Editing Snowball Earth (section)

===During the frozen period===
[[Image:AntarcticaDomeCSnow.jpg|thumb|250px|Global ice sheets may have created the bottleneck required for the evolution of multicellular life.<ref name=Kirschvink1992 />]]
Global temperature fell so low that the equator was as cold as modern-day Antarctica.<ref name=Hyde2000>{{cite journal |last1=Hyde |first1=William T. |last2=Crowley |first2=Thomas J. |last3=Baum |first3=Steven K. |last4=Peltier |first4=W. Richard |title=Neoproterozoic 'snowball Earth' simulations with a coupled climate/ice-sheet model |journal=[[Nature (journal)|Nature]] |date=May 2000 |volume=405 |issue=6785 |pages=425–429 |doi=10.1038/35013005 |pmid=10839531 |bibcode=2000Natur.405..425H |s2cid=1672712 }}</ref> This low temperature was maintained by the high albedo of the ice sheets, which reflected most incoming solar energy into space. A lack of heat-retaining clouds, caused by water vapor freezing out of the atmosphere, amplified this effect. Degassing of carbon dioxide has been speculated to have been unusually low during the Cryogenian, enabling the persistence of global glaciation.<ref>{{cite journal |last1=Mills |first1=Benjamin J. W. |last2=Scotese |first2=Christopher R. |last3=Walding |first3=Nicholas G. |last4=Shields |first4=Graham A. |last5=Lenton |first5=Timothy M. |date=24 October 2017 |title=Elevated CO2 degassing rates prevented the return of Snowball Earth during the Phanerozoic |journal=[[Nature Communications]] |volume=8 |issue=1 |page=1110 |doi=10.1038/s41467-017-01456-w |pmid=29062095 |pmc=5736558 }}</ref>