It is believed that the Earth became a giant snowball about 700 million years ago following unusual episodes of global cooling, but scientists have long been stumped trying to figure out exactly what had triggered this dramatic cooldown.
Why Did The Earth Turn Into A Snowball Hundreds Of Millions Ago?
There have been many theories attempting to explain this global catastrophe, which occurred during the Neoproterozoic era. Two geologists from the University of Texas at Dallas and Austin have a new one: Snowball Earth happened because of plate tectonics.
Their study was first published online in December 2017 and now appears in the print edition of the Terra Nova journal.
Plate tectonics is a theory popularized in the late '60s, which assumes that the planet's crust and upper mantle are made up of fragmented moving pieces. These plates move very slowly — about as fast as nail and hair growth — and their movements cause earthquakes, volcanoes, and mountain ranges.
Earth, according to geosciences professor Robert Stern, is the only planet known to have plate tectonics, where the lithosphere is broken up into pieces that move independently. Stern, along with research scientist Nathaniel Miller, authored a study that provides new insights into what caused the Snowball Earth phenomenon.
From Single Lid To Plate Tectonics
Geoscientists generally disagree on when Earth transitioned from single lid — a planet which has an outer solid shell that's not fragmented — into plate tectonics. Stern, however, highlights geological and theoretical evidence that suggest plate tectonics occurred between 600 to 800 million years ago.
In their study, Stern and Miller posit that the onset of plate tectonics likely triggered dramatic changes on the Earth's surface that caused it to turn into a giant snowball. As part of their research, they studied all the mechanism other scientists have tied to the global phenomenon.
"We went through the literature and examined all the mechanisms that have been put forward for Snowball Earth," said Stern. "The start of plate tectonics could be responsible for each of these explanations."
When Earth Transitioned Into Plate Tectonics, This Is What Happened
One notable evidence that supports Stern and Miller's theory is the fact that strong climate and oceanographic effects were observed during the Neoproterozoic era, which indicates that it was indeed the time when Earth transitioned from single lid to plate tectonics.
"The transition should have disturbed the oceans and atmosphere by redistributing continents, increasing explosive arc volcanism, stimulating mantle plumes and disrupting climate equilibrium established by the previous balance of silicate‐weathering greenhouse gas feedbacks," the study's abstract reads.
Any geoscientists out there who'd like to dispute this theory? Feel free to sound off in the comments section below!