They discover the cause of the worst ice age the Earth has experienced
717 million years ago, the Earth began a glaciation that was much more intense and lasting than any known ice age. Almost the entire planet was covered in ice, in a state eloquently called “Snowball Earth.” What led to this situation? A recent study seems to have found an explanation.
The study was conducted by a team led by Adriana Dutkiewicz from the University of Sydney in Australia.
This colossal ice age lasted from 717 million years to 660 million years ago. Several reasons for such intense glaciation have been proposed, but the most puzzling aspect, as Dutkiewicz points out, is why it lasted 57 million years, much longer than other ice ages.
The team used a digital model of plate tectonics from the time, which shows the evolution of continents and ocean basins over time after the breakup of the ancient supercontinent Motherland. Dutkiewicz and his colleagues linked this to a computer model that calculates carbon dioxide (CO2) emissions from undersea volcanoes releasing gas along mid-ocean ridges (places where plates separate and new oceanic crust is born).
They soon realized that the onset of the superglaciation coincided precisely with the historic minimum of volcanic CO2 emissions. Moreover, CO2 flux remained relatively low throughout the Ice Age.
At this time, there were no multicellular animals or land plants. The concentration of greenhouse gases in the atmosphere was almost entirely dictated by the degassing of CO2 from volcanoes and the weathering processes of silicate rocks that consume CO2.
At that time, geology dominated the climate. All indications are that the superglaciation began due to a combination of two reasons: the rearrangement of tectonic plates reduced volcanic degassing to a minimum and, at the same time, the continental volcanic region in Canada began to erode, consuming atmospheric CO2.
As a result, atmospheric CO2 fell to pre-glaciation levels estimated to be below 200 ppm, less than half of current levels.
An artistic recreation of our planet during its Snowball Earth state. (Image: NASA)
The team’s work raises intriguing questions about the long-term future of Earth. A recent theory suggests that within the next 250 million years, Earth will transform into Pangea Ultima, a supercontinent so hot that mammals could go extinct.
However, the Earth is also currently on a trajectory of declining volcanic CO2 emissions as continental collisions intensify and plates slow down. So, perhaps some time after the creation of Pangea Ultima, the Earth will snowball again.
In any case, given the current rate of global warming caused by human activity, it is difficult to believe that the Earth will experience an ice age.
“Whatever the future holds, it is important to note that geological climate change of the type being studied here occurs extremely slowly,” Dutkiewicz warns. “According to NASA, human-caused global climate change is occurring 10 times faster than any known natural global climate change.”
The study is entitled “Duration of Sturtian Snowball Earth Glaciation Associated with Exceptionally Low Mid-Ocean Ridge Gas Emissions.” And it was published in the academic journal Geology. (Fountain: NCYT by Amazings)