Neoproterozoic 'snowball Earth': Dynamic sea ice over a quiescent ocean

摘要

Low-latitude sea level glacial deposits suggest the existence of "snowball Earth" conditions in the Neoproterozoic. Previous modeling studies have offered conflicting support for the snowball hypothesis. We use a climate model of intermediate complexity, including an ocean GCM and a sophisticated thermodynamic/dynamic sea ice component, to conduct a suite of experiments with different orbital/paleogeographical configurations, wind-forcing, and atmospheric CO_2 levels. We show that depending on the orbital configuration and paleogeography, snowball conditions prevail even with atmospheric CO_2 levels up to 1800 ppmv. Overall, our modeling paradigm is consistent with the original snowball hypothesis in which an ice covered ocean surrounds a largely snow and ice-free barren land, with some coastal regions permitting the growth of thick glaciers.