2024-02-16 09:25:00
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This is what the Earth might have looked like around 700 million years ago. © NASA
The Sturtian Ice Age held the Earth in its grip for 57 million years. Researchers have now discovered why it lasted so long.
Sydney – About 700 million years ago, the Earth was almost completely covered in ice. For 57 million years, the so-called Sturtian Ice Age held the planet in its icy grip. This didn’t bother people or animals back then, because there weren’t any yet. Nevertheless, this time is particularly exciting for research. “Imagine if the Earth was almost completely frozen over,” says Adriana Dutkiewicz, a scientist at the University of Sydney. “That’s exactly what happened about 700 million years ago: the planet was covered in ice from the poles to the equator and temperatures dropped.”
The question of what caused this extreme ice age, known as the Sturtian Ice Age, and why it lasted an incredible 57 million years has long been a mystery to science. “Various reasons have been proposed for the start and end of this extreme ice age, but the most puzzling is why it lasted 57 million years – a period of time that is difficult for us humans to imagine,” says Dutkiewicz.
Why the Earth was an icy ball for so long
But now Dutkiewicz’s research team seems to have found an answer to this puzzle. “We now believe we have cracked the puzzle,” says Dutkiewicz, adding: “Historically low volcanic carbon dioxide emissions, facilitated by the weathering of a large pile of volcanic rock in what is now Canada; a process that absorbs atmospheric carbon dioxide.” The study was in the specialist journal Geology published.
The research group used a model that depicts the development of continents and oceans after the breakup of the ancient supercontinent Rodina. She combined this with a computer model that calculates CO₂ outgassing from underwater volcanoes along mid-ocean ridges. The team found that the start of the Sturtian Ice Age coincided exactly with a historic low in volcanic CO₂ emissions. CO₂ emissions remained relatively low throughout the Ice Age.
Volcanoes released less CO₂ – and the earth cooled
Dietmar Müller, a co-author of the study, explains in a notice: “Geology determined the climate at that time. We believe the Sturtian Ice Age was triggered by a double bang effect: a plate tectonic realignment brought volcanic degassing to a minimum, while at the same time a continental volcanic province in Canada began to erode, consuming atmospheric CO₂ in the process.”
The result was a drastic decline in carbon dioxide in the atmosphere. “Atmospheric CO₂ levels fell to a level at which icing sets in – which, according to our estimates, is below 200 parts per million, less than half of today’s value,” explains Müller.
Earth will get hotter rather than becoming an ice ball again
Despite the fact that Earth is currently on a course with fewer volcanic CO₂ emissions, scientists are not worried that the planet will return to an icy ball any time soon. Instead, the focus is on the effects of global warming, such as melting glaciers, rising sea levels and increasing temperatures. A recent study recently showed that the Earth could evolve into the supercontinent Pangea Ultima in the next 250 million years. The huge landmass is said to be so hot that mammals could become extinct.
Dutkiewicz emphasizes the importance of understanding geological climate changes and warns about the speed of human-caused climate change: “Whatever the future holds, it is important to know that geological climate changes such as those studied here are extremely slow. According to NASA, human-caused climate change is occurring ten times faster than we have previously experienced.” (tab)
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