Doubt over 'volcanic winter' after super-eruption

New research from Oxford University casts doubt on the theory that the Mount Toba super-eruption, which took place at the Indonesian island of Sumatra 75,000 years ago, could have plunged the Earth into a volcanic winter leading to the near extinction of early humans.

A fresh analysis of volcanic ash recovered from lake sediment cores in Lake Malawi in East Africa shows that the eruption spewed ash much further than studies have previously found. Other theories have said that the explosive volcanic eruption may have triggered a chain of climatic events resulting in a cooling of temperatures, but this latest study finds no evidence of a significant dip in temperatures in East Africa at the time. The findings are published in the early edition of the journal Proceedings of the National Academy of Sciences.

The researchers from Oxford University and the University of Minnesota in Duluth, USA, examined microscopic volcanic ash recovered from sediment extracted from two sites in Lake Malawi in the East African Rift Valley, around 7,000 kilometres west of the source of the Toba eruption. Their analysis showed that the thin layer of ash deposits revealed in the sediment cores was from the last of the Toba eruptions – known as Youngest Toba Tuff (YTT)....