Support WBURScientific Pros Weigh The Cons Of Messing With Earth's ThermostatPlay04:22Download AudioNell GreenfieldboyceFebruary 10, 2015 ShareThe eruption of Mount Pinatubo in the Philippines in 1991 spewed almost 20 million tons of sulfur dioxide into the atmosphere, causing worldwide temperatures to drop half a degree on average. (AFP/Getty Images)
