GCM response to Late Precambrian (∼590 Ma) ice—covered continents

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.