The eruption of Mount Tambora in Indonesia in 1815 plunged the Earth into a prolonged period of cold climate, leading to severe consequences.
Volcanic eruptions can change the Earth’s climate. During major eruptions, vast quantities of volcanic ash released into the stratosphere form a veil that blocks sunlight and heat from reaching the Earth. Additionally, volcanic gases such as sulfur dioxide have a cooling effect, in contrast to greenhouse gases like carbon dioxide.
The caldera of Mount Tambora. (Photo: Amusing Planet).
When it erupted in 1815 on Sumbawa Island in present-day Indonesia, Mount Tambora expelled an estimated 120 million tons of sulfur dioxide 40 kilometers into the atmosphere. The sulfur dioxide transformed into a fine sulfuric acid aerosol, enveloping much of the Earth within weeks. This aerosol layer reflected solar radiation back into space, creating a global cooling effect. The following year became one of the coldest in history.
The Tambora eruption was the most powerful volcanic eruption ever witnessed by humanity. The eruption began on April 5, 1815, and lasted for the next four months. During that time, the volcano expelled more than 150 cubic kilometers of rock and magma, creating a caldera with a diameter of 7 kilometers. The mountain, originally standing at 4,300 meters, collapsed to just 2,850 meters.
The aftermath of the eruption was devastating. Pumice and ash fell over the region for weeks, spreading as far as South Sumatra and Borneo, 1,300 kilometers away. The entire island was covered in ash and volcanic debris up to one meter deep, destroying homes, crops, and uprooting trees. Pumice fell into the sea, forming rafts up to 5 kilometers wide. These rafts drifted offshore, colliding with British ships 3,600 kilometers away. Fine ash particles lingered in the atmosphere for years, creating vivid sunsets and twilights that could be seen as far away as London.
The direct consequences of the eruption included famine due to destroyed crops, along with various diseases, particularly diarrhea from contaminated water. The famine was so severe that people in Sumbawa were forced to eat dry leaves and toxic wild roots. Many resorted to selling their children for rice. Approximately 48,000 people in Sumbawa and 44,000 in Lombok perished. Tens of thousands migrated to Java, Bali, and South Sulawesi to escape the famine.
The effects of the eruption were not limited to Indonesia. Unseasonably cold weather killed trees, rice, and livestock in northern regions such as China and Tibet. Flooding devastated any remaining crops. In Taiwan, a tropical climate area, snow fell in several cities. In Europe, low temperatures and heavy rains led to poor harvests across the continent, causing severe famines in Ireland and Wales. Scarlet fever outbreaks occurred in many parts of Europe, including Ireland, Italy, Switzerland, and Scotland, exacerbated by malnutrition resulting from the year without a summer.
Temperatures dropped sharply in North America, especially in the northeastern United States and Canada. During spring and summer, a prolonged dry fog obscured sunlight, making it possible to see dark streaks of the sun with the naked eye. Frost and snow fell in high areas of New Hampshire, Maine, Vermont, and northern New York in mid-summer. The cold weather destroyed much of the crops in North America, leading to soaring prices. In Canada, Quebec faced shortages of bread and milk.
Today, scientists are certain that global weather phenomena, the cold climate, and crop failures were direct results of the Tambora eruption, a connection that took decades to unravel. The first scientist to establish a link between volcanic eruptions and cooler temperatures on Earth was Benjamin Franklin in 1783. Between 1914 and 1920, researcher W.J. Humphreys at the U.S. Weather Bureau indicated a relationship between the poor weather of 1816 and the eruption of Mount Tambora the previous year.
