Amplified Cooling Of Snowball Earth From A Salt-albedo Feedback

[Climate of the Past] It is believed that the atmospheric circulation on Snowball Earth produced a net ablation zone exposing bare sea ice.

Under sufficiently low temperatures, salt begins to precipitate out of sea ice, forming a lag deposit of crystals with high albedo as the ice sublimates. This could have resulted in a salt-albedo feedback that has not previously been included in modeling studies of Snowball Earth.

We implement a salt-albedo feedback in a simple climate model and show that, once initiated, this mechanism could have intensified global cooling in the initial phase of Snowball Earth. Our results suggest that salt precipitation may have played a role in shaping the early climate of Snowball Earth.

Bifurcation diagram for the EBM with a salt-albedo feedback (Eq. 1 with the albedo function in Eq. 2). Radiative forcing on the x axis is defined as , where A0 is the reference value given in Table 1. Black solid lines indicate stable equilibrium states and dashed lines indicate unstable states. Stable climate states are labeled. The branch terminating at b6 extends beyond the plotted frame. Likewise, the branch originating in b1 extends beyond the frame. Gray solid arrows show transitions in the Snowball Earth hysteresis. The dashed arrow indicates the unfeasible transition from a warm climate to a Snowball Earth without salt deposits. Model parameters are given in Table 1. The gray line between point b4 and b5 represents a truncation where Snowball Earth states with multiple salt deposits are omitted, the situation here is analogous to the complicated ice distributions reported in Samuelsberg and Jakobsen (2025b). These solutions are unstable. — Climate of the Past

Amplified cooling of Snowball Earth from a salt-albedo feedback, Climate of the Past (open access)

Astrobiology,