In 1991, Mount Pinatubo in the Philippines erupted in one of the largest volcanic blasts of the 20th century. It spat up to 20 million tons of sulfur into the upper atmosphere, shielding the earth from the sun’s rays and causing global temperatures to drop by nearly half a degree Celsius in a single year. That’s more than half of the amount the planet has warmed due to climate change in 130 years.