Comet strike may have triggered ancient warming event

New York, Oct 14 A comet struck our home planet a long time ago and it could have triggered the Paleocene-Eocene Thermal Maximum (PETM), a rapid warming event caused by an accumulation of atmospheric carbon dioxide 56 million years ago, suggests new research.

Sorting through samples of sediment from the time period, researchers discovered evidence of the strike in the form of microtektites -- tiny dark glassy spheres typically formed by extraterrestrial impacts.

"This tells us that there was an extraterrestrial impact at the time this sediment was deposited -- a space rock hit the planet," said corresponding author Morgan Schaller, Assistant Professor at Rensselaer Polytechnic Institute in New York.

"The coincidence of an impact with a major climate change is nothing short of remarkable," Schaller said.

In recent years, PETM has become a major point of interest for scientists as it is perhaps the best past analog by which to understand impacts of global climate warming today.

Even so, the cause of this warming event remains a mystery. Among the suggested drivers of the observed massive injection of carbon into the atmosphere that occurred at this time are the intrusion of flood basalts into carbon-rich marine sediments, carbon degassing from volcanos, and an extraterrestrial impact on Earth.

By studying sections of marine shelf on the Atlantic Coastal Plain associated with the Paleocene-Eocene boundary, the researchers reported in the journal Science the discovery of silicate glass spherules with distinctive morphologies and micro-craters.

Based on their features, the authors said, these glass spherules are best interpreted as terrestrial debris ejected during a meteorite impact.

"A comet impact on its own may have contributed carbon to the atmosphere, but is too small to explain the whole event and more likely acts as a trigger for additional carbon releases from other sources," Schaller said.

IANS