The ‘Year Without a Summer’

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April 1, 2013

In many parts of the country winter refuses to release its icy grip, and records are being broken for spring’s late arrival. Although we know that spring and summer will come eventually, we are still a far cry from rivaling the “Year Without a Summer.”

That year was 1816. It was near the end of the Little Ice Age, a period that began around 1350 AD. It was also in the middle of what became known as the Dalton Minimum, an unusual period of low solar activity named after English meteorologist John Dalton that lasted from 1790 to 1830.

But the main contributor to the unusually cold year was the volcanic winter caused by the eruption of Mount Tambora, located on the island of Sumbawa, Indonesia. In April of 1815, it erupted in what was one of the two largest eruptions in the past 2000 years, and the largest eruption in recorded history. This eruption had a Volcanic Explosivity Index (VEI) of 7, which is a supercolossal event. The highest VEI number ever assigned has been an 8, a mega-colossal event — an example is the Yellowstone eruption in 640,000 BC. For point of reference, the eruption of Mount St. Helens ranks a 5 on the logarithmic scale.

The amount of volcanic ash spewed into the atmosphere by Mount Tambora lowered global temperatures by as much as 0.7–1.3 °F. Much cooler temperatures in many parts of the world the year after the eruption led to worldwide harvest failures, which is why that year is also known as the “Poverty Year.”

The parts of the world most affected were the northeastern United States and Canada, and parts of Western Europe. The northeastern U.S. was enveloped in a persistent dry fog known as a “stratospheric sulfate aerosol veil” due to the sulfur that was discharged into the atmosphere from the eruption. Neither wind nor rain would disperse this fog that reddened the daylight and made it possible for people to observe sunspots with the naked eye.

Snow fell on June 6, 1816 in New York and Maine, while Quebec City received nearly a foot of snow. June frost led to widespread crop failure, which led to high prices as well as a food shortage. Ice could be found on lakes and rivers as far south as Pennsylvania in the month of August.

Across the pond, cooler- and wetter-than-normal conditions led to the failure of the crop harvests for potatoes, wheat, and oats in Ireland and Great Britain, leading to the worst famine of the century. Frost was present throughout the summer months. Hungary saw brown snow, while Italy saw red snow, both due to the volcanic ash in the atmosphere. London also reported snow — in August.

The Far East was not immune. China’s rice crop suffered due to unusually low temperatures leading to famine there as well, and snowfall was reported during the summer. Snow and frost were even reported in Taiwan, which is normally tropical.

The explosion of Mount Tambora was heard up to 1,600 miles away. Ash fell over 800 miles away. The volcanic eruption has been blamed for up to 71,000 deaths. Besides the famine caused by the temporary climate change, the volcanic eruption is also blamed for the severity of the typhus epidemic in Europe and the Mediterranean in the years immediately following; and for a new strain of cholera that broke out in India because the normal monsoon season was disrupted.

The U.S. saw a migration of farmers from the New England states to the Midwest as one of the major long term effects of the eruption; and it was during that cold, rainy summer in Geneva, Switzerland that Mary Shelley began writing her most famous work: the novel Frankenstein.

http://membercentral.aaas.org/blogs/scientia/year-without-summer

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