In the summer of 1816, the world experienced a significantly cooler summer than expected. The average global temperature that summer dropped 0.7-1.3 degrees Fahrenheit (0.4-0.7 degrees Celsius). When looking at the daily temperature and planning for an outing to the beach, a couple of degrees might not seem like a lot, but over an entire region and for an entire season, a temperature variation that significant can, and did, have catastrophic effects.
A significant portion of the Northern hemisphere, including Western Europe and the Eastern side of North America, like Alberta, Canada and the New England area of the United States, experienced crop failures and food shortages. The situation is best described as an agricultural disaster where sinking summer temperatures decimated crops and triggered what is considered the last great subsistence crisis in the Western world.
Entire segments of the population in Wales were reduced to refugee status, traveling for food. Ireland experienced sweeping crop failures. Germany also experienced severe food shortages. The cold reached well beyond Europe, however, and as far away as China, the cold weather was severe enough to kill trees, crops, and livestock. Changes in ice formation and volume also lead to the destruction of dams and flooding in many locations around the world.
So what caused “The Year Without a Summer” as the cool period was called? For centuries leading up to the event, the Earth had already been cooling, a period starting in the 14th century and dubbed “The Little Ice Age”. This slow cooling had already caused agricultural upset in Europe, but the real trigger for the “Year Without a Summer” was the enormous 1815 eruption of Mount Tambora in the Dutch East Indies. It was the largest volcanic eruption that had occurred in at least 1,300 years and the ejected debris and dust was the trigger for the weather patterns and changes in heat absorption from the sun that caused the sudden global cooling.