Discovering Earth’s Oldest Asteroid Crater: How Its Identification Could Transform Our Understanding of Climate Change

In the Midwest of Western Australia, scientists have discovered the oldest known asteroid impact site on Earth: the Yarrabubba crater. This incredible site dates back 2.229 billion years, making it older than any previously identified impact crater.

Located near Meekatharra, about 600 kilometers northeast of Perth, the Yarrabubba crater spans 70 kilometers wide. Over billions of years, erosion has worn down its distinct features, making it more challenging to identify compared to younger, well-preserved craters.

The Yarrabubba crater was first noticed in the early 2000s, but researchers couldn’t determine its age until a team from Curtin University and Imperial College London conducted a detailed analysis. They examined minerals like zircon and monazite, which contain uranium. As uranium decays into lead over time, measuring this decay allowed the scientists to establish the crater’s age accurately.

The findings, published in Nature Communications, confirmed the impact occurred 2.229 billion years ago. Lead researcher Chris Kirkland noted that this discovery not only identifies Yarrabubba as the oldest impact structure but also raises questions about how these early impacts might have shaped Earth’s climate.

Interestingly, the age of Yarrabubba aligns with the end of the Huronian glaciation, a time when Earth was largely covered in ice. Some researchers speculate that this impact might have played a role in warming the planet.

A team led by Thomas Davison from Imperial College conducted simulations of an asteroid hitting an ice-covered Earth. Their models suggested that such an impact could release over 200 billion tons of water vapor into the atmosphere. Given that water vapor is a potent greenhouse gas, this sudden influx might have triggered a warming trend, pulling Earth out of its ice age.

Nicholas Timms, a geologist at Curtin University, stated, “We see a remarkable coincidence between the age of Yarrabubba and the termination of a global glaciation. If this impact released enough water vapor, it might have tipped the climate toward warming.”

Finding Yarrabubba was no simple task. Unlike the more recognizable Chicxulub crater in Mexico, which marks a recent impact, Yarrabubba’s features have been erased by erosion and tectonic activity. Researchers identified it through magnetic anomalies that hinted at a hidden impact structure beneath the surface. They also found evidence of shock metamorphism in deep rock samples, confirming its extraterrestrial origins.

The discovery of Yarrabubba changes our understanding of Earth’s history and the role asteroid impacts might have played in climate change. It prompts scientists to ask how such impacts could influence long-term climate cycles. Could future asteroid collisions also lead to significant changes in our climate?

As Chris Kirkland remarked, “This discovery reminds us that asteroid impacts are not just catastrophic events. They are also powerful forces of planetary change.” Yarrabubba, though worn away, remains an essential part of our planet’s story.