Life, geology and snowball Earth

Abstract

According to the 'snowball Earth' hypothesis, a series of global glaciations occurred 750–580 million years ago, each lasting for millions of years and ending in a scorching heat caused by an extreme enrichment of atmospheric greenhouse gases. Hyde et al.1 have used climate models to simulate this global glaciation, finding in one case an alternative climate scenario in which a partially frozen Earth has ice-free oceans equatorward of 25° latitude. We do not believe that this 'slushball' Earth is consistent with the most striking geological and palaeomagnetic observations explained by the snowball Earth hypothesis.