The eruption of Indonesia’s Mount Tambora in April 1815 altered the climate so dramatically that temperatures in some areas dropped as much as three degrees Celsius – and there’s no telling if or when a similar catastrophe could occur again.
During a volcanic eruption, millions of tons of ash, dust, and sulfur dioxide are spewed into the atmosphere. A strong enough eruption, like Tambora, blasts sulfur dioxide more than 10 miles above the surface of the earth, where it begins to form sulfate aerosols once it is exposed to water vapor in the atmosphere. Floating above the altitude of rain, these aerosols remain in the atmosphere reflecting sunlight and cooling the surface of the planet.
The resulting climate change following Tambora’s blast led to what is now known as “the year without a summer.” In 1816, millions of people from North America and Europe struggled with failed crops, near-famine food shortages, outbreaks of a number of diseases, and a widespread migration of people seeking a better home.
In the year after Tambora’s eruption, spring arrived as expected – but instead of the warm days of summer, temperatures began to drop and the cold weather returned. According to some reports, the sky seemed permanently overcast, blocking sunlight from reaching the surface of the earth.
In northern New England, people faced snow drifts of up to 20 inches in June. Crops failed across the country, and lambs and birds were dying from exposure. According to the New England Historical Society, people were resorting to killing raccoons and pigeons for meat. Europe also faced food riots and a typhus epidemic.
“We do not recollect the time when the drought has been so extensive, and general, not when there has been so cold a summer,” read a story published in New York State’s Albany Advertiser on October 6, 1816. “There have been hard frosts in every summer month, a fact that we have never known before. It has also been cold and dry in some parts of Europe, and very wet in other places in that quarter of the world.”
Fortunately, eruptions of this scale only occur on average once every 1,000 years, but the climate can still be impacted by similar events. While the eruption of Tambora is estimated to be about 100 times more powerful than Mount St. Helen in 1980, there are records of smaller eruptions causing global cooling for more than five years after the blast, including Krakatoa’s eruption in 1883 and Pinatubo’s in 1991.
Eruptions like this, about one-sixth the size of Tambora, occur about once every 100 years, and can cause global temperatures to drop by approximately one degree. Scientists have only recently started to investigate the link between volcanic activity and climate change. The link between eruptions and global cooling wasn’t confirmed until the 1960s and 1970s.
With temperatures around the world reaching record highs, a period of global cooling seems almost ideal, and scientists confirm that it would temporarily halt the effects of man-made climate change. However, as soon as the dust and ash settled out of the atmosphere, warming would pick right back up again – and the impact on populations around the world would last much longer.