Identified, almost two centuries later, the volcanic eruption that caused the ‘ice summer’ of 1831

The phenomenon was so famous that even the famous composer Félix Mendelson wrote down his impressions during the trip he made to the Alps that unusual summer: “desolate weather, it has rained again all night and all morning, it is as cold as in winter, there is already deep snow on the nearest hills…”

A scientific mystery

At that time, it was difficult to identify the causes of this brutal and sudden climate change, but today, the presence of a large amount of sulfur trapped in the ice of Greenland and Antarctica clearly tells us that it was due to a massive volcanic eruption. proportions. Something that, by the way, also explains the blue color of the Sun, since when the ash particles emitted by the volcano are very fine and are uniformly distributed in the atmosphere, they can disperse the red and yellow wavelengths, making the Sun, blue and green tones predominate.

The culprit of that icy summer was, therefore, a volcano. But which one? The mystery, which has baffled scientists for almost two centuries, has just been solved by a team of experts from the Scottish university of St Andrews.

Under the direction of Will Hutchinson, scientists analyzed ice core strata from 1831 and identified a “perfect fingerprint match” in the ash deposits. The study has just been published in ‘Proceedings of the National Academy of Sciences‘.

“Only in recent years,” explains Hutchison, “have we developed the ability to extract microscopic fragments of ash from polar ice cores and perform detailed chemical analyzes on them. “These fragments are incredibly tiny, about one-tenth the diameter of a human hair.”

After their analysis, Hutchinson and his team managed to precisely date and relate those tiny fragments of ash found in the ice with those of the Zavaritskii volcano, on the remote and uninhabited island of Simushir, part of the Kuril Islands, a territory disputed between Russia. and Japan.

Currently controlled by Russia, the Kurils operate as a strategic military outpost. During the Cold War, in a plot reminiscent of a spy movie, the Soviets even used Simushir as a secret base for nuclear submarines, docking ships in a flooded volcanic crater.

eureka moment

“We analyze the chemistry of the ice with a very high temporal resolution,” says Hutchinson. This allowed us to determine the precise time of the eruption, spring-summer 1831, confirm that it was highly explosive, and then extract the small ash fragments. “Finding the match took a long time and required extensive collaboration with colleagues in Japan and Russia, who provided us with samples collected from these remote volcanoes decades ago.”

«When the time came in the laboratory to analyze the two ashes together, that of the volcano and that of the ice cores – continues the researcher -, a true ‘eureka moment’ occurred. I couldn’t believe the numbers were identical. “After this, I spent a lot of time researching the age and size of the eruption in the Kuril records to really convince myself that the coincidence was real.” The work highlights the Kuril Islands as an understudied but extremely active volcanic region.

Despite being in such a remote location, the 1831 Zavaritskii eruption had a significant global impact on the climate and serious consequences for human populations. Identifying the sources of these mysterious eruptions of the past will allow scientists to map and monitor the regions of Earth most likely to produce volcanic events capable of altering the climate.

“There are many volcanoes like this,” Hutchinson concludes, “which highlights how difficult it will be to predict when or where the next large eruption might occur. “As scientists and as a society, we must consider how to coordinate an international response when the next major eruption like that of 1831 occurs.”