Less Disaster

The last great catastrophe probably wasn’t as bad as we’d thought:

Toba is a supervolcano … eruption, 74,000 years ago, … Releasing 2500 cubic kilometres of magma – nearly twice the volume of mount Everest … the largest eruption on Earth in the last 2 million years … Previous computer models … suggested global temperatures dropped by about 10 °C following the blast.  This supports the idea of a decade-long “volcanic winter” and widespread catastrophe. … Modern humans, … would have been whittled down to just a few thousand breeding pairs scattered in dispersed refugia. …

Graf and his colleagues suggest a new estimate of global cooling of just 2.5 °C, which lasted for just a few years. … In places like India the average temperatures may only have fallen by about 1 °C. …

Recent archaeological and geological work in India seems to support Graf’s claims. .. Had there been a sudden deforestation event … topsoil no longer anchored by trees would be expected to wash down into valleys. … “We don’t find a rapid influx of soil arriving on top of the ash layers.” … [A] hunter-gatherer camp … has yielded more than 1800 tools, … hominin life appeared to continue in the same vein immediately after the eruption, with hundreds more stone tools in the layers immediately above the ash fall.  The team uncovered a similar story 1000 kilometres further north … “We see very little change in tool technology across the Toba ash.”

If last near-existential disaster wasn’t as bad as we’d thought, maybe our existential risk is a bit less than we’d thought.  Not big news, but good news even so.

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