Testing paleogeographic controls on a Neoproterozoic snowball Earth

The distribution of continents during the Neoproterozoic has been hypothesized to play an important role in the initiation of an ice-covered Earth. In this study, the influence of paleogeography on the Neoproterozoic climate is evaluated using a fully coupled ocean-atmosphere general circulation model (FOAM). Three simulations were completed with different continental distributions. Each simulation included a reduced solar luminosity (93% of present-day) and low atmospheric CO₂ (140 ppmv). Model results indicate that a low-latitude concentration of continents leads to lower tropical temperatures, through reduced receipt of shortwave radiation and a smaller tropical greenhouse effect, but does not significantly affect high-latitude temperatures or sea-ice extent. In contrast, the presence of snow-covered, mid- and high-latitude continents increases the sensible heat transport over the ocean, giving rise to sea-surface cooling, deep-water formation, and an advanced sea-ice margin. Nonetheless, an ice-covered Earth is not simulated in these experiments.