As Earth was coming out of the last Ice Age roughly 13,000 years ago, temperatures suddenly plummeted again for a further 1,200 years. It also left the human population struggling to exist, with some estimates suggesting the population dropped to below 10,000 globally at the end of the Ice Age.
That brief period is likely to have contributed to the extinction of some of the planet’s most impressive animals, including the woolly mammoth, the sabre-toothed cats and the giant sloth – which stood at a staggering 20 feet tall.
Researchers know this from analysing sediments in Canada, which show glaciers melting before freezing all over again.
The event is known as the Younger Dryas event, and it had been thought the temperature plunge was caused by a meteor hitting Earth.
However, new research shows the mini Ice Age, where temperatures dropped by an average of three degrees Celsius, was actually caused by volcanic eruptions, sparking a miniature volcanic winter – where ash and debris fills the skies, making it more difficult for sunlight to reach the surface.
A team of scientists based in the US have analysed layers of sediment in Halls Cave, Texas, which have shown to be consistent with volcanic eruptions.
Michael Waters, director of The Center for The Study of the First Americans and Distinguished Professor at Texas A&M University, said: “It is an exceptional record that offers a unique opportunity for interdisciplinary cooperation to investigate a number of important research questions.
“One big question was, did an extraterrestrial impact occur near the end of the last ice age, about 13,000 years ago as the ice sheets covering Canada were melting, and cause an abrupt cooling that thrust the northern hemisphere back into the ice age for an extra 1,200 years?
“This period of rapid cooling coincides with the extinction of a number of species, including camels and horses, and the appearance of the Clovis archaeological tradition.”
Alan Brandon, professor of geosciences at the University of Houston and head of the research team, said: “The trigger for this cooling event didn’t come from space.
“Prior geochemical evidence for a large meteor exploding in the atmosphere instead reflects a period of major volcanic eruptions. I was sceptical.
“We took every avenue we could to come up with an alternative explanation, or even avoid, this conclusion. A volcanic eruption had been considered one possible explanation but was generally dismissed because there was no associated geochemical fingerprint.”
Analysis also revealed the planet was on the tipping point of a rapid cooling period, and the volcano eruptions pushed it over the edge.
Co-author Steven Forman, professor of geosciences at Baylor said: “So a sole volcanic eruptive cause is an important initiating factor, but other Earth system changes, such as cooling of the oceans and more snow cover were needed to sustain this colder period.”