- Between 640 and 720 million years ago, the Earth was covered in ice, earning it the modern nickname “Snowball Earth”.
- Recently, researchers found a rock formation that shows the transition from a warm, tropical planet to a harsh, icy one.
- Before the ice ages, only single-celled life existed on Earth.
Imagine a planet where the average temperature is cool -58° Fahrenheit every day. Not a place you want to visit, is it? Lucky for you, then, that you weren’t around a few hundred million years ago, because these brutal conditions were the unfortunate reality of Snowball Earth.
Between 640 and 720 million years ago, the Earth was covered pole-to-pole with slush and ice. Snowball Earth—a nickname that refers to how our planet must have looked from space at the time—was the reality of our planet during two ancient big freezes. And now, researchers may have found just the world’s most complete record of this ice age in part of a rock formation known as the Port Askaig Foundation.
In one new studypublished in Journal of the Geological Society of Londonresearchers took samples from the formation and tracked the decay of radioactive uranium to date the minerals. According to one RELEASE from University College London (UCL), this analysis – combined with additional existing geochemical evidence – helped the researchers conclude that the rock was likely formed during the Sturtian glaciation, which is the first of two major freezes during the Cryogenian period .
The most scientifically valuable piece was found in a group of Scottish islands called the Garvellachs. Unlike other rocks formed at a similar time, the “exposed outcrop” showed Earth’s transition from a warm tropical planet to an icy snowball.
“Most areas of the world are missing this remarkable transition because ancient glaciers eroded and eroded the rocks below,” Elias Rugen, one of the paper’s authors, said in the release, “but in Scotland the transition can be seen miraculously. “
The transition refers specifically to when the Earth began to form Snowball Earth, which likely occurred due to a “runaway” effect involving a phenomenon known as ice-albedo feedback. Simply put, ice forms and reflects light back into space, cooling the Earth and causing more ice to form. As more ice forms, even more light is reflected and the planet cools further. And in extreme cases, the Earth can become a complete snowball. In modern times, we are seeing the opposite effect – as the ice melts, the ocean begins to absorb more heat, temperatures rise and the ice sheets melt even faster.
The Sturtian glaciation (and the second glaciation that followed) was one of the most intense climatic conditions the Earth has ever seen. And yet, multicellular life flourished a little later. Researchers have various theories about why complex life forms suddenly appeared after the snowball — one of which, according to the release, is that the freezing conditions caused single-celled organisms to cooperate and form multicellular organisms.
But the frozen period didn’t last forever, and the rapid thaw that followed the Sturtian glaciation and preceded the Marinoan (second) glaciation helped shape life as we know it.
“Once the world warmed, all life would have to compete in an arms race to adapt,” Graham Shields, senior author of the paper and professor of Earth Sciences at UCL, said in the release. “Whatever survived were the ancestors of all animals.”
Emma Frederickson is a Pace University student by day, journalist by night. She enjoys covering everything from pop culture to science to food. Her work appears in several publications, including Biography.com AND Folk Mechanics. When not writing, Emma can be found cafe hopping in search of the world’s best oat milk cappuccino.