Toward the snowball earth deglaciation...
Résumé
The current state of knowledge suggests that the Neoproterozoic snowball Earth is far from deglaciation even at 0.2 bars of CO2. Since understanding the termination of the fully ice-covered state is essential to sustain, or not, the snowball Earth theory, we used an Atmospheric General Climate Model (AGCM) to explore some key factors which could induce deglaciation. After testing the models' sensitivity to their parameterizations of clouds, CO2 and snow, we investigated the warming effect caused by a dusty surface, associated with ash release during a mega-volcanic eruption. We found that the snow aging process, its dirtiness and the ash deposition on the snow-free ice are key factors for deglaciation. Our modelling study suggests that, under a CO2 enriched atmosphere, a dusty snowball Earth could reach the deglaciation threshold.