Nearly two centuries after one of the most powerful eruptions of the 19th century caused global temperatures in the Northern Hemisphere to drop by around 1 degree Celsius, scientists have pinpointed the culprit: Zavaritskii volcano on Simushir Island in the northwest Pacific Ocean. The island is part of the Kuril Islands archipelago, a region disputed between Russia and Japan.
Published in the Proceedings of the National Academy of Sciences journal, the groundbreaking study links the historic 1831 eruption to Zavaritskii, which had previously been dormant since 800 BC. This revelation comes after decades of uncertainty, during which researchers knew the year of the eruption but struggled to locate the volcano responsible.
The breakthrough came from analyzing ice cores collected from Greenland. Researchers examined layers deposited between 1831 and 1834, searching for sulfur isotopes, volcanic glass shards, and ash grains. Advanced techniques, including radioactive dating, geochemistry, and computer modeling, allowed scientists to map the particles’ trajectories and trace them back to the remote volcanic island.
The 1831 eruption occurred during the tail end of the Little Ice Age, one of Earth’s coldest periods in the last 10,000 years. It significantly impacted the global climate, but historical records of Zavaritskii’s activity were nearly nonexistent. Dr. William Hutchison, a principal research fellow at the University of St. Andrews and the lead author of the study, highlighted the challenges in studying such remote volcanoes.
“For many of Earth’s volcanoes, particularly those in remote areas, we have a very poor understanding of their eruptive history,” Hutchison said. He explained that Zavaritskii’s isolated location, with no permanent residents and limited historical documentation, made it a less likely candidate for the 1831 eruption. Historical accounts were limited to occasional ship logs from vessels passing through the area.
Previously, researchers suspected other volcanoes, such as the Babuyan Claro volcano in the Philippines, as the source of the 1831 eruption due to their proximity to the equator. However, Zavaritskii’s identification shifts the focus to the northwest Pacific, shedding light on the significant impact of remote volcanic activity on Earth’s climate.
This discovery underscores the importance of studying even the most inaccessible volcanoes to better understand their potential role in shaping global climate patterns.