of Sturtian “Snowball Earth” Ice Age (717 million to 661 million years ago) is considered the most extreme icehouse period in Earth’s history. In a new study, geologists from the University of Sydney and the University of Adelaide used plate tectonics modeling to identify the most likely cause of the Staats Ice Age.
Artist’s impression of “Snowball Earth”. Image credit: Oleg Kuznetsov, http://3depix.com / CC BY-SA 4.0.
“Imagine if the Earth almost completely froze over, which is exactly what happened about 700 million years ago,” said lead author Dr. Adriana Dutkiewicz, a researcher at the University of Sydney. .
“The Earth was covered in ice from the poles to the equator, and temperatures plummeted. But what caused this to happen is an open question.”
“We think we have now solved the mystery. Historically, volcanic carbon dioxide emissions have been low, driven by the weathering of large volcanic rock mountains in what is now Canada. It’s a process that absorbs carbon dioxide.”
Named after Charles Sturt, a 19th-century European colonial explorer of central Australia, the Sturtsian Ice Age spanned 717 million to 660 million years, long before dinosaurs and complex plants existed on land. It continued until ten thousand years ago.
“There are many possible causes for the trigger and end of this extreme ice age, but the most mysterious one is why it lasted 57 million years. It’s hard for humans to imagine,” Dr. Dutkiewicz said.
Dr. Dutkiewicz and his colleagues used a plate tectonics model that simultaneously shows the evolution of continents and ocean basins after the breakup of the ancient supercontinent Rodina.
They connected it to a computer model that calculates the outgassing of carbon dioxide from submarine volcanoes along mid-ocean ridges, where plates diverge and new oceanic crust is born.
They soon realized that the beginning of the Starch Ice Age correlated precisely with the lowest ever levels of volcanic carbon dioxide emissions.
Additionally, carbon dioxide flux remained relatively low throughout the ice age.
“At that time, there were no multicellular animals or land plants on Earth,” Dr. Dutkiewicz said.
“Greenhouse gas concentrations in the atmosphere were determined almost entirely by carbon dioxide emitted by volcanoes and by the weathering processes of silicate rocks that consume carbon dioxide.”
“At that time, geology ruled the climate,” said co-author Professor Dietmar Müller, a researcher at the University of Sydney.
“We think the Staats Ice Age began with a double whammy: plate tectonics realigned to minimize volcanic degassing, while at the same time Canada’s continental volcanic belt began to erode, removing carbon dioxide from the atmosphere. Consumed.”
“As a result, atmospheric carbon dioxide has fallen to levels that could begin an ice age. This is estimated to be less than 200 parts per million, less than half of today’s levels.”
The team’s current research raises interesting questions about the long-term future of the planet.
Recent theories suggest that over the next 250 million years, Earth will evolve toward Pangea Ultima, a supercontinent hot enough to wipe out mammals.
However, the Earth is currently on a trajectory where volcanic carbon dioxide emissions decrease as continental collisions increase and plate velocities decrease.
So perhaps Pangea Ultima will snowball again.
“Whatever the future holds, it is important to remember that geological climate changes of the type studied here occur very slowly,” Dr. Dutkiewicz said.
“According to NASA, human-induced climate change is occurring 10 times faster than ever before.”
of study appear in the diary geology.
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Adriana Dutkiewicz other. The period of the Sturtian “Snowball Earth” ice age is associated with unusually low gas emissions at mid-ocean ridges. geology, published online on February 7, 2024. doi: 10.1130/G51669.1
Source: www.sci.news
