The Year without a Summer
The unusual climatic aberrations of 1816 had the greatest effect on the Northeastern United States, the Canadian Maritimes, Newfoundland, and Northern Europe. Typically, the late spring and summer of the northeastern U.S. and southeastern Canada are relatively stable: temperatures (average of both day and night) average about 20–25 °C (68–77 °F), and rarely fall below 5 °C (41 °F). Summer snow is an extreme rarity.
In the spring and summer of 1816, a persistent dry fog was observed in the northeastern 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.
In May 1816, frost killed off most of the crops that had been planted, and on 4 June 1816, frosts were reported in Connecticut, and by the following day, most of New England was gripped by the cold front. On 6 June 1816, snow fell inAlbany, New York, and Dennysville, Maine. Nearly a foot (30 cm) of snow was observed in Quebec City in early June, with consequent additional loss of crops—most summer-growing plants have cell walls which rupture even in a mild frost. The result was regional malnutrition, starvation, epidemic, and increased mortality.
In July and August, lake and river ice were observed as far south as Pennsylvania. Rapid, dramatic temperature swings were common, with temperatures sometimes reverting from normal or above-normal summer temperatures as high as 35 °C (95 °F) to near-freezing within hours. Even though farmers south of New England did succeed in bringing some crops to maturity, maize and other grain prices rose dramatically. The staple food oats, for example, rose from 12¢ abushel ($3.40/m³) the previous year to 92¢ a bushel ($26/m³)—nearly eight times as much. Those areas suffering local crop failures had to deal with the lack of roads in the early 19th century, preventing any easy importation of bulky food stuffs.
Cool temperatures and heavy rains resulted in failed harvests in the British Isles as well. Families in Wales traveled long distances as refugees, begging for food. Famine was prevalent in north and southwest Ireland, following the failure ofwheat, oat and potato harvests. The crisis was severe in Germany, where food prices rose sharply. Due to the unknown cause of the problems, demonstrations in front of grain markets and bakeries, followed by riots, arson and looting, took place in many European cities. It was the worst famine of the 19th century,
In China, the cold weather killed trees, rice crops and even water buffalo, especially in northern China. Floods destroyed many remaining crops. Mount Tambora’s eruption disrupted China’s monsoon season, resulting in overwhelming floods in the Yangtze Valley in 1816. In India the delayed summer monsoon caused late torrential rains that aggravated the spread of cholera from a region near the River Ganges in Bengal to as far as Moscow.
In the ensuing bitter winter of 1817, when the thermometer dropped to -32 °C (-26°F), the waters of New York's Upper Bay froze deeply enough for horse-drawn sleighs to be driven across Buttermilk Channel from Brooklyn to Governors Island.
The effects were widespread and lasted beyond the winter. In eastern Switzerland, the summers of 1816 and 1817 were so cool that an ice dam formed below a tongue of the Giétro Glacier high in the Val de Bagnes; in spite of the efforts of the engineer Ignaz Venetz to drain the growing lake, the ice dam collapsed catastrophically in June 1818.
It is now generally thought that the aberrations occurred because of the 1815 (April 5–15) volcanic Mount Tambora eruption on the island of Sumbawa, Indonesia (then part of the Dutch East Indies). The eruption had a Volcanic Explosivity Index ranking of 7, a super-colossal event that ejected immense amounts of volcanic dust into the upper atmosphere. It was the world's largest eruption since the Hatepe eruption over 1,630 years earlier in AD 180. The fact that the 1815 eruption occurred during the middle of the Dalton Minimum (a period of unusually low solar activity) is also significant.
Other large volcanic eruptions (with VEI at least 4) during the same time frame are:
- 1812, La Soufrière on Saint Vincent in the Caribbean
- 1812, Awu on Sangihe Islands, Indonesia
- 1813, Suwanosejima on Ryukyu Islands, Japan
- 1814, Mayon in the Philippines
These other eruptions had already built up a substantial amount of atmospheric dust. As is common following a massive volcanic eruption, temperatures fell worldwide because less sunlight passed through the atmosphere.
As a result of the series of volcanic eruptions, crops in the above cited areas had been poor for several years; the final blow came in 1815 with the eruption of Tambora. In the United States, many historians cite the "Year Without a Summer" as a primary motivation for the western movement and rapid settlement of what is now western and central New York and the American Midwest. Many New Englanders were wiped out by the year, and tens of thousands struck out for the richer soil and better growing conditions of the Upper Midwest (then the Northwest Territory).
Europe, still recuperating from the Napoleonic Wars, suffered from food shortages. Food riots broke out in the United Kingdom and France and grain warehouses were looted. The violence was worst in landlocked Switzerland, where faminecaused the government to declare a national emergency. Huge storms, abnormal rainfall with floodings of the major rivers of Europe (including the Rhine) are attributed to the event, as was the frost setting in during August 1816. A majortyphus epidemic occurred in Ireland between 1816 and 1819, precipitated by the famine caused by "The Year Without a Summer". It is estimated that 100,000 Irish perished during this period. A BBC documentary using figures compiled in Switzerland estimated that fatality rates in 1816 were twice that of average years, giving an approximate European fatality total of 200,000 deaths.
The eruption of Tambora also caused Hungary to experience brown snow. Italy experienced something similar, with red snow falling throughout the year. The cause of this is believed to have been volcanic ash in the atmosphere.
In China, unusually low temperatures in summer and fall devastated rice production in Yunnan province in the southwest, resulting in widespread famine. Fort Shuangcheng, now in Heilongjiang province, reported fields disrupted by frost and conscripts deserting as a result. Summer snowfall was reported in various locations in Jiangxi and Anhui provinces, both in the south of the country. In Taiwan, which has a tropical climate, snow was reported in Hsinchu and Miaoli, while frost was reported in Changhua.
Historic cases of volcanic winter
The scales of recent winters are more modest but their effects can be significant.
The extreme weather events of 535–536 are most likely linked to a volcanic eruption.
The Great Famine of 1315–1317 in Europe may have been precipitated by a volcanic event, perhaps that of Kaharoa, New Zealand, which lasted about five years.
In 1452 or 1453, a cataclysmic eruption of the submarine volcano Kuwae caused worldwide disruptions.
In 1600, the Huaynaputina in Peru erupted. Tree ring studies show that 1601 was cold. Russia had its worst famine in 1601 to 1603. From 1600 to 1602, Switzerland, Latvia and Estonia had exceptionally cold winters. The wine harvest was late in 1601 in France, and in Peru and Germany wine production collapsed. Peach trees bloomed late in China, and Lake Suwa in Japan froze early.
A paper written by Benjamin Franklin in 1783 blamed the unusually cool summer of 1783 on volcanic dust coming from Iceland, where the eruption of Laki volcano had released enormous amounts ofsulfur dioxide, resulting in the death of much of the island's livestock and a catastrophic famine which killed a quarter of the population. Temperatures in the northern hemisphere dropped by about 1 °C in the year following the Laki eruption.
The 1815 eruption of Mount Tambora, a stratovolcano in Indonesia, occasioned mid-summer frosts in New York State and June snowfalls in New England and Newfoundland and Labrador in what came to be known as the "Year Without a Summer" of 1816.
In 1883, the explosion of Krakatoa (Krakatau) also created volcanic winter-like conditions. The next four years after the explosion were unusually cold, and the winter of 1887 to 1888 included powerful blizzards.. Record snowfalls were recorded worldwide.
Most recently, the 1991 explosion of Mount Pinatubo, another stratovolcano in the Philippines, cooled global temperatures for about 2–3 years.