Scientists believe that during the Neoproterozoic era 750 million years ago, a severe ice age occurred that almost completely froze Earth’s oceans. The factors that initiated this “Snowball Earth” have been the subject of much study.
Lewis et al. have instead focused on determining the factors that pulled Earth out of its snowball state.
Noting that accepted values for both snow and ice albedo (ratio of incident and reflected solar radiation) cover a wide range, the authors sought to quantify the relative sensitivity of various surface albedos on the same climate model, as that model is pulled out of a snowball state.
They found the range of ice, snow, and land albedos and the resulting minimum carbon dioxide greenhouse forcing required for deglaciation of the Neoproterozoic snowball Earth. They also found that greenhouse forcing can vary by nearly an order of magnitude within the accepted albedo ranges, suggesting that the physics of deglaciation in terms of radiation budgets, snow and ice dynamics, and atmospheric processes needs to be better modeled.
Title: Deglaciating the snowball Earth: Sensitivity to surface albedo
Authors: J. P. Lewis, A. J. Weaver, and M. Eby: School of Earth and Ocean Sciences, University of Victoria, British Columbia, Canada.
Source: Geophysical Research Letters (GRL) paper 10.1029/2006GL027774, 2006