What was 1816, the Year Without a Summer?

In 1816, much of Europe and northeastern North America had a cold, sunless summer that ruined crops. Evidence points mainly to the April 1815 eruption of Mount Tambora in Indonesia, which put ash and aerosols into the atmosphere and cooled the climate. The result was food shortages, higher prices, riots, disease, migration and some cultural consequences. [1] [2]

Mount Tambora, on the island of Sumbawa, began erupting in April 1815 and is described as the largest volcanic explosion in recorded history. Heavy ash fell near the volcano, but lighter particles reached the stratosphere and spread around the world, blocking sunlight. According to [scied.ucar.edu](https://scied.ucar.edu/learning-zone/how-climate-works/mount-tambora-and-year-without-summer), the effect was temporary, because the particles eventually fell out of the atmosphere. [3] [2]

The sources give different figures for the cooling. The BBC and the Center for Science Education cite about 3 degrees Celsius on average, while Wikipedia gives 0.4 to 0.7 degrees Celsius for the global average. The figures may reflect different regions or measures, and the results do not explain the gap. [2] [3] [1]

In the northeastern United States, frost in May killed crops in New York, Massachusetts, New Hampshire and Vermont. Snow fell in June in Albany and in Dennysville, Maine, and frost lingered in Virginia into late August, according to the [nps.gov](http://nps.gov/articles/000/1816-the-year-without-summer.htm) account. [4]

In Britain, a persistent north-westerly airflow brought cold, wet, often sunless weather. The Central England Temperature series records July 1816 as the coldest July on record, and snow fell in the Midlands in mid-May. Across Europe, summer temperatures were the coldest recorded between 1766 and 2000. Crops failed in Ireland, and in China the disrupted monsoon contributed to a three-year famine in Yunnan. Not everywhere cooled: warmer air reached the Arctic. [2] [1]

Food prices rose sharply across Europe. Hungry crowds gathered at grain markets and bakeries, and the food riots of 1816 and 1817 were reportedly the most violent on the continent since the French Revolution. Typhus epidemics followed the famine between 1816 and 1819, killing more than 65,000 people as the disease spread out of Ireland. [1]

In the United States, frozen soil and high prices prompted migration westward. Wikipedia says many thousands left New England for western New York and the Northwest Territory, and notes that Indiana became a state in December 1816. The historian Lawrence Goldman has suggested that migration into upstate New York helped center the abolitionist movement there. [2] [1]

Expensive oats made horses costlier to keep, and this may have pushed Karl Drais toward horseless transport, leading to the draisine and a precursor of the bicycle. The sources hedge with 'may have', so the link is suggestive rather than established. [3] [1]

At Lake Geneva that summer, rain kept Mary Shelley, Percy Shelley and Lord Byron indoors. Shelley wrote Frankenstein, and Byron wrote the poem Darkness, which opens with the bright sun extinguished. [3]