The last ice age ended about 13 thousand years ago due to a series of powerful volcanic eruptions in Antarctica, which melted part of its ice, destroyed the ozone layer and caused global warming, according to an article published in the journal PNAS.
“Our measurements show that the most powerful eruptions of the Takahe volcano on the Antarctic Peninsula, which emitted huge amounts of chlorine and other halogens into the atmosphere, coincide in time with the beginning of the fastest and sharpest warming in the entire history of the Earth's southern hemisphere. At the same time, greenhouse gas concentrations began to rise across the planet,”said Joseph McConnell of the Institute for Desert Research in Reno, USA.
The last ice age in the history of the Earth, as geologists today believe, began about 2.6 million years ago. Its main feature is that the area of glaciation and the temperature of the Earth's surface throughout its entire length were not constant - the glaciers advanced and receded every 40 and 100 thousand years, and these episodes were accompanied by sharp cooling and warming. The last period of warming began about 13 thousand years ago and continues to this day.
These cycles of glaciations and "thaws", as many scientists today believe, are primarily associated with the so-called Milankovitch cycles - the "rocking" of the Earth's orbit, changing how much heat is received by the poles and temperate latitudes. Other geologists and climatologists believe that, in fact, these abrupt climate changes are associated not with "space", but completely terrestrial factors, such as restructuring of the "conveyor" of currents in the oceans or an increase or decrease in the proportion of CO2 in the atmosphere.
McConnell and his colleagues figured out what caused the Earth to thaw the last time by studying ice samples extracted from glaciers in western Antarctica, about 400 kilometers from the ocean. These ices, whose thickness is about three kilometers, have been forming over the past 68 thousand years, which allowed scientists to study how the climate of the continent has changed over this time, analyzing the chemical composition of air inclusions in their thickness.
Studying these ice deposits, American climatologists noticed something extremely unusual - in those layers that were formed about 17.5-17 thousand years ago, they recorded an unusually large number of atoms of bromine, chlorine and other halogens, as well as a number of other substances atypical for ice. including heavy metals and sulfur.
Rare earth and heavy metals can get into the air in such quantities only in one case - during very strong and prolonged volcanic eruptions. Their source in this case, as the calculations of scientists show, was the Takahe volcano, located 350 kilometers from the point where McConnell and his colleagues collected ice samples.
These eruptions, according to climatologists, lasted for about 190 years, as a result of which not only a huge amount of greenhouse gases got into the atmosphere, but also halogens, actively destroying the ozone layer. As a result, not only global warming began, but an ozone hole also appeared, which dramatically changed the nature of the movement of winds over the Antarctic and the southern part of the Atlantic and Indian Ocean.
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These changes, in turn, led to large-scale restructuring of currents, which led to the fact that the Earth's climate changed irreversibly, emerging from the endless cycle of glaciations and interglacial periods. It is possible that the planet's climate could change in a similar way in more ancient historical eras, scientists conclude.