Mystery volcano from 1831 discovered: It caused global cooling

Mystery volcano from 1831 discovered: It caused global cooling

In 1831, an unknown volcano erupted so explosively that it cooled the Earth's climate. After almost 200 years of research, scientists have now identified the “secret volcano”.

The outbreak and its global impact

The eruption was one of the most powerful of the 19th century and released an enormous amount of sulfur dioxide into the stratosphere, causing average annual temperatures in the Northern Hemisphere to fall by about 1 degree Celsius. This event occurred during the final phase of the Little Ice Age, one of the coldest periods in Earth's history in the past 10,000 years.

Research and discovery of the secret volcano

Although the year of the historic eruption was known, the location of the volcano remained a mystery for a long time. Researchers were able to solve this mystery by examining ice cores in Greenland and analyzing the cores' layers to identify sulfur isotopes, ash grains and tiny volcanic glass shards deposited between 1831 and 1834.

Using geochemistry, radioactive dating and computer modeling, scientists were able to map the particle trajectories and link the 1831 eruption to an island volcano in the northwestern Pacific Ocean. They reported about it in a specialist journal Proceedings of the National Academy of Sciences.

The Zavaritskii volcano on Simushir

According to the analysis, the mysterious Zavaritskii (also called Zavaritsky) volcano on Simushir Island was part of the Kuril Islands archipelago, an area disputed between Russia and Japan. Before scientists' findings, the last known eruption of Zavaritskii was dated to 800 BC. Dated.

The challenge of volcanic monitoring

"For many of Earth's volcanoes, particularly in remote areas, we have a very weak understanding of their eruption history," said lead study author Dr. William Hutchison, a research fellow at the School of Earth and Environmental Sciences at the University of St. Andrews in the United Kingdom.

"Zavaritskii is located on an extremely remote island between Japan and Russia. No one lives there, and historical records are limited to a few diaries from ships that passed these islands every few years," Hutchison said in an email to CNN.

Scientific analysis and findings

Examination of Greenland ice cores showed that sulfur precipitation in Greenland in 1831 was about 6.5 times higher than in Antarctica. This suggested that the source was a major eruption from a mid-latitude volcano in the Northern Hemisphere.

The study team also chemically analyzed ash and particles of volcanic glass no larger than 0.02 millimeters. When the results were compared with geochemical data sets from volcanic regions, the best matches were found in Japan and the Kuril Islands. While eruptions in Japan were well documented in the 19th century, there was no record of a major eruption in 1831. But samples from colleagues who had previously visited volcanoes in the Kuril Islands led to the geochemical match with the Zavaritskii caldera.

Consequences and outlook

After the 1831 eruption, cooler and drier conditions occurred in the Northern Hemisphere, resulting in widespread hunger and hardship. Famines swept through India, Japan and Europe, affecting millions of people.

“It seems plausible that volcanic climate cooling led to crop failures and famines,” Hutchison said. “Current research focuses on the extent to which these famines were caused by volcanic climate cooling or other socio-political factors.”

Lessons from history

The findings from the research show that many volcanoes around the world are located in isolated areas and are poorly monitored, making it difficult to predict when and where the next major eruption might occur. If we can learn anything from the 1831 eruption, it is that volcanic activity in remote locations can have devastating global consequences for which humanity may be unprepared.

“We currently do not have a coordinated international community that could take action in the event of the next major outbreak,” Hutchison said. “Both scientists and society should work seriously on this.”

Mindy Weisberger is a science journalist and media producer whose work has appeared in Live Science, Scientific American, and How It Works, among others.