In 1816, Europe and North America were plagued by heavy rains, odd-colored snow, famines, strange fogs and very cold weather well into June. Though many people believed it to be the apocalypse, this "year without a summer" was actually the result of a supervolcano eruption that happened one year earlier over 1,000 miles away. Alex Gendler describes the history and science of these epic eruptions. [4:50]