Sea glacier flow and dust transport on Snowball Earth

Abstract

[1] Accumulation of dust on the surface of ice in the tropics has been proposed as a possible mechanism for the termination of Neoproterozoic Snowball Earth episodes. This Mudball hypothesis relies on the assumption that sea glacier flow transports dust to the tropical ablation zone, leading to the accumulation of a dust moraine there and consequent lowering of tropical albedo. Here, we use a 1-D sea-glacier flow model to simulate the ice thickness and flow on a globally glaciated Earth, and study the dust transport associated with the ice flow. Dust is entirely confined to a meteoric ice layer which does not exchange water with the ocean. Dust falling onto the surface of this layer is carried downward with the ice flow in extratropical regions, carried equatorward by the global ice flow, and re-emerges on the top of the ice in the tropical ablation zone. The ice flow acts as a dust conveyor belt which converges dust to tropics, resulting in an amplification of effective tropical dust flux by a factor of 2 to 20 over the global average. This lends support to the Mudball hypothesis.