Discoveries

April 17, 2023

The Slushball

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The Cryogenian Period, often referred to as “Snowball Earth,” was a time in Earth’s history when the planet experienced extreme global glaciation, with ice sheets covering much of the planet’s surface.

Occurring between 720 million and 635 million years ago, this era was extremely challenging for life on Earth, as the severe cold and extensive ice cover would have made it difficult for complex organisms to survive.

Previous research had suggested that habitable areas during the Cryogenian Period were limited to tropical oceans, where some pockets of open water allowed early living things to thrive.

However, a research team found evidence that our planet was more of a “slushball Earth” because habitable marine environments were more widespread than previously thought, Reuters reported.

For their study, researchers identified fossils of seaweed in black shale in China’s Hubei Province dating from the Marinoan Ice Age – the second and most severe glaciation event of the Cryogenian Period.

Their presence during this harsh period indicates that there were areas in mid-latitude oceans that were ice-free and habitable during the waning stage of the Marinoan, which lasted from about 651 million to 635 million years ago.

This suggests that the world’s oceans were not completely frozen over, and there were refuges where early complex life forms, such as multicellular seaweed, could have survived.

The findings have important implications for our understanding of the resilience of life on Earth. It also underscores the ability of life to adapt and persist even in the face of severe environmental challenges.

This story originally appeared in the April 17, 2023 newsletter, Fair Weather Friend.