The eruption of Indonesia’s Tambora volcano, the largest eruption in history at that time, killed an estimated ninety-two thousand people and vented enough material into the stratosphere to cause global cooling and unusually cold summers as far as Europe and North America into the following year.
When the Indonesian volcano Tambora erupted at full force in April, 1815, it spewed about 150 cubic kilometers (36 cubic miles) of ash into the stratosphere. It also killed an estimated ninety-two thousand people on the islands of Sumbawa and Lombok. About ten thousand people died during the great eruption, and the remaining deaths resulted from disease and starvation following the cataclysm. The eruption was isolated and far from Western trade routes, ensuring that information about the event would be difficult to come by. However, Sir Stamford Raffles, the British lieutenant governor of Java at the time of the eruption, collected as many accounts of the eruption as possible, providing at least some information on the conditions following the blast.
Tambora occupies the elliptical Sanggar Peninsula on the northwest coast of the island of Sumbawa. Geologically, Sumbawa seems to have been originally an island that eventually connected to the mainland as the volcano grew. Pre-eruption descriptions of the volcano indicate that it may have been as high as 4,000 meters (more than 13,000 feet), which would have made it the highest peak in the East Indies. In modern Indonesia, only peaks in New Guinea are taller than this estimate. The volcano had not erupted in historic times, and later investigations indicate more than five thousand years may have passed since its last eruption. Little evidence exists for highly explosive eruptions before 1815, suggesting that the volcano had only recently entered a new phase in its life cycle.
Mild eruptions began at least one year, and possibly as long as three years, before the great eruption of 1815. Smaller eruptions became more violent on April 5, 1815, and they continued until the main event on April 10. On April 6, explosions reportedly were heard as far as 1,400 kilometers (900 miles) away. The main eruption started when a column of ash and hot gases rose to at least 30 kilometers (nearly 100,000 feet) altitude for about one hour. As the gas pressure beneath the volcano lessened, the column collapsed, sending pyroclastic flows of incandescent gases, ash, and pumice fragments down the mountain in all directions. On April 11 explosions were heard as far away as 2,600 kilometers (1,600 miles). The main phase of the eruption lasted only about twenty-four hours, although ash continued to fall in Java for several days and smaller eruptions continued until July. During the great eruption, the volcano lost more than 1,000 meters (3,000 feet) of its summit, which collapsed inward to form a deep basin, or caldera. It was not until 1847 that Heinrich Zollinger,
High-altitude ejecta from Tambora consisted of ash particles, or finely pulverized rock particles, and microscopic sulfuric acid droplets, or aerosols, which are much more effective than ash at intercepting sunlight and modifying climate. From June 28 to July 2, and again from September 3 to October 7, brilliantly colored sunsets were seen in London. Observers specifically noted that these sunsets differed from normal sunsets because the colors extended higher in the sky and lasted longer than usual. Many reported unusual conditions, including sunspots that were visible to the unaided eye, days where the sun was red well above the horizon, and dimmed stars near the horizon. Reports of unusual atmospheric dimming, or extinction, persisted into 1817. The eclipse
Ice cores later collected in Antarctica
Pre-industrial age skies were much clearer than those of the present time. Human activities generate enough dust to reduce average visibility to less than half of what it was in pre-industrial times. Although modern humans take little notice of hazy conditions, haze that was not connected to humid weather conditions was highly unusual in the time before industrialization, and accounts of “dry fog” have proven to be valuable indicators of high altitude volcanic particles. During the year 1816, there were persistent dry fogs over much of the northeastern United States. The same year, however, became notorious for other climatic effects as well. Unusually cold weather in North America and Europe caused 1816 to be known as the “year without a summer.”
Contemporary newspapers, letters, and diaries commented on the late spring of 1816. In early June, snow fell across much of northern New England
Tambora in Modern Indonesia
The principal recipients of the wrath of severe summer weather were corn and hay. Many newspaper reports of the time expressed more concern over the availability of fodder for livestock than over the weather’s direct effect on people. The crop failure of 1816 meant not only food and fodder shortages but also lack of seed to plant in 1817. Countless farmers left Vermont
In western Europe
There are debates, however, about whether or not Tambora’s eruption had any role in the global
During the early twentieth century, American physicist and meteorologist William J. Humphreys
Tambora’s great eruption marks one of the clearest and even most recent examples of how a volcano affects global climates. Conditions similar to those from Tambora, especially dry fogs and unusual cold weather, were found in other records and were used to infer the dates of large eruptions in areas that were either unexplored or without written records. Tambora is also a benchmark for computer modeling of the effects of large eruptions, and it was widely cited as a natural analogue for the climatic effects of a so-called nuclear winter that could follow a global nuclear war.
Tambora’s eruption also shows how difficult it is to infer environmental cause and effect. Although 1816 was the coldest summer on record in some places around the world, that year does not appear, in other locations, to be dramatically different from earlier cold years without summer snowfalls. The ambiguities in interpreting the effects of the largest eruption in historic times illustrate how difficult it can be to establish cause and effect for more subtle climatic changes.
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Botkin, Daniel B., ed. Forces of Change: A New View of Nature, Washington, D.C.: National Geographic Society, 2000. Prominent scientists offer perspectives on global change and the processes that shape it, including the role of volcanic eruptions. -
Francis, Peter. Volcanoes: A Planetary Perspective. New York: Oxford University Press, 1993. Presents a global history of volcanoes and volcanic eruptions. -
Self, S., M. R. Rampino, M. S. Newton, and J. A. Wolff. “Volcanological Study of the Great Tambora Eruption of 1815.” Geology 12 (1989): 659-663. A summary of the eruption of 1815, describing ash layers and the summit collapse. -
Stommel, Henry, and Elizabeth Stommel. Volcano Weather: The Story of 1816, the Year Without a Summer. Newport, R.I.: Seven Seas Press, 1983. Discussion of the climatic effects of Tambora in the year following the eruption, with emphasis on New England. Includes many newspaper and diary excerpts. -
Stothers, Richard B. “The Great Tambora Eruption of 1815 and Its Aftermath.” Science 224 (June, 1984): 1191-1198. An analysis of worldwide climatic data, with lengthy discussions of the observational evidence for global stratospheric aerosols. -
Wade, Nicholas. The “New York Times” Book of Natural Disasters. Guilford, Conn.: Lyons Press, 2001. New York Times science reporters examine natural disasters, including the effects of ancient, recent, and future volcanic eruptions.
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