Recent coupled energy balance/ice sheet modeling studies indicate that ice-covered continents can be simulated for the Late Precambrian with 6% solar constant reduction. We examine the ocean mixed layer response to such an ice sheet with the GENESIS 2 general circulation model and CO2 levels varying from 0.5--2.5 times present. The ocean ices over completely at 0.5--1.0X present levels, with the final phase of sea ice growth occurring within a single model year. A qualitatively different 2.5X CO2 solution is close to equilibrium and yields open water between ~25 ¿N and ~25 ¿S paleolatitude. The prevailing wind patterns suggest that an equatorial Pacific-type circulation may have developed in part of the Neoproterozoic ocean. ¿ 2001 American Geophysical Union