To cause the Little Ice Agethe period of intense cold that mainly affected Europe from the 16th to the 19th century approximatelythey would have been two almost simultaneous volcanic eruptions: that of Kuwae volcano in Vanuatuin Oceania, and of another volcano in the southern hemisphere which has yet to be identified. This is the recent discovery of a team of Korean and Russian researchers, published in the journal Communications Earth & Environment. Researchers have found evidence of this volcanic event, dating back to 1458-59 AD. and considered one of the more intense of the last millennium, in Antarctic ice. They have been found in ice cores ash particles And traces of sulfates released into the atmosphere during these eruptions. Their presence in the atmosphere prevented solar rays from reaching the Earth’s surface, resulting in a lowering of the average temperature for a very long time even at a great distance from the site of the eruption.
Evidence of eruptions in the Antarctic ice
It was long believed that the main cause of the Little Ice Age was one less solar activitycombined with a violent volcanic eruption. This study highlights that the predominant role in determining the drop in temperatures it was instead that of volcanoes. The researchers came to this conclusion by analyzing microscopic fragments of volcanic glass present in two ice cores taken in Antarctic ice sheet near the Vostok station and were trapped in a layer of ice whose age dates back to the volcanic event of 1458-59 AD. About half of the fragments have a chemical composition corresponding to that of the materials emitted by the Kuwae volcano in Vanuatuin Oceania. The rest of the particles have a similar composition to that of the ash emitted by the Reclus volcano in Chilewhich was suspected to be the second source, but the match is not exact. It has therefore been hypothesized that they come from a volcano located in the extratropical zone of the southern hemisphere but not yet identified: it could be found in the southern part of South America, in the sub-Antarctic islands or in the Antarctic Peninsula.
The sequence in which the particles are found in the ice and their sizes have made it possible to understand who they come from two almost simultaneous eruptions of volcanoes present at different latitudes. In fact, the larger particles are located below, which the wind cannot keep in suspension for long and which fall to the ground more quickly. These come from volcano of the extratropical zoneclosest to Antarctica. Above are the ashes finer than the equatorial volcano Kuwaewhich the wind managed to transport a greater distance and in a longer time.
What happened during the Little Ice Age in Europe
The large eruptions of the two volcanoes studied have released enormous quantities of ash and gasin particular sulfur dioxide (SO2), which, once it reached the stratosphere, reacted with the water vapor creating a layer made up of droplets of sulfuric acid (H2SO4). This layer is able to reflect the sun’s rays and thus prevented them from reaching the earth’s surface. Accordingly, the temperature it dropped on average by around 0.5 °Ca change that may seem small but which in reality has had serious consequences. THE’Europe has been particularly affected by the decrease in temperatures, which it has brought famines and epidemics. In reality, it was not a real ice age (the Last Ice Age in fact ended 11,700 years ago), but an interval of time characterized by a series of very cold periods alternating with milder periods.
The fact that the Little Ice Age lasted for centuries can be explained by hypothesizing, as computer simulations show, that the eruptions caused a chain reaction. Falling temperatures have caused Arctic sea ice to expand to lower latitudes, where melting has caused the weakening of ocean currents. As a result, the supply of warm water towards the North Pole decreased and therefore the expansion of sea ice increased: this mechanism fueled cooling in Europe.
Study is important not only for know climate variations better than in the past have affected our planet, but also for improve current climate models in order to develop forecasts that take into account the potential impact of volcanic eruptions at a global level.
