Year Without a Summer

In China, the cold weather killed trees, rice crops, and even water buffalo, especially in the north. Floods destroyed many remaining crops. The monsoon season was disrupted, resulting in overwhelming floods in the Yangtze Valley. In India, the delayed summer monsoon caused late torrential rains that aggravated the spread of cholera from a region near the Ganges in Bengal to as far as Moscow.[7] In Japan, still exercising caution after the cold weather related Great Tenmei famine of 1782–1788, the cold damaged crops, but no crop failures were reported, and there were no adverse effects on population.[8]

Sulfate concentration in ice cores from Greenland. An unknown eruption occurred before 1810.[9] The peak after 1815 was caused by Mount Tambora.

The aberrations are now generally thought to have occurred because of the April 5–15, 1815, Mount Tambora volcanic eruption[10][11] on the island of Sumbawa, Indonesia.[12] The eruption had a volcanic explosivity index (VEI) ranking of 7, a colossal event that ejected at least 100 km³ (24 cu mi) of material. It was the world's largest since the eruption of Paektu Mountain in 946 AD.

Other large volcanic eruptions (with VEIs at least 4) around this time were:

• 1808, the 1808 mystery eruption (VEI 6) in the southwestern Pacific Ocean
• 1812, La Soufrière on Saint Vincent in the Caribbean
• 1812, Awu in the Sangihe Islands, Dutch East Indies
• 1813, Suwanosejima in the Ryukyu Islands, Japan
• 1814, Mayon in the Philippines

These eruptions had built up a substantial amount of atmospheric dust. As is common after a massive volcanic eruption, temperatures fell worldwide because less sunlight passed through the stratosphere.[13]

According to a 2012 analysis by Berkeley Earth Surface Temperature, the 1815 Tambora eruption caused a temporary drop in the Earth's average land temperature of about 1 °C. Smaller temperature drops were recorded from the 1812–1814 eruptions.[14]

The Earth had already been in a centuries-long period of global cooling that started in the 14th century. Known today as the Little Ice Age, it had already caused considerable agricultural distress in Europe. The Little Ice Age's existing cooling was exacerbated by the eruption of Tambora, which occurred near the end of the Little Ice Age.[15]

This period also occurred during the Dalton Minimum (a period of relatively low solar activity), specifically Solar Cycle 6, which ran from December 1810 to May 1823. May 1816 in particular had the lowest sunspot number (0.1) to date since record keeping on solar activity began. The lack of solar irradiance during this period was exacerbated by atmospheric opacity from volcanic dust.

Low temperatures and heavy rains resulted in failed harvests in Britain and Ireland. Families in Wales traveled long distances begging for food. Famine was prevalent in north and southwest Ireland, following the failure of wheat, oat, and potato harvests. In Germany, the crisis was severe; food prices rose sharply. With the cause of the problems unknown, people demonstrated in front of grain markets and bakeries, and later riots, arson, and looting took place in many European cities. It was the worst famine of 19th-century mainland Europe.[16][17] The long-running Central England temperature record reported the 11th coldest year on records since 1659, as well as the 3rd coldest summer and the coldest July on record.[18]

The effects were widespread and lasted beyond the winter. In western Switzerland, the summers of 1816 and 1817 were so cold that an ice dam formed below a tongue of the Giétro Glacier high in the Val de Bagnes. Despite engineer Ignaz Venetz's efforts to drain the growing lake, the ice dam collapsed catastrophically in June 1818, killing 40 people.[19]

In the spring and summer of 1816, a persistent "dry fog" was observed in parts of the eastern United States. The fog reddened and dimmed the sunlight, such that sunspots were visible to the naked eye. Neither wind nor rainfall dispersed the "fog". It has been characterized as a "stratospheric sulfate aerosol veil".[20]

The weather was not in itself a hardship for those accustomed to long winters. The real problem lay in the weather's effect on crops and thus on the supply of food and firewood. At higher elevations, where farming was problematic in good years, the cooler climate did not quite support agriculture. In May 1816,[1] frost killed off most crops in the higher elevations of Massachusetts, New Hampshire, and Vermont, as well as upstate New York. On June 6, snow fell in Albany, New York, and Dennysville, Maine.[16] In Cape May, New Jersey, frost was reported five nights in a row in late June, causing extensive crop damage.[21]

Many commented on the phenomenon. Sarah Snell Bryant, of Cummington, Massachusetts, wrote in her diary, "Weather backward."[22]

