestrial, and the prevailing opinion has been that the party crasher was an asteroid.

Not so, say two Dartmouth researchers. Professors Jason Moore and Mukul Sharma of the Department of Earth Sciences favor another explanation, asserting that a high-velocity comet led to the demise of the dinosaurs.
Recently, asteroids have been in the headlines. On February 15, 2013, an asteroid exploded in the skies over Siberia. Later that day, another swept past the Earth in what some regard as a close call—just 17,000 miles away.