[askl56]

The explosive eruption of Mt. Pinatubo in 1991 injected enough sulfur-containing compounds into the stratosphere to substantially reduce the amount of sunlight reaching Earth's surface. In response to the increased reflectivity of the planet, the surface temperature cooled by about 0.3°C during 1992, with temperatures returning to their normal levels by 1994. But what happens when a much, much large eruption occurs?

Roughly 74,000 years ago, a "super-eruption" took place in Indonesia, the largest know eruption in the past 100,000 years. The Toba eruption was enormous, throwing out roughly 1000 times as much rock as the 1980 eruption of Mt. St. Helens (Fig. 1). Dust trapped in polar ice cores shows that ejected material spread around the globe, indicating that the eruption injected substantial material into the stratosphere, where it can strongly affect climate. How much and for how long the Toba eruption actually affected climate and life on the Earth's surface has been the subject of intense debate.

https://www.giss.nasa.gov/research/briefs/shindell_12/