Were the world's oceans in cryogenium - around 700 million years ago - completely covered with ice or an ice-free water belt stretched around the equator, in which sponges and other life forms could survive? A research team from the Karlsruhe Institute of Technology (KIT) and the University of Vienna has now been able to show in global climate models that a climate condition with a water belt is rather unlikely and therefore not a reliable explanation for the persistence of life in the cryogenium. The reason for this is the uncertain influence of clouds on the climate at that time. The team presents the results of the study in the journal Nature geoscience.
From space, Earth might have looked like a big snowball during the global ice ages in the Cryogenium. Geoscience therefore describes this assumption of a closed sea ice sheet established in research as a snowball earth theory. It is still particularly unclear how sponges - of which fossil finds testify - could have survived in the very cold snowball earth climate. Therefore, some researchers have proposed an ice-free water belt around the equator as an alternative theory.





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