Sulfur Dioxide (SO2)
17 million tonnes of SO2 was released into the stratosphere after an eruption of Mount Pinatubo in 1991. The sulfur aerosols resulted in a 0.5-0.6oC cooling of the Earth's surface in the Northern Hemisphere.
The sulfate aerosols also accelerated chemical reactions that, together with the increased CFC levels, destroyed ozone and led to some of the lowest ozone levels ever observed in the atmosphere.