It has been conjectured that the changes were caused by ashes or dust thrown into the air after the eruption of a volcano (a phenomenon known as "volcanic winter"),[20] or after the impact of a comet[21] or meteorite.[22][23] The evidence of sulfate deposits in ice cores strongly supports the volcano hypothesis; the sulfate spike is even more intense than that which accompanied the lesser episode of climatic aberration in 1816, popularly known as the "Year Without a Summer", which has been connected to the explosion of the volcano Mount Tambora in Sumbawa.[5]