Mount Tambora’s 1815 eruption created the volcanic climate effects known as the “Year Without a Summer.”
Tambora is on Sumbawa Island in present-day Indonesia. Its eruption began in April 1815 and is commonly classified as a magnitude-7 event on the volcanic explosivity index, making it one of the largest eruptions in recorded history.
The eruption injected enormous quantities of ash and sulfur gases into the stratosphere. Sulfur dioxide formed sulfate aerosols that reflected sunlight, lowering average temperatures across parts of the Northern Hemisphere in 1816. The resulting frosts, heavy rains and harvest failures inspired the phrase “Year Without a Summer.”
The eruption also devastated communities near the volcano and killed many people through ashfall, pyroclastic flows, disease and famine. It was far larger than the 1883 Krakatoa eruption in the amount of material ejected.