Did Asteroids Cause 'Snowball Earth' Events?

Wednesday - April 10 2024, 09:00 UTC - 9 months ago

A new study by a Yale-led research team suggests that 'Snowball Earth' events, in which the entire planet was covered in ice, may have been triggered by large asteroid impacts. Using a sophisticated climate model, the team found that in certain climate scenarios, an asteroid strike could have pushed Earth into a 'Snowball' state in just 10 years. This could explain the dramatic climate shifts that occurred during the Neoproterozoic era. The study challenges existing theories about declining greenhouse gases and offers a new perspective on past climate events on Earth.

The 'Snowball Earth' debate has been raging in the scientific community for decades. This refers to a series of global deep freeze events that occurred during Earth's history where the entire planet was covered in ice for extended periods of time. While climate modelers have been able to predict how these events could have occurred, the exact cause has remained a mystery. But now, a new study led by researchers at Yale University, in collaboration with the University of Chicago and the University of Vienna, may have finally solved the puzzle. According to the team's findings, it's possible that these 'Snowball Earth' events were triggered by large asteroids that impacted the planet.

The study, published in Science Advances, expands on a theory that has been proposed before. Climate modelers have long known that if the Earth's temperature drops to a certain point, the high reflectivity of snow and ice can create a feedback loop that causes more cooling and more ice formation, eventually leading to a 'Snowball Earth' state. However, what was not known was what may have initiated these periods of global glaciation in the first place. This new research suggests that extraterrestrial impacts may have been the trigger.

Lead author, Minmin Fu, the Richard Foster Flint Postdoctoral Fellow in the Department of Earth and Planetary Sciences at Yale's Faculty of Arts and Sciences, explains: "What if an extraterrestrial impact caused this climate change transition very abruptly?" .

To test this theory, the team used a sophisticated climate model that simulates atmospheric and ocean circulation, as well as the formation of sea ice, under different scenarios. They applied their model to four distinct periods in Earth's history: preindustrial, Last Glacial Maximum, Cretaceous, and Neoproterozoic. The results of the study showed that in two of the warmer climate scenarios (Cretaceous and preindustrial), it was unlikely that an asteroid impact could have triggered 'Snowball Earth'. However, in the Last Glacial Maximum and Neoproterozoic scenarios, where Earth's temperature was already cold enough to be considered an ice age, an asteroid strike could have been the tipping point that pushed the planet into a 'Snowball' state.

Co-author, Alexey Fedorov, a professor of ocean and atmospheric sciences at Yale, explains how quickly this transition could occur: "What surprised me most in our results is that, given sufficiently cold initial climate conditions, a 'Snowball' state after an asteroid impact can develop over the global ocean in a matter of just one decade." This would have been too fast for plants and animals to adapt and migrate to more hospitable regions, potentially leading to mass extinctions.

The Yale-led team's findings may finally put an end to the debate over what caused these 'Snowball Earth' events. While previous theories have centered around a decline in greenhouse gases in the atmosphere, this study suggests that asteroid impacts may have played a role. If confirmed by further research, this could revolutionize our understanding of past climate events on Earth.