Identifying the 'culprit' that cooled the Earth in 1831

Simushir Island in the Pacific Northwest is the source of the 1831 eruption.

Mysterious eruption

The 1831 eruption was one of the most powerful eruptions of the 19th century, spewing massive amounts of sulfur dioxide into the stratosphere, causing the average annual temperature in the Northern Hemisphere to drop by about 1 degree Celsius. This event occurred during the late stages of the Little Ice Age, one of the coldest periods on Earth in the last 10,000 years.

Although the year of this historical eruption was known, the location of the volcano was not. Researchers recently solved that puzzle by sampling ice cores in Greenland, looking back in time through the core layers to examine sulfur isotopes, ash particles, and tiny fragments of volcanic glass deposited between 1831 and 1834.

Using geochemistry, radiometric dating, and computer modeling to map particle trajectories, scientists linked the 1831 eruption to a volcano on an island in the Pacific Northwest, they reported on December 30, 2024, in the journal Proceedings of the National Academy of Sciences.

According to the analysis, the mysterious volcano is Zavaritskii, located on Simushir Island, part of the Kuril Islands. Before scientists discovered this, the last known eruption of Zavaritskii was in 800 BC.

“For many volcanoes on Earth, especially those in remote areas, we understand very little about their eruption history. Zavaritskii is located on an extremely remote island between Japan and Russia. No one lives there, and historical records are limited to a few logs from ships that passed by these islands every few years,” said Dr. William Hutchison, lead author of the study and principal investigator in the Department of Earth and Environmental Sciences at the University of St. Andrews in the UK.

With very little information about Zavaritskii's activity in the 19th century, no one previously suspected that it could be a candidate for the 1831 eruption. Instead, researchers considered volcanoes closer to the equator, such as Babuyan Claro in the Philippines.

“This eruption had an impact on the global climate but was mistakenly attributed to a tropical volcano for a long time. Research now shows the eruption occurred in the Kuril Islands, not in the tropics,” said Dr. Stefan Brönnimann, head of the climatology group at the University of Bern in Switzerland.

Studies of Greenland ice cores have revealed that, in 1831, the amount of sulfur dust—a sign of volcanic activity—in Greenland was approximately 6.5 times greater than in Antarctica. Researchers report that this finding suggests the origin was a large eruption from a mid-latitude volcano in the Northern Hemisphere.

The research team also chemically analyzed ash and fragments of volcanic glass no longer than 0.02 mm. When the scientists compared their results to geochemical datasets from volcanic regions, the most consistent findings were in Japan and the Kuril Islands. Volcanic eruptions in Japan in the 19th century were well documented, and there were no records of a major eruption in 1831. But colleagues who had previously visited volcanoes in the Kuril Islands provided samples that helped the researchers find a geochemical match with the Zavaritskii crater.

Furthermore, according to Dr. Hutchison, volumetric and sulfur isotope analysis of the crater suggests it formed after a major eruption between 1700 and 1900, making Zavaritskii a "leading candidate" for the mysterious 1831 eruption.

The 1831 eruption occurred at the Zavaritskii volcano on Simushir Island. The eruption created a crater 1.87 miles wide, revealing layers of red, black, and white formed from past volcanic deposits.

The End of the Little Ice Age

Along with Zavaritskii, three other volcanoes erupted between 1808 and 1835. They marked the end of the Little Ice Age, an unusual climate phenomenon that lasted from the early 1400s to around 1850. During this time, annual temperatures in the Northern Hemisphere decreased by an average of 0.6 degrees Celsius. In some places, temperatures were 2 degrees Celsius cooler than normal, and the cool conditions lasted for decades.

Two of the four eruptions had been previously identified: Mount Tambora in Indonesia erupted in 1815 and Cosegüina in Nicaragua in 1835. The volcano that produced the 1808/1809 eruption remains unknown. The study authors reported that the addition of Zavaritskii highlights the possibility that volcanoes in the Kuril Islands could disrupt the Earth's climate.

Following the 1831 eruption, colder and drier conditions emerged in the Northern Hemisphere. Reports of famine and hardship spread rapidly afterward, as famine spread across India, Japan, and Europe, affecting millions of people.

Hutchison suggests that the cooling of the volcanic climate appears to have led to crop failures and famine. A focus of ongoing research is understanding the extent to which these famines were caused by the cooling of the volcanic climate or by other socio -political factors.

"By providing long-lost information about 19th-century volcanoes that cooled the Earth's climate, this research may further strengthen our belief in the role of volcanic eruptions during the late stages of the Little Ice Age," said Brönnimann.

According to Hutchison, like Zavaritskii, many volcanoes around the world are located in isolated and poorly monitored areas, making it difficult to predict the timing and location of the next major eruption. If there is one lesson to be learned from the 1831 eruption, it is that volcanic activity in remote locations can have devastating global consequences.

"We really lack coordination within the international community to act together when the next major eruption occurs. That's something we need to think about as scientists and as a society," Hutchison said.

Source: https://daidoanket.vn/xac-dinh-thu-pham-lam-mat-trai-dat-vao-nam-1831-10297829.html