Scientists have uncovered compelling new evidence from the ocean floor supporting the controversial theory that a disintegrating comet triggered a dramatic global cooling event 12,800 years ago.
The findings, reported by University of South Carolina scientists, involve the discovery of several examples of direct evidence that Earth experienced a series of impacts from a disintegrating comet 12,800 years ago, which caused a period of cooler global temperatures lasting more than a millennium.
Although no direct evidence of the proposed ancient comet was found during the study effort, the researchers believe their findings offer strong geochemical support for a theoretical series of impacts, or more likely, an airburst event, as the cause of a brief and unexplained reversal in warming at the end of the last ice age.
The results offer strong support for the hypothesis “that the Earth collided with a large comet about 12,800 years ago,” study co-author, Dr. Vladimir Tselmovic, said. “The amount of comet dust in the atmosphere was enough to cause a short-term ‘impact winter,’ followed by a 1,400-year cooling period.”
Previous attempts to explain the 1,200-plus years of cooling that began unexpectedly in the middle of an overall global warming trend, known as the Younger Dryas, have resisted the inclusion of a cometary impact. Instead, most models account for the 10-degree Celsius drop through an increase in cold glacial meltwater that flooded the northern Atlantic Ocean. According to those theories, this meltwater runoff significantly weakened currents responsible for transporting warmer tropical water north.
To locate more concrete evidence for the comet impact hypothesis, study leader Dr. Christopher Moore and colleagues reexamined deep ocean floor core samples that include sediments confirmed by radiocarbon dating as being from this time period. Based on the best theoretical impact sites, the team used cores taken from Baffin Bay near Greenland.
To search for clues of comet impacts in the samples, the team employed multiple tools and techniques. According to the team’s statement, they employed scanning electron microscopy, single-particle inductively coupled plasma time-of-flight mass spectrometry, energy-dispersive spectroscopy, and laser ablation inductively coupled plasma mass spectrometry.
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