Mount Toba eruption (~74.000 years ago) and southern Africa

Mount Tambora erupted in 1815 and has been responsible for a year without summer in 1816. The impact on the human population was dire – crop failures in Eurasia and North America, famine and mass migrations.

The eruption of Mount Toba, some 47.000 years ago, was a hundred times more massive than that of Mount Tambora[1]. The effects would have had a much larger, and longer-felt, impact on people around the globe.

The scale of the ash-fall alone attests to the magnitude of the environmental disaster. Huge quantities of aerosols injected high into the atmosphere would have severely diminished sunlight – with estimates ranging from a 25 to 90 percent reduction in light. Under these conditions, plants die-off, large herbivores starved and provided little sustenance to the predators, both carnivores and humans, that depended on them. The cycle repeated itself, year after year.

Recently archaeologists discovered microscopic glass shards (cryptotephra) characteristic of the ashfall from the Toba eruption in two sites (the Pinnacle Point rockshelter and an open air site some 10 kilometers away called Vleesbaai) on the south coast of South Africa[2]. The study also shows that along the food-rich coastline of southern Africa, humans thrived through this mega-eruption, perhaps because of the uniquely rich food regime on this coastline. Around 'neighbouring' Lake Malawi humans also thrived[3].

In the 1990s, scientists began arguing that this eruption of Mount Toba, the most powerful in the last two million years, caused a long-lived volcanic winter that may have devastated the ecosystems of the world and caused widespread population crashes, perhaps even a near-extinction event in our own lineage, a so-called bottleneck.

[1] Williams: The ∼73 ka Toba super-eruption and its impact: history of a debate in Quaternary International – 2012
[2] Smith et al: Humans thrived in South Africa through the Toba eruption about 74,000 years ago in Nature – 2018
[3] Lane et al: Ash from the Toba supereruption in Lake Malawi shows no volcanic winter in East Africa at 75 ka in Proceedings of the National Academy of Sciences of the United States of America - 2013