How Early Humans Survived The Toba Eruption

Despite the climate impacts of the Toba eruption 74,000 years ago, our early ancestors in Africa were likely shielded from the catastrophe’s worst effects.

AsianScientist (Jul. 21, 2021) – Here’s some good news: it turns out that early human populations were shielded from the worst impacts of one of the world’s largest volcanic eruptions. These findings are reported in the Proceedings of the National Academy of Sciences of the United States of America.

Nearly 74,000 years ago in what is now known as North Sumatra, Indonesia, the Toba supervolcano erupted—with catastrophic consequences. In scenes straight out of a Hollywood disaster movie, the Toba eruption is believed to have wiped out most of the humans living at the time and caused a global volcanic winter lasting almost a decade. However, what actually happened during the Toba eruption remains a mystery to this day.

“We know this eruption happened and that past climate modeling has suggested the climate consequences could have been severe, but archaeological and paleoclimate records from Africa don’t show such a dramatic response,” explained lead author and assistant professor Benjamin Black from Rutgers University-New Brunswick

To finally resolve the debate surrounding the eruption’s impact on climate and human evolution, Black and his colleagues virtually turned back the clock—simulating Toba’s effects through climate models.

Accordingly, the team analyzed 42 global climate models, varying factors like the magnitude of sulfur emissions, the time of year of the eruption and background climate state. In contrast to the international Armageddon-like scenario painted by past studies, their results suggest that climate impacts were likely significant different across the globe.

For instance, while the Northern Hemisphere may have experienced cooling ranging from 4 to 10°C, cooling in the Southern Hemisphere was unlikely to exceed 4°C even under the most severe eruption conditions.

“Our results suggest that we might not have been looking in the right place to see the climate response. Africa and India are relatively sheltered, whereas North America, Europe and Asia bear the brunt of the cooling,” said Black.

Ultimately, their findings account for independent archaeological evidence suggesting the Toba eruption had modest effects on the development of early human species in Africa. With this in mind, the authors say that their ensemble simulation approach could be used in the future to better understand other past and future explosive eruptions.

“Our results reconcile the simulated distribution of climate impacts from the eruption with paleoclimate and archaeological records. This probabilistic view of climate disruption from Earth’s most recent super-eruption underscores the uneven expected distribution of societal and environmental impacts from future very large explosive eruptions,” concluded the authors.

The article can be found at: Black et al. (2021) Global Climate Disruption and Regional Climate Shelters After the Toba Supereruption.


Source: Rutgers University; Photo: Shutterstock.
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