Researchers at Harvard have proposed a new explanation for the Sturtian glaciation, a period when Earth was nearly frozen for 56 million years. The study suggests the planet did not stay frozen in one long stretch but instead cycled between snowball and hothouse states. This cycling was driven by the weathering of basalt in northern Canada, which pulled carbon dioxide from the atmosphere to trigger cooling. As volcanic activity rebuilt CO2 levels, the planet warmed, exposing more basalt and restarting the cooling cycle.
