EARTH WAS ONCE COMPLETELY FROZEN: THE SNOWBALL ERA EXPLAINED Around 700 million years ago, our planet experienced a dramatic climate shift known as the Snowball Earth. During this time, ice sheets stretched from the poles to near the equator, covering almost the entire globe. Scientists believe this extreme glaciation was triggered by changes in atmospheric carbon dioxide, continental positions, and ocean circulation. Life managed to survive in small ice-free refuges, such as around hydrothermal