Toba Catastrophe Theory

Histories of Humans and Climate
. 4 minutes .

  • 76.000 years ago, in Lake Toba, Indonesia: a supervolcanic eruption causes one of the worst climatic disasters mankind ever had to overcome.
  • The Toba catastrophe theory posits that this event caused a global volcanic winter of several years.
  • Science journalist Ann Gibons suggested it created the evolutionnary bottleneck that allowed Sapiens to develop.

The tale:

“As soon as they are brought to excavate a dig site, paleontologists look for a distinguishable continuous feature: a black layer of nine meters thick in Indonesia, stretching to a few millimeters at the poles. In the chronology of sedimentary deposits, this line marks a date known to all specialists: 74,000 years BC. At that time, a gigantic volcano had erupted: it is called Toba. The ashes that gushed out of its crater covered the entire globe. Wherever we dig, their deposit forms this continuous line, the last remnant of an explosion that nearly annihilated our species.

Before, humans feared nature. They were afraid of it by experience. Cyclones,
earthquakes, or volcanic eruptions would leave traces in our collective memory. We suffered its violence with powerlessness and incomprehension. Evil gods were invented and we started attributing these cataclysms to their anger. It brought us to our knees, then we dressed our wounds. Our survival instinct is more than mere despair. Our immense capacity to adapt put us back on our feet. Our collective intelligence helped us move forward.

In Sumatra, the eruption of Toba was so powerful that the human species almost
disappeared. We were more than a million humanoids, three thousand survived.”

Introduction of the 2nd chapter of “Founding Disasters“:

The science:

In 1993, science journalist Ann Gibbons posited that a population bottleneck occurred in human evolution about 70,000 years ago, and she suggested that this was caused by an eruption. Geologist Michael R. Rampino of New York University and Stephen Self of the University of Hawaiʻi support her theory.

In 1998, the bottleneck theory was further developed by anthropologist Stanley H. Ambrose of the University of Illinois. Both the link and global winter theories are controversial. The Youngest Toba eruption is the most closely studied supervolcanic eruption.
Wikipedia extract

Instagram caption

What if Toba Erupted Today?

“If the Toba caldera volcano were to explode now, the impact would be quite different. The volcano would project billions of tons of ejections into the stratosphere. A thick layer of ashes and sulfuric acid would form, which would mask the sun. Average temperatures on earth would only drop by 10°C. After ten years, this global cooling would be only two degrees. Rainfall would decrease by about 45% for several years.

Those who have financial means could endure this sudden cold: they would buy warmer clothes, consume more heating and pay dearly for fresh water and food. To give a more concrete order of magnitude: an inhabitant of Naples will have to live for two years as in winter in Montreal and then, for about ten years, as someone living in Hamburg, Germany. Two years of continuous night and intense cold will affect his morale. The intense dust that will be everywhere, even in his bronchial tubes, may weigh him down. Some ash damage will complicate things: house roofs will collapse under the weight, power lines too. Traffic conditions will become… difficult. The pipes are likely less insulated in Naples than in Montreal: they will burst. There will be an insufficient number of Italian snowplows.

Stress could be hard to bear but there will be no danger for this Neapolitan’s survival: the cold will not kill him. The person who lives in Moscow today is likely to have more difficulty adapting to a temperature drop of about 15 degrees. He will perhaps rush to the option of climate emigration towards the south.

Introduction of “What if Toba Erupted Today”, in “Founding Disasters.


  • Introduction
  • A volcano with a caldeira
  • How many survivors?
  • Conquering the world
  • What if Toba erupted today
  • The Major risk is Starvation
  • Are there any Other Volcanoes with a Caldera

Table of content of the 2nd chapter of “Founding Disasters“:

Founding Disasters, book about the history of climate and humans.

Extracts from:

Founding Disasters, by Christophe Olivier

ePub/PDF – 12 languages – 70 pages
Cover picture : “Cells” by Agata Orlowska, Cc by-nc 4.0

What’s happening to our climate ? How fast is it changing, what should we expect ? “When you don’t know where you’re going“, goes the Wolof proverb, “look where you’re coming from“. So let us look!

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