How the rumbling Bali volcano could temporarily cool the globe

Scientists are carefully watching the eruption of Mount Agung, the Bali volcano that has spewed ash at least four miles into the sky and is now shaking the popular vacation island with violent tremors.
These earthquakes may portend an even greater eruption, as massive amounts of pressurized, heated magma swirl beneath the volcano. 
Already, Mount Agung has affected the local populace, prompting evacuations and tainting the air. But explosive volcanoes like this one, which last had a major e