Some might recall the Summer 1991 eruption of Mount Pinatubo in the Philippines. This epic volcano sent an enormous volume of ash across the globe, ultimately altering the world's climate.
The eruption of Pinatubo resulted in a reduction in the normal amount of sunlight reaching the Earth's surface by roughly 10 percent in 1991 — 1992, which led to a decrease in northern hemisphere average temperatures of more than 1°F, and a global fall of about .7°F. Doesn't seem like much right? But on a global scale the impact was nearly as big as the volcano itself!
Well, Iceland's Eyjafjallajökull volcano doesn't promise to be as big a deal when it comes to climate change. While the volcano is treating European sky watchers to spectacular sunsets and hampering air travel, as determined by NASA's Aura Satellite, the amount of sulfur dioxide spewed by the volcano so far poses no threat globally. This is mostly because the current plume is below the stratosphere, where volcanic gases can have large-scale weather effects due to the lack of rain there that prohibits the removal of volcanic material. Experts verify this and expect that the destination and duration of the volcanic plume will be altered by rain and winds and it should be washed away as it continues to drift east, likely never even impacting the United States.
However, the potential for Eyjafjallajökull to impact the Earth's climate is still there if it begins to erupt more violently. An eruption of an Icelandic volcano called Laki in 1783 had large effects on climate. It created a long-lasting haze over Europe, cooled temperatures globally and altered monsoon flows that created droughts and famines in Egypt and India.