The VEI is used to quantify the amount of ejected material, with a VEI-7 being . Every index value below that is one order of magnitude (meaning, ten times) less. Furthermore, the 1815 eruption occurred during a Dalton Minimum, a period of unusually low solar radiation. Volcanism plays a large role in climate shifts, both locally and globally. This was not always understood and did not enter scientific circles as fact until Krakatoa erupted in 1883 and tinted the skies orange.