74,000 years ago, the mega-eruption of the Toba volcano in Indonesia may have transformed Earth’s climate into a new glaciation. However, this disastrous scenario has been called into question by a new study. It will not be a single and cataclysmic eruption lasting a few days, but on the contrary a long eruption sequence lasting several tens of thousands of years!
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The Quaternary period (-2.6 million years) is marked by a series of glaciations. Correlation of these climate changes with Milankovitch cycles suggests that they are primarily caused by variations in Earth’s orbital parameters. But it cannot be ruled out that some factors can influence the transition between warm and cold periods. Toba, an Indonesian volcano on the island of Sumatra, is suspected to have disrupted Earth’s climate about 74,000 years ago, hastening Earth’s entry into a new ice age. The Toba caldera is actually the largest in the Quaternary and suggests that the volcano experienced exceptionally powerful eruptive activity. Between 2,800 to 5,300 km3 Along with the magma, a large amount of ash would have been emitted, which today is found in a large part of the sedimentary deposits of the Southern Hemisphere. These massive releases of particles and gases into the atmosphere would have caused a volcanic winter, affecting the climate at a critical moment of the last interglacial-glacial transition.
multi-stage volcanic activity rather than a single super-eruption
To many scientists, this volcanic activity would have been short-lived, only a few days, thus akin to a super-eruption. However, debate remains open regarding the exact sequence of events. A new study questions this scenario involving a single and catastrophic explosion.
Recent geochemical analysis of polar ice cores actually suggests that there was not one, but several Toba eruptions around 74,000 years ago. However, the identification of the volcano in question remained elusive. Benoît Caron of the Institute of Earth Sciences in Paris and his colleagues eventually confirmed this hypothesis by analyzing marine sediments and volcanic deposits recovered from Sumatra, which is apparently attributed to Toba. Thus the researchers were able to identify 17 different volcanic events. They are classified into three major successive eruption phases that occurred between 103,000 and 76,000 years ago with the first (seven separate eruptions), between 76,000 and 65,000 years ago the second (six separate eruptions) and between 65,000 and 48,000 years ago. Were in between. Final (four separate explosions).
greater impact on climate than a powerful but small eruption
Toba may therefore not have experienced a single super-eruption, but rather a long sequence of different volcanic phases, each consisting of several eruptive events. Therefore the entire eruptive history of this volcano has been revisited. The results were published in the journal scientific report,
The peak of intensity appears to have occurred during the second phase, between 76,000 and 65,000 years ago, at the transition to the last glacial period. These results therefore support the idea that repeated eruptions of Toba may have indeed caused a new glacial ingress. This new scenario is more plausible than a single super-eruption of very short duration, whose effect on climate would have been much less significant than that of nearly continuous volcanic activity over a period of several tens of thousands of years.
This new study sheds light on how multiphase volcanic activity could have an impact on the planet’s global climate. Toba’s activity may have played a major role in human evolution by subjecting humans to volcanic and climatic stress, forcing them to adapt. This period is also considered crucial in the development ofa wise man,
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