Snowfall-albedo feedbacks could have led to deglaciation of snowball Earth starting from mid-latitudes

• Published in: Communications earth & environment Vol. 2; no. 1
• Main Authors: de Vrese, Philipp, Stacke, Tobias, Caves Rugenstein, Jeremy, Goodman, Jason, Brovkin, Victor
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group 01-12-2021
• Subjects: Albedo; Atmospheric models; Carbon dioxide; Climate models; Deglaciation; Deposition; Dust; Earth; Fluxes; Hydrologic cycle; Hydrology; Ice cover; Precipitation; Simulation; Snow; Snow accumulation; Tropical environments
• ISSN: 2662-4435; 2662-4435
• DOI: 10.1038/s43247-021-00160-4

Abstract
Simple and complex climate models suggest a hard snowball – a completely ice-covered planet – is one of the steady-states of Earth’s climate. However, a seemingly insurmountable challenge to the hard-snowball hypothesis lies in the difficulty in explaining how the planet could have exited the glaciated state within a realistic range of atmospheric carbon dioxide concentrations. Here, we use simulations with the Earth system model MPI-ESM to demonstrate that terminal deglaciation could have been triggered by high dust deposition fluxes. In these simulations, deglaciation is not initiated in the tropics, where a strong hydrological cycle constantly regenerates fresh snow at the surface, which limits the dust accumulation and snow aging, resulting in a high surface albedo. Instead, comparatively low precipitation rates in the mid-latitudes in combination with high maximum temperatures facilitate lower albedos and snow dynamics that – for extreme dust fluxes – trigger deglaciation even at present-day carbon dioxide levels.