Francis A. Macdonald and his team have reached this conclusion after analyzingthe composition and magnetism of tropical rocksfound in the extreme northeast ofCanadathat showed glacial deposits, and that 716.5 million years ago were at sea level in the Tropics, about10 degrees latitude. ? Due to the high albedo of the ice, the climate model has predicted that if sea ice ever reached 30 degrees latitude from the equator, the entire ocean would quickly freeze ,? says the lead author, thus demonstrating that the study allows to deduce “quite safely” thatthere was ice at all latitudes during the Sturtian glaciation.
The most surprising thing is that? The fossil record suggests that allthe main eukaryotic groups, with the possible exception of animals,had arisen beforeof the Sturtian glaciation ?, says Macdonald. And if there was a “snowball” Earth, how is it possible that eukaryotes survived? Was it the Sturtian glaciation that spurred the evolution and origin of animals? ? Even on a “snowballing” Earth there would be temperature gradients, and it is very likely that the ice was dynamic: flowing, weakening, and forming local areas of open water, thus providing havens for life ,? Macdonald emphasizes . “From the perspective of evolution, facing extreme situations is not always negative for life on Earth.“, suggest the researchers, who have published their study in the journalScience.
