‘Mystery volcano’ that erupted and cooled Earth in 1831 has finally been identified

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An unknown volcano erupted so explosively in 1831 that it cooled Earth’s climate. Now, nearly 200 years later, scientists have identified the “mystery volcano.”

The eruption was one of the most powerful of the 19th century, spewing so much sulfur dioxide into the stratosphere that annual average temperatures in the Northern Hemisphere dropped by about one 1 degree Celsius (1.8 degrees Fahrenheit). The event took place during the last gasp of the Little Ice Age, one of the coldest periods on Earth in the past 10,000 years.

While the year of this historic eruption was known, the volcano’s location was not. Researchers recently solved that puzzle by sampling ice cores in Greenland, peering back in time through the cores’ layers to examine sulfur isotopes, grains of ash and tiny volcanic glass shards deposited between 1831 and 1834.

Mount Rainier volcano looms over Puyallup Valley, near Orting, Washington.

Related article Why Mount Rainier is the US volcano that troubles scientists most

Using geochemistry, radioactive dating and computer modeling to map particles’ trajectories, the scientists linked the 1831 eruption to an island volcano in the northwest Pacific Ocean, they reported Monday in the journal Proceedings of the National Academy of Sciences.

According to the analysis, the mystery volcano was Zavaritskii (also spelled Zavaritsky) on Simushir Island, part of the Kuril Islands archipelago, an area disputed by Russia and Japan. Before the scientists’ findings, Zavaritskii’s last known eruption was in 800 BC.

“For many of Earth’s volcanoes, particularly those in