Gigantic collision in the asteroid belt – A boost for biodiversity on Earth?

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An international study by researchers at Lund University in Sweden found that a collision in the asteroid belt 470 million years ago resulted in drastic changes in life on Earth. The bursting of a major asteroid filled the entire inner solar system with enormous amounts of dust leading to a unique Ice Age and, subsequently, higher levels of biodiversity. This unexpected discovery could be relevant in the fight against global warming if we fail to reduce carbon dioxide emissions.

In recent decades, researchers have come to understand that the evolution of life on Earth also depends on astronomical events. An example of this is when the dinosaurs were instantly wiped out by the Cretaceous-Paleogenic impact of a 10 km asteroid.

For the first time, scientists can now present another example of how an alien event shaped life on Earth. 470 million years ago, a 150 km asteroid between Jupiter and ">March was crushed and dust spread through the solar system.

The dust blocking effect partially prevented sunlight from reaching Earth and an ice age began. The climate has gone from being more or less homogeneous to being divided into climatic zones – from arctic conditions at the poles, to tropical conditions at the equator.

The great diversity among invertebrates came as an adaptation to the new climate, triggered by the asteroid explosion.

“It’s analogous to standing in the middle of your living room and smashing a vacuum cleaner bag, but on a much larger scale,” says Birger Schmitz, professor of geology at Lund University and head of the study. .

An important method that led to the discovery was the measurement of extraterrestrial helium embedded in petrified sediments on the seabed at Kinnekulle in southern Sweden. On the way to Earth, the dust became enriched with helium when it was bombarded by the solar wind.

“This result was completely unexpected. Over the past 25 years, we have relied on very different assumptions about what happened. It wasn’t until we got the last helium measurements that everything fell into place, ”explains Birger Schmitz.

Global warming continues due to carbon dioxide emissions and the temperature increase is greatest at high latitudes. According to the Intergovernmental Panel on Climate Change, we are approaching a situation reminiscent of the conditions that prevailed before the asteroid collision 470 million years ago.

Over the past decade, researchers have discussed different man-made methods to cool the Earth in the event of a major climate disaster. Modelers have shown that it would be possible to place asteroids, much like satellites, in orbit around the Earth in such a way that they constantly release fine dust and thus partially block solar warming.

“Our results show for the first time that such dust has sometimes cooled the Earth considerably. Our studies can give a more detailed and empirical understanding of how it works, and this in turn can be used to assess whether model simulations are realistic, ”concludes Birger Schmitz.

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In addition to Lund University, the following universities and organizations participated in the study: California Institute of Technology, Vrije Universiteit Brussel, The Field Museum of Natural History, University of Chicago, Ohio State University, Université Libre de Bruxelles, Russian Academy of Sciences, Federal University Kazan, Royal Belgian Institute of Natural Sciences, Durham University, Chinese Academy of Sciences, Center for Excellence in Comparative Planetology China, ETH Zürich, Naturmuseum St. Gallen Switzerland , Woods Hole Oceanographic Institution.

Reference: “An Alien Trigger for the Middle Ordovician Ice Age: Dust from the Ruptured Parent Body of L-chondrite” by Birger Schmitz, Kenneth A. Farley, Steven Goderis, Philipp R. Heck, Stig M . Bergström, Samuele Boschi, Philippe Claeys, Vinciane Debaille, Andrei Dronov, Matthias van Ginneken, David AT Harper, Faisal Iqbal, Johan Friberg, Shiyong Liao, Ellinor Martin, Matthias MM Meier, Bernhard Peucker-Ehrenbrink, Bastien Soens, Rainer Wieler and Fredrik Terfelt, September 18, 2019, Scientists progress.
DOI: 10.1126 / sciadv.aax4184


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