Snowball Earth theory: Salt deposits may have intensified ancient glaciations

Research suggests that salt deposits may have played a critical role in the ‘Snowball Earth’ episodes occurring between 750 and 580 million years ago. Scientists from the University of Tromsø investigated how salt crystals could accumulate on extremely cold sea ice through a process involving sublimation. These salt crusts significantly increase the surface reflectivity, or albedo, of the ice. Laboratory experiments indicate that salt crusts can reflect approximately 93% of incident sunlight, compared to 83% for fresh snow and 67% for melting sea ice, creating a feedback loop that intensifies planetary cooling.

While Earth undergoes natural glacial cycles driven by Milankovitch cycles—changes in the planet's orbit and axial tilt—human-induced carbon dioxide emissions may alter the timing and evolution of future glaciations. Although the planet is currently in a warm interglacial period of the Quaternary, the natural mechanisms for ice sheet expansion remain active, though potentially delayed by atmospheric changes.