The Snowball Earth hypothesis

The Snowball Earth hypothesis suggests that during certain periods in Earth's history, the planet was entirely or nearly completely covered in ice, including the oceans. This phenomenon likely occurred around 700 million years ago. Scientists believe it was triggered by a combination of reduced greenhouse gases and changes in the Earth's orbit and sunlight. The ice cover would have created a feedback loop, reflecting sunlight and cooling the planet further. Eventually, volcanic activity released enough carbon dioxide to warm the Earth, melting the ice and allowing life to flourish again, paving the way for the evolution of more complex organisms.