At the Church Family of Shakers near New Lebanon, New York, Nicholas Bennet wrote in May 1816, "all was froze" and the hills were "barren like winter". Temperatures went below freezing almost every day in May. The ground froze on June 9. On June 12, the Shakers had to replant crops destroyed by the cold. On July 7, it was so cold, everything had stopped growing. The Berkshire Hills had frost again on August 23, as did much of the upper northeast.[23]

A Massachusetts historian summed up the disaster:

Severe frosts occurred every month; June 7th and 8th snow fell, and it was so cold that crops were cut down, even freezing the roots ... In the early Autumn when corn was in the milk it was so thoroughly frozen that it never ripened and was scarcely worth harvesting. Breadstuffs were scarce and prices high and the poorer class of people were often in straits for want of food. It must be remembered that the granaries of the great west had not then been opened to us by railroad communication, and people were obliged to rely upon their own resources or upon others in their immediate locality.[24]

In July and August, lake and river ice was observed as far south as northwestern Pennsylvania. Frost was reported as far south as Virginia on August 20 and 21.[25] Rapid, dramatic temperature swings were common, with temperatures sometimes reverting from normal or above-normal summer temperatures as high as 95 °F (35 °C) to near-freezing within hours. Thomas Jefferson, retired from the presidency and farming at Monticello, sustained crop failures that sent him further into debt. On September 13, a Virginia newspaper reported that corn crops would be one half to two-thirds short and lamented that "the cold as well as the drought has nipt the buds of hope".[26] A Norfolk, Virginia newspaper reported:

It is now the middle of July, and we have not yet had what could properly be called summer. Easterly winds have prevailed for nearly three months past ... the sun during that time has generally been obscured and the sky overcast with clouds; the air has been damp and uncomfortable, and frequently so chilling as to render the fireside a desirable retreat.[27]

Regional farmers did succeed in bringing some crops to maturity, but corn and other grain prices rose dramatically. The price of oats, for example, rose from 12¢ per bushel ($3.40/m³) in 1815 (equal to $1.68 today) to 92¢ per bushel ($26/m³) in 1816 ($13.86 today). Crop failures were aggravated by an inadequate transportation network: with few roads or navigable inland waterways and no railroads, it was expensive to import food.[28]

High levels of tephra in the atmosphere led to unusually spectacular sunsets during this period, a feature celebrated in the paintings of J. M. W. Turner. This may have given rise to the yellow tinge predominant in his paintings such as Chichester Canal circa 1828. Similar phenomena were observed after the 1883 eruption of Krakatoa, and on the West Coast of the United States following the 1991 eruption of Mount Pinatubo in the Philippines.

The lack of oats to feed horses may have inspired the German inventor Karl Drais to research new ways of horseless transportation, which led to the invention of the draisine or velocipede. This was the ancestor of the modern bicycle and a step toward mechanized personal transport.[30]

The crop failures of the "Year without a Summer" may have helped shape the settling of the "American Heartland", as many thousands of people (particularly farm families who were wiped out by the event) left New England for western New York and the Northwest Territory in search of a more hospitable climate, richer soil, and better growing conditions.[31] Indiana became a state in December 1816 and Illinois two years later. British historian Lawrence Goldman has suggested that this migration into the Burned-over district of New York was responsible for the centering of the anti-slavery movement in that region.[32]

Chichester Canal by J. M. W. Turner (1828)

According to historian L. D. Stillwell, Vermont alone experienced a decrease in population of between 10,000 and 15,000, erasing seven previous years of population growth.[5] Among those who left Vermont were the family of Joseph Smith, who moved from Norwich, Vermont (though he was born in Sharon, Vermont) to Palmyra, New York.[33] This move precipitated the series of events that culminated in the publication of the Book of Mormon and the founding of the Church of Jesus Christ of Latter-day Saints.[7]

In June 1816, "incessant rainfall" during that "wet, ungenial summer" forced Mary Shelley[34], Percy Bysshe Shelley, Lord Byron and John William Polidori, and their friends to stay indoors at Villa Diodati overlooking Lake Geneva for much of their Swiss holiday.[32][35][36] They decided to have a contest to see who could write the scariest story, leading Shelley to write Frankenstein, or The Modern Prometheus and Lord Byron to write "A Fragment", which Polidori later used as inspiration for The Vampyre[37] – a precursor to Dracula. In addition, Lord Byron was inspired to write the poem "Darkness", by a single day when "the fowls all went to roost at noon and candles had to be lit as at midnight".[32]

Justus von Liebig, a chemist who had experienced the famine as a child in Darmstadt, later studied plant nutrition and introduced mineral fertilizers.