Mount Pinatubo erupted in the Philippines in 1991, spewing millions of tons of ash and chemicals into the atmosphere. Over the next year, large parts of Earth cooled by almost a full degree Fahrenheit.
Volcanoes historically have caused some of the planet’s sharpest temperature drops. In addition to ash and fire, they belch sulfur dioxide that lingers as a fine particle spray called an aerosol. These aerosols help Earth’s atmosphere reflect incoming light, creating a cooling effect.
