A consortium of researchers from the University of Chicago, Yale University, and the University of Vienna examined a long standing mystery from Earth’s deep past: why the planet might have frozen over completely during the Neoproterozoic era, more than 700 million years ago. They explored the hypothesis that meteorite encounters could have triggered a runaway cooling trend that pushed the climate into a global ice state.
Geological records indicate that roughly 717 million years ago the Earth appeared as a frozen sphere, with ice sheets extending from the poles toward the equator. This icehouse persisted for tens of millions of years, shaping a world where ice could cover nearly every latitude. The researchers investigated how a sudden external impact could disrupt atmospheric and oceanic circulation in ways that promote rapid sea ice growth under a range of environmental settings.
Using advanced computer models that simulate atmospheric chemistry, wind patterns, ocean currents, and the formation of sea ice, the team tested scenarios in which a large asteroid could initiate widespread cooling. The simulations demonstrated that an asteroid impact could drive the global climate into a snowball state within about a decade. In such a scenario, equatorial ice might reach thicknesses of around ten meters, substantially exceeding present Arctic ice thickness. The rapid transition would be possible because the Earth at that time already hosted cooler baseline conditions, which would amplify the cooling feedbacks after a large impact.
Earlier explanations for the global icing of the Earth focused on a natural downturn in volcanic carbon dioxide emissions, which would reduce the greenhouse effect and allow ice to advance. The new modeling work provides an alternative mechanism that could operate in parallel with volcanic trends, underscoring how external impacts might act as a catalyst for dramatic climate shifts in deep time.
Overall, the findings offer a plausible pathway by which a single extraterrestrial event could tip the climate into an enduring ice state, aligning with paleoclimate evidence that points to prolonged global glaciation during the late Neoproterozoic. The work demonstrates the importance of considering both internal geochemical cycles and external perturbations when reconstructing Earth’s climatic history.