>[!abstract] >The White Earth climate hypothesis describes a theoretical planetary state in which runaway ice–albedo feedback leads to near-total glaciation, with Earth’s surface becoming almost entirely frozen. As ice sheets expand, they increase Earth’s reflectivity (albedo), reducing heat absorption and further accelerating cooling, creating a self-reinforcing cycle. A “Snowball Earth” episode is thought to have occurred during the Proterozoic eon, profoundly shaping biological and geological evolution. The concept illustrates how nonlinear feedbacks can drive the climate into extreme stable states, highlighting the fragility of Earth’s energy balance and the potential for abrupt global transitions. >[!quote] >Climatologists who use global computer models to simulate the long-term behavior of the earth's atmosphere and oceans have known for several years that their models allow at least one dramatically different equilibrium. During the entire geological past, this alternative climate has never existed, but it could be an equally valid solution to the system of equations governing the earth. It is what some climatologists call the White Earth climate: an earth whose continents are covered by snow and whose oceans are covered by ice. A glaciated earth would reflect seventy percent of the incoming solar radiation and so would stay extremely cold. The lowest layer of the atmosphere, the troposphere, would be much thinner. The storms that would blow across the frozen surface would be much smaller than the storms we know. In general, the climate would be less hospitable to life as we know it. Computer models have such a strong tendency to fall into the White Earth equilibrium that climatologists find themselves wondering why it has never come about. It may simply be a matter of chance ([[Gleick, 1987]], p. 170). >[!related] >- **North** (upstream): [[Intransitive systems]], [[Paleoclimatology]] >- **West** (similar): — >- **East** (different): [[Hothouse Earth]] (runaway warming scenarios with reduced ice cover and amplified greenhouse effects) >- **South** (downstream): [[Ice–albedo feedback]]