Just off the coast of Santa Barbara, scientists discovered further evidence that a deadly comet may have bombarded North America 12,900 years ago.

Earlier this year, UCSB professor emeritus James Kennett and nine other researchers released a report suggesting that a major cosmic event had occurred thousands of years ago, wiping out entire species and cooling the climate. The findings were based on the discovery of microscopic diamonds in North American soil that can only be produced under the intense circumstances of a colossal explosion.

Recently, James Kennett and his son, Douglas Kennett, an associate professor of anthropology at the University of Oregon, led a team of 15 researchers to study the Younger Dryas Boundary on Santa Rosa Island for additional evidence. Within this sedimentary layer, the scientists once again discovered the nanodiamonds that suggest a major cosmic impact.

“The type of diamond we have found, lonsdaleite, is a shock-synthesized mineral defined by its hexagonal crystalline structure,” Douglas Kennett said in a press release. “It forms under very high temperatures and pressures consistent with a cosmic impact. These diamonds have only been found thus far in meteorites and impact craters on Earth and appear to be the strongest indicator yet of a significant cosmic impact.”

James Kennett said the large quantity of soot found among the diamonds indicates the presence of large-scale wildfires during the time of the impact. Kennett also said numerous animals were quickly driven into extinction around the time the crash was predicted to occur. For example, the pygmy mammoth, which used to exist on the island, was not found to have a fossil record after the phenomenon.

Additionally, James Kennett said that when the comet hit approximately 12,900 years ago, Earth was in a very critical time of its history. According to Kennett, the abrupt climate change and significant loss of DNA diversity in the organisms present in North America indicate a large die-off. Approximately 35 mammal species, 19 bird species and the human culture in North America known as the Clovis became extinct at this time. Kennett refers to this sordid era in the Earth’s past as “12.9.”

“Humans were around: the Clovis people,” Kennett said. “There seems to be a gap [in human populations], suggesting a population crash. Whatever happened at 12.9 knocked out the Clovis culture.”

According to James Kennett, the impact was most likely from a comet, since no shock quartz – a common compound found in meteorites – or large impact crater was found in the layer of earth. Because comets are rich in carbon, water and ammonia, Kennett said comets heading for Earth break apart in the atmosphere and cause a “shotgun effect,” covering a wide expanse of the Earth and affecting the overall climate of the planet.

“The distribution of materials is wide, maybe even in Western Europe,” Kennett said. “[A comet] would have a shotgun effect, creating cometary clouds that would cover a wider area. There would be multiple pieces, [but not a] crater.”

Moreover, James Kennett said that there was an abrupt cooling at this time consistent with cosmic impact.

“We speculate that the clouds from the impact led to a large ocean change,” Kennett said. “[It caused] a cooling that reinforces cooling … a positive feedback loop that lasted over 1,000 years, changed ocean circulation and carried the cooling over long term. The reason was tied to a plumbing change in North America.”

The father-son team’s research has spanned one and a half years thus far. Up next for the pair is a trip to Greenland to study the same layer, where they predict they will find more hexagonal diamonds.