Salt crystallization may have accelerated Snowball Earth freezing

Researchers have identified a mechanism that may have intensified the ‘Snowball Earth’ period approximately 700 million years ago. A study led by Aksel Samuelsberg at The Arctic University of Norway suggests that salt crystallization played a critical role in accelerating global freezing.

As seawater freezes, salt is expelled from the ice crystals and accumulates on the surface. This creates a ‘salt albedo feedback’ loop where the salt crystals act like reflective powder, reaching an albedo of up to 93%. This is significantly higher than pure snow (83%) or bare sea ice (67%), meaning more sunlight is reflected back into space, further lowering temperatures and driving more ice formation.

This self-reinforcing cycle explains how ice could have expanded toward the equator, locking the planet in a deep freeze for millions of years. The eventual thawing of the planet is attributed to volcanic activity, which released massive amounts of CO2 into the atmosphere, eventually creating a greenhouse effect strong enough to overcome the high reflectivity of the ice.