In 1815, The Largest Eruption In Recorded History Plunged Earth Into A Volcanic Winter

The idea that a volcano could send the planet into a long-lasting winter might feel like something that only happened in the distant past or slightly dodgy disaster movies, but in the early 19th century, that very thing happened. The culprit? Mount Tambora, and it was responsible for the largest volcanic eruption in recorded history.

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A stratovolcano (the taller, more conical ones as opposed to gently sloped shield volcanoes like Kīlauea), occupies a 60-kilometer (37-mile) wide stretch of the Indonesian island of Sumbawa, jutting out on its Sanggar Peninsula.

Eruptions aren’t unusual here. Mount Tambora sits within the Sunda Arc, a large chain of active volcanic islands formed by the sliding of one tectonic plate (the Indo-Australian Plate) beneath another (the Eurasian Plate), known as subduction.

In fact, Tambora had already been rumbling away for a few years before its historic eruption. But in April 1815, the intensity of this eruptive episode really kicked into gear. 

Peaking on April 10 and 11, the volcano ejected an estimated more than 150 cubic kilometers (36 cubic miles) of material, in a series of violent explosions that led to the eruption being rated a 7 on the Volcanic Explosivity Scale (VEI) – that’s the second-largest rating on the scale, with only supervolcanic eruptions above. For comparison, the 1980 eruption of Mount St. Helens – the deadliest in US history – was a VEI 5. 

What does an eruption that big look like? Hellish is definitely one way to describe it; there were huge, high-rising ash plumes that dropped on the surrounding croplands, and pyroclastic flows that pummeled down towards the sea, wiping out entire villages on the way and causing further devastation via tsunamis once they reached the water. In total, it’s thought that the event killed an estimated 60,000-70,000 people.

But the impact of Tambora’s eruption would not just be felt while it was occurring and in the immediate aftermath. In the chaos of a volcanic eruption, sulfur dioxide is spat out into the atmosphere, where it can remain for months on end, mixing with water to produce aerosolized sulfuric acid. These fine aerosol droplets reflect sunlight back into space, leading to the cooling of Earth’s lower atmosphere.

The 1815 eruption produced 60 megatons of sulfur, and as a result, average global temperatures dropped by around 3°C (5.4°F). However, the most extreme effects of this change in climate were seen in the Northern Hemisphere, which in 1816 experienced what became known as “The Year Without Summer”.

While the actual winter months had been unremarkable, the cold weather didn’t end up letting up. In the US, for example, New York saw heavy snow in June, and lakes and rivers in northwestern Pennsylvania were still frozen in July. Over in Europe, it reportedly didn’t stop raining in Ireland for eight consecutive weeks, while in Asia, disruption of the monsoon season led to droughts.

The upheaval had devastating effects, leading to crop failures, famine, disease outbreaks, and rioting, likely causing further deaths.

If that’s not a case for the awesome power of volcanoes, we don’t know what is.