Ancient volcano caused 10-year winter

NEW BRUNSWICK, N.J., July 8 (UPI) -- U.S. scientists said they have determined the eruption of Indonesia's Toba volcano about 74,000 years ago triggered a decade-long severe winter.

Previous studies suggested the massive eruption produced a 1,000-year episode of ice sheet advance, as well as a "volcanic winter," which most likely would have drastically reduced the human population at the time.

To investigate additional mechanisms that might have enhanced and extended the effects of the Toba eruption, Rutgers University Professor Alan Robock and colleagues conducted six climate model computer simulations using state-of-the-art models that include vegetation death effects and stratospheric chemistry feedback that might affect the lifetime of the volcanic cloud.

The researchers said they used a variety of aerosol injection simulations ranging up to 900 times that of the 1991 Mount Pinatubo eruption in the Philippines.

The scientists said none of the models initiated glaciation, but they did produce a decade of severe volcanic winter that would likely have devastated humanity and global ecosystems.

The study that included Georgiy Stenchikov Caspar Ammann, Samuel Levis, Luke Oman and Drew Shindell appears in the Journal of Geophysical Research-Atmospheres.