Earth cooled rapidly 13,000 years ago and the reason for this is a series of volcanic eruptions that have caused a drop in global average temperature of 3 ° C, according to a study.
Previously, a meteor impact was believed to be responsible, but a new study found that this was incorrect.
Previous theories were based on geological findings that had been mistakenly attributed to rocks that landed from space.
However, a new analysis of the rock sediments shows that they instead came from the depths of the Earth and were projected to the surface through violent eruptions.
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Earth cooled rapidly 13,000 years ago and the reason for this is a series of volcanic eruptions that caused a drop in global average temperature of 3 ° C, according to a study (Stock)
The cooling period of the world is known as Younger Dryas and is associated with the first human colonists and the extinction of the woolly mammoth.
Co-author of Professor Alan Brandon, of the University of Houston, said: ‘This work shows that the geochemical signature associated with the cooling event is not unique but occurred four times between 9,000 and 15,000 years ago.
‘Therefore, the trigger for this cooling event did not come from space.
“Previous geochemical evidence of a large meteor exploding into the atmosphere instead reflects a period of major volcanic eruptions.”
Volcanic eruptions diffuse particles into the atmosphere, which reflect the thermal energy of sunlight away from the surface.
A “global cooling” period can follow a volcanic explosion for one to five years, depending on the period and scale of the eruption.
Co-author Professor Steven Forman, of Baylor University in the United States, said: “The Younger Dryas, which occurred some 13,000 years ago, stopped distinct heating at the end of the last ice age.
“Earth’s climate may have been at a turning point in the Younger Dryas, probably from the discharge of the ice sheet in the North Atlantic Ocean, the improvement in snow cover and the powerful volcanic eruptions that they may have combined in combination led to a intense cooling of the northern hemisphere. “
Analysis of the chemicals found in the Hall’s Cave soil in Texas Hill Country found traces of rare elements, including osmium, iridium, ruthenium, platinum, palladium and rhenium.
However, they were not in the “correct” quantities that would have been added by a meteor or asteroid.
Instead, geosignatures indicated a volcanic origin, not extraterrestrial.
In the photo, archaeological excavations in Hall’s Cave. Experts exhibited sediments for geochemical analyzes ranging from around 20,000 to 6,000 years ago
Seemingly benign volcanoes can be much more violent than previously feared
A study shows that volcanoes that appear to be benign can be far more violent than previously feared due to volatile magma hidden deep beneath the surface.
Scientists studied volcanoes on remote islands of the Galapagos archipelago in the Pacific Ocean off the coast of Ecuador.
They found volcanoes that reliably produce small basalt lava eruptions, an igneous rock, hiding chemically different magmas in their underground hydraulic systems.
These include some that have the potential to generate “explosive activities” and may pose an unexpected security risk to local authorities in the future.
Principal PhD student Nan Sun, of the University of Houston, said: The signature of the isotopic analysis of osmium and the relative proportion of the elements corresponded to those previously reported in volcanic gases. “
Co-author Dr Kenneth Befus also at Baylor University added: ‘These signatures were probably the result of large eruptions in the northern hemisphere, including volcanoes in the Aleutians, in the Falls and even in Europe.
Experts say the cooling down period lasted around 1,200 years, too long to have been caused by a single event.
Professor Forman said: “A single volcanic eruptive cause is an important trigger, but other changes in the Earth’s system, such as cooling the oceans and more snow cover, have been needed to sustain this colder period.
“This isn’t the first time that scientists have looked at other explanations for the sudden cooling.”
The researchers doubted their theory in the face of the evidence, but after studying all the possible explanations for cooling, the only viable explanation was a volcanic one.
Professor Brandon said: ‘I was skeptical. We have gone out of our way to find an alternative explanation or even avoid this conclusion.
“A volcanic eruption had been considered a possible explanation, but was generally rejected because there was no associated geochemical footprint.”
The results were published in the journal Science Advances.