Roughly 650 million years ago vast sheets of glaciers stretched from the poles to the tropics, entombing Earth within a frozen skin that lingered for millions of years. And this had happened before: Our “pale blue dot” has transformed into a pearly-white “snowball Earth” at least three times in our planet’s history. But these deep freezes present a conundrum: They should have been deadly and yet life clearly survived. There is both geologic evidence our earliest microscopic ancestors did not freeze to death and genetic indications the lineages of a range of single-celled organisms extend beyond snowball Earth. The question is how.
A new study published to the preprint server arXiv and submitted to Earth and Planetary Science Letters might provide a resolution. Adiv Paradise, an astronomy graduate student at the University of Toronto (U.T.), and his colleagues modeled a variety of possible snowball worlds—varying the numbers of volcanoes