Through thick and thin: Marine and meteoric ice in a “Snowball Earth” climate

Marine ice cover in the frigid Neoproterozoic climate system tends to isolate the ocean: the thickness of this ice, and thus the degree of isolation, is an important unknown in geochemical and biological arguments regarding the fully‐glaciated “Snowball Earth” hypothesis. The Pollard and Kasting (2005) coupled atmosphere/ice model has been modified to track ice of marine and atmospheric origin separately, and model their different optical properties. In contrast to Pollard and Kasting's results, a tropical region of thin ice is not stable in this model: ice is hundreds of meters thick everywhere. The overall pattern of the hydrological cycle in a Snowball climate is also discussed.