The climate of our planet changed wildly 700 million years ago, and the Earth experienced several unusual episodes of global cooling. This frosty period is commonly referred to as "Snowball Earth" and scientists now think they know what caused it. Plate Tectonics.
The Earth's crust has experienced tectonic movements since its formation but between 800 and 600 million years ago, the supercontinent of Rodinia began to crack. The date range roughly coincides with Snowball Earth, but for researchers at the University of Texas (UT) in Dallas and in Austin, it’s not a coincidence. As reported in the journal Terra Nova, the team looked at the 22 likely causes of the global cooling and found that all of them could be consequences of plate tectonics.
"We went through the literature and examined all the mechanisms that have been put forward for Snowball Earth. The start of plate tectonics could be responsible for each of these explanations," lead author Robert Stern, professor of geosciences at UT Dallas, said in a statement.
"Earth is the only body in our Solar System known to currently have plate tectonics, where the lithosphere is fragmented like puzzle pieces that move independently. It is much more common for planets to have an outer solid shell that is not fragmented, which is known as 'single lid tectonics'."
The geological epoch of Snowball Earth, known as the Neoproterozoic, saw dramatic changes to the planet. The formation of plate tectonics changed oceans, disturbed the atmosphere, and led to the formation of mountains and shallower seas. It also resulted in the formation of volcanic chains as well as changes in Earth's mantle.
"The fact that strong climate and oceanographic effects are observed in the Neoproterozoic time is a powerful supporting argument that this is indeed the time of the transition from single lid to plate tectonics," Stern added. "It's an argument that, to our knowledge, hasn't yet been considered.
"In the present day, climate is in the news because we're changing it by putting more carbon dioxide into the atmosphere. But imagine a time when Earth didn't have plate tectonics, and it then evolved to have plate tectonics – that would have been a major shift in the Earth's operating system, and it would have had a huge effect on climate, too."
There are currently seven major plates on Earth and several smaller ones. They are moving at a speed similar to the one our fingernails grow at and are responsible for shaping the appearance of our planet.
