Scientists have uncovered the mystery of sudden thaws in the ice age

© Illustration RIA Novosti . Alina Polarisavenue figured out what was bound abrupt periods of warming to ice ageScientists have uncovered the mystery of sudden thaws in the ice age© Illustration RIA Novosti . Alina Polyanina

Mysterious episodes of warming during the ice age, when temperatures in the North the Land rises sharply to 15 degrees, have been associated with fluctuations in CO2 concentration in the atmosphere and changes in the movement of currents in the Atlantic, say scientists, who published an article in the journal Nature Geoscience.

«This discovery does not mean that something similar will happen in the future as a result of rising CO2 levels, because now the boundaries between different climatic regimes not as during the glacial period. However, our work shows that very abrupt climate change can occur under the action very smooth changes,» says Gerrit Lohmann (Gerrit Lohmann) from the Alfred Wegener Institute in Bremerhaven (Germany).

The last glacial period in Earth’s history, how geologists now believe, began about 2.6 million years ago and it continues to this day. Its main feature is that the area of glaciation and surface temperature of the Earth throughout its duration was not permanent – the glaciers came and receded every 40 and 100 thousand years, and these episodes were accompanied by a sharp cooling and warming.

These cycles of glaciations and «thaws,» as many scientists now believe, primarily associated with the so-called Milankovitch cycles – «wobble» of the Earth’s orbit that change how much heat is getting poles and temperate latitudes. Other geologists and climatologists believe that in fact these abrupt climate changes are not associated with «space», but it is earthly factors such as the restructuring of the «conveyor belt» of currents in the oceans or the increase or decrease of the share of CO2 in the atmosphere.

Lohmann and his colleagues found new arguments in favor of the second group of theories, creating a computer model of the Earth during the glacial period and tracing how varied the work of its climate control systems when raising or lowering the CO2 level.

As shown by these calculations, even a relatively small and very gradual changes in the concentration of carbon dioxide in the air can lead to very sharp and almost instantaneous changes of climate.

For example, higher percentages of CO2 in the atmosphere from the level of 180 ppm, the minimum concentration of carbon dioxide during the ice age, up to a value of 220 ppm, which is approximately equal to half of the current fraction of carbon dioxide in the air has led to two very serious consequences.

As a result, as they say scientists, there is the phenomenon of El niño, transporting heat and water from the tropical Pacific ocean in the temperate latitudes, and increased Golfstrim and related currents in the North Atlantic. Due to this temperature in the polar latitudes grew dramatically, increasing in some regions, 15 degrees Celsius, which led to a very rapid disappearance of ice caps and significant reductions on land.

If the CO2 concentration fell below this level, then the climate soon returned to its previous mode – flow slowed, the heat transfer stopped and the glaciers back to their old borders. Why does it happen and how did this climate swings, scientists do not yet know but plan to find out, comparing the results of their calculations and data on the real climate fluctuations in the last million years.

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