The largest volcanic eruption of the last million years on Earth occurred 74,000 years ago in Indonesia. A new study links the eruption with global climate change in the time and its effect on early human populations.
The Toba volcano is located on the island of Sumatra in Indonesia, near the equator. The colossal eruption that happened 74,000 years ago has left a crater 50 kilometers in diameter. The eruption ejected 2500 cubic kilometers of lava, an amount equivalent to twice the size of Mount Everest.
The eruption was 5,000 times bigger than the 1980 Mount St. Helens in the United States. The eruption of Toba is the largest on Earth occurred in the last 2 million years.
The eruption raised huge clouds of ash and sulfuric acid into the atmosphere that reached the stratosphere, and then spread by air to the rest of the planet, to finally fall to the surface in the form of acid rain.
The team of Anders Svensson glaciologist, the Centre for Ice and Climate at the Niels Bohr Institute at Copenhagen University in Denmark, has now traced the vestiges of this acid rain in the ice sheets of Greenland and Antarctica. For some time, Svensson and colleagues have had an idea of how deep you could find traces of the eruption of Toba on the Greenland ice sheet, but found no ash, so it could not be sure. However, the same number of layers of acid resulting from that eruption now found in the ice in Greenland and Antarctica.
Researchers, after counting the annual layers between the peaks of acid present in ice cores of the two ice sheets, found a match. This means, as explained Svensson, who is now feasible to compare the Greenland ice cores in Antarctica with an annual precision, and thus combine knowledge about climate change at that time in the northern and southern hemispheres.
It has been much speculation about how big an eruption affected the climate. The giant clouds of sulfur particles that are released into the stratosphere in a cataclysm like that form a blanket that hinders the passage of solar radiation and this causes Earth to cool. But, to what extent and for how long? Previous studies with digital models indicated that this massive eruption could cause a cooling of up to 10 degrees in global temperature over decades. The new ice core analysis indicates, however, that the effect was felt mainly in the northern hemisphere, and that global cooling was brief.