Tambora erupts

The eruption of Mount Tambora in Indonesia threw so much ash and gas into the air that global temperatures dropped. 1816 became known as the Year Without a Summer.

Context

Mount Tambora, on the Indonesian island of Sumbawa, erupted in April 1815, with the climactic explosion on 10 April. It is the largest volcanic eruption in recorded history. The mountain lost well over a thousand metres of height, and ash, pumice and the flows that followed killed many thousands of people nearby; with the famine and disease that came afterwards, estimates of the total are far higher and uncertain.

The gas that mattered most for the rest of the world was sulfur dioxide. It formed a haze of tiny droplets in the upper atmosphere that reflected sunlight and cooled the planet. The following year, 1816, brought a cold, wet summer in much of Europe and North America, with crop failures, high food prices and unusual late frosts. Volcanic cooling was probably not the only factor, but it is considered the main one.

The gloomy summer of 1816 is also remembered in literature: Mary Shelley began writing Frankenstein that year while kept indoors by bad weather at Lake Geneva.

Tambora is a standard case in climate science for how a single eruption can change weather worldwide for a year or more, and it is used to test models of how large future eruptions might affect harvests and food supply.