EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Toba volcano super eruption destroyed the ozone layer and caused a human population bottleneck

Sergey Osipov1, Georgiy Stenchikov2, Kostas Tsigaridis3,4, Allegra LeGrande3,4, Susanne Bauer3,4, Mohamed Fnais5, and Jos Lelieveld1
Sergey Osipov et al.
  • 1Max Planck Institute for Chemistry, Mainz, Germany (
  • 2King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
  • 3Center for Climate Systems Research, Columbia University, New York, USA
  • 4NASA Goddard Institute for Space Studies, New York, USA
  • 5King Saud University, College of Science, Riyadh, Saudi Arabia

Volcanic eruptions trigger a broad spectrum of climatic responses. For example, the Mount Pinatubo eruption in 1991 forced an El Niño and global cooling, and the Tambora eruption in 1815 caused the "Year Without a Summer." Especially grand eruptions such as Toba around 74,000 years ago can push the Earth's climate into a volcanic winter state, significantly lowering the surface temperature and precipitation globally. Here we present a new, previously overlooked element of the volcanic effects spectrum: the radiative mechanism of stratospheric ozone depletion. We found that the volcanic plume of Toba enhanced the UV optical depth and suppressed the primary formation of stratospheric ozone from O2 photolysis. Sulfate aerosols additionally reflect the photons needed to break the O2 bond (λ < 242 nm), otherwise controlled by ozone absorption and Rayleigh scattering alone during volcanically quiescent conditions. Our NASA GISS ModelE simulations of the Toba eruption reveal up to 50% global ozone loss due to the overall photochemistry perturbations of the sulfate aerosols. We also consider and quantify the radiative effects of SO2, which partially compensated for the ozone loss by inhibiting the photolytic O3 sink.

Our analysis shows that the magnitude of the ozone loss and UV-induced health-hazardous effects after the Toba eruption are similar to those in the aftermath of a potential nuclear conflict. These findings suggest a “Toba ozone catastrophe" as a likely contributor to the historic population decline in this period, consistent with a genetic bottleneck in human evolution.

How to cite: Osipov, S., Stenchikov, G., Tsigaridis, K., LeGrande, A., Bauer, S., Fnais, M., and Lelieveld, J.: Toba volcano super eruption destroyed the ozone layer and caused a human population bottleneck, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4131,, 2020


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