Recent research suggests that asteroid impacts may have triggered large-scale ice ages in Earth’s ancient history. A Yale University-led research team has chosen its side in the “Snowball Earth” debate over the possible cause of the planet’s deep freeze in the distant past.

These “snowball” Earth periods, in which the planet’s surface is covered in ice for thousands or even millions of years, may have been triggered by sudden impacts of large asteroids on Earth, according to a new study.

The findings are detailed in the journal Science Developmentscould answer a question that has baffled scientists for decades about some of the most dramatic climate changes in Earth history. In addition to Yale University, researchers from the University of Chicago and the University of Vienna also participated in the research.

Since the 1960s, climate modelers have known that if the Earth gets cold enough, the high reflectivity of snow and ice can create an “emergent” feedback loop that will create more sea ice and colder temperatures until the planet is covered in ice. Such conditions occurred at least twice during Earth’s Neoproterozoic period, between 720 and 635 million years ago.

However, attempts to explain what caused these periods of global glaciation, referred to as “Snow-Earth” events, have been inconclusive. Most theories focus on the idea that greenhouse gases in the atmosphere somehow decrease to the point where a “snowball” begins.

A New Look at Global Glaciation

“We decided to investigate an alternative possibility,” said lead author Mingming Fu, the Richard Foster Flint Postdoctoral Fellow in the Department of Earth and Planetary Sciences at Yale University School of Arts and Sciences. “What if an extraterrestrial impact caused this climate change transition to be so sudden?”

For the study, the researchers used a complex climate model that reflects the circulation of the atmosphere and ocean, as well as the formation of sea ice under different conditions. This is the same type of climate model used to predict future climate scenarios.

In this case, the researchers applied their model to the effects of a hypothetical asteroid impact at four different periods in the past: pre-industrial (150 years ago), last glacial maximum (21,000 years ago), and Cretaceous (145 to 66 million years ago). and Neoproterozoic (1 billion to 542 million years ago).

For the two warmer climate scenarios (Cretaceous and pre-industrial), the researchers found that an asteroid impact was less likely to trigger global glaciation. However, for the Last Glacial Maximum and Neoproterozoic scenarios, when Earth’s temperature is low enough to be considered an ice age, an asteroid impact could send Earth into a “snowball” state.

“What surprised me most about our results was that, given sufficiently cold initial climate conditions, a ‘snowball’ situation could occur over the global ocean within just a decade after the asteroid impact,” said ocean professor Oleksiy Fedorov. science and atmosphere at Yale University School of Arts and Sciences. “Then the thickness of sea ice at the equator will reach about 10 meters. This should be compared with the thickness of typical sea ice in the modern Arctic of one to three metres.”

As for the possibility of an asteroid-induced Snowball Earth period in the coming decades, the researchers said that’s unlikely due in part to human-caused warming warming the planet, though other impacts would be just as devastating.