Asteroid crash caused ice age on Earth - with unforeseen consequences

A collision of two asteroids far from Earth millions of years ago has had far-reaching consequences for our planet.

• There was an ice age on Earth 466 million years ago - what triggered it?
• Researchers assume that two asteroids were involved.
• The ice age had a serious impact on the earth - in a different way than expected.

466 million years ago - long before the first dinosaurs lived - there was an ice age on Earth. From the poles the water began to freeze slowly, different climatic zones were created on the previously climatically homogeneous earth. But what triggered this ice age?

Behind all of this is the collision of two asteroids far from Earth, in the asteroid belt between Mars and Jupiter, researchers now say. One of the two asteroids - scientists estimate that it had a diameter of around 150 kilometers - broke into small pieces. The fragments and the resulting dust came into the earth's atmosphere. "Normally, 40,000 tons of space dust fall to earth every year," explains Philipp Heck from the University of Chicago, who is one of the authors of a new study on the subject. After the asteroid * broke, this factor increased a thousand or even ten thousand times.

Asteroid crumbles to dust - and creates ice age on Earth

"Our theory is that over a period of at least two million years, these large amounts of dust have played a major role in climate change on Earth and have helped the Earth cool down," said Heck.

To arrive at this result, the researchers analyzed 466 million years old rock and compared it with micrometeorites, among other things. The research team looked for elements that are rare in earthly rocks, but are often found in stones from space - such as meteorites. Certain helium isotopes or rare metals are common in asteroids and prove that the dust comes from space.

Asteroid crash and ice age: the timing is right

At the time of the asteroid collision, an ice age had already started on Earth. The research team led by main author Birger Schmitz from the Swedish Lund University was able to prove by their research that the timing of the asteroid crash and the ice age match : the additional dust in the atmosphere is said to explain the ice age. The dust filtered the sunlight, darkened the earth and caused a global cooling.

In contrast to the asteroid impact 66 million years ago, which suddenly changed the Earth's climate and led to the extinction of the dinosaurs *, the dust gradually reached the Earth's atmosphere 466 million years ago. Over two million years, the earth slowly darkened - which also caused the cooling to take place slowly. This gave earthly life the chance to adapt to the new climatic conditions. Numerous new species emerged when living beings tried to survive under the new conditions.

Asteroid is to blame for climate change 466 million years ago

“The global cooling we have studied has taken millions of years. This is very different from the climate change triggered by the asteroid that killed the dinosaurs, ”explains Heck. It is also different from global warming today. “This global cooling was a gentle nudge. There was less stress. "

In view of the results of the study, one could come up with the idea that recurring large amounts of dust in the earth's atmosphere could stop - or even reverse - climate change. But Heck is careful: “You should be very careful with geoengineering. If something goes wrong, things could be worse than before. ”

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By Tanja Banner

* fr.de is part of the nationwide Ippen-Digital central editorial office.