certain, much rarer eruptions—Mount Pinatubo among them—send high volumes of sulfur dioxide all the way up to the stratosphere. When that happens, the sulfuric acid droplets don’t fall back down: they remain in the stratosphere, and within weeks can circulate to surround the entire planet. The droplets act like tiny, light-scattering mirrors, preventing the full heat of the sun from reaching the planet’s surface. When these larger volcanic eruptions occur in the tropics, the aerosols stay suspended in the stratosphere for roughly one to two years, and the global cooling effects can last even
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