(ORDO NEWS) — Scientists have studied the migrations of Antarctic icebergs over the past one and a half million years and have found that it is their trajectories that can determine whether a new great glaciation of the Earth begins.
The history of the Earth has repeatedly repeated periods of long-term cooling of the climate, which led to the formation of new ice sheets. So, the last ice age ended 12 thousand years ago, and now the Earth is going through an interglacial period.
Until now, scientists have remained a mystery how the position of the Earth’s orbit relative to the Sun affects the heating of the earth’s surface. They did not understand what changes in the orbit could provoke large-scale climate changes leading to glaciation. A large international group of researchers has proposed a different mechanism that can influence the climate.
It is known that icebergs break off from the Antarctic ice sheet and move north into the Atlantic Ocean. They melt in its warm waters, leading to its desalination. At the same time, Antarctic waters are becoming saltier (after all, icebergs are leaving). This process changes the circulation of water flows in the oceans, which can accelerate the absorption of atmospheric CO2 by the ocean. As a result, the greenhouse effect decreases, which, recall, leads to a warming up of the atmosphere. And that’s exactly what it looks like … the beginning of the ice age.
To come to these conclusions, scientists have reconstructed the state of the oceans of the past, using, among other things, samples of ancient rocks that settled to the bottom as drifting icebergs melted. These samples were taken from the waters of South Africa as part of the World Ocean Exploration Program.
Researchers were able to trace the history of the movement of icebergs to these places over one and a half million years. By the way, such an impressive time period is rarely studied within the framework of one scientific study.
Scientists analyzed the chemical composition of the collected samples and also used a climate model to test their hypothesis about the movement of fresh water from Antarctica north to the Atlantic Ocean.
“We found that similar processes can be seen in every ice age that has occurred in the past 1.6 million years. This suggests that the [Southern] Ocean surrounding Antarctica plays an important role in shaping the Earth’s climate. Scientists have long suspected this, but we have only now been able to demonstrate this, “said lead study author and PhD student at Cardiff University, Aiden Starr.
However, human activities can greatly affect the concentration of CO2 and change the dynamics of the mechanism described by scientists. Due to the greenhouse effect, the Southern Ocean can warm to such an extent that icebergs will melt right in it, which means that all subsequent processes will be “canceled”. What will ultimately await our planet is not clear.
The study was published in the prestigious scientific journal Nature in January 2021.
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