The world's oldest asteroid struck Earth 2.2 billion years ago triggering one of the first global warming episodes in history

• The Yarrabubba Crater in Australia has been identified as the oldest asteroid impact site in the world dating back 2.229 billion years.
• The age of the crater is nearly half that of Earth.
• The time of the impact coincides with when Earth came out of the deep freeze.
• Scientists believe the impact released nearly half a trillion tons of water vapour into the air triggering one of Earth’s first episodes of global warming.

The world’s oldest asteroid struck 2.2 billion years ago and it might have been the reason why the Snowball Earth finally melted.

Till now, the oldest asteroid impact on Earth was the Vredefort Dome in South Africa. However, researchers at Curtin University have found that new asteroid impact crater in Australia dates back even further to 2.229 billion years. That’s half as old as the Earth itself.

And, it was around the same time that scientists believe Snowball Earth — or the global deep freeze — ended. The discovery, published in Nature Communications, states that the Yarrabubba asteroid might have been the reason why and could be the key to unlocking Earth’s frozen past.

Half a trillion tons of water vapour that ended the glaciers
When the asteroid struck Earth’s ice-covered landscape billions of years ago, it vapourised ice into nearly half a trillion tons of water vapour. Since water vapour is an important gas, it may have been enough to tip the scales to trigger global warming.

According to Timmons Erickson, lead author of the study, the age of Yarrabubba impact crater coincides with when a series of ancient glaciers disappeared.

"Now we know the Yarrabubba crater was made right at the end of what’s commonly referred to as the early Snowball Earth -- a time when the atmosphere and oceans were evolving and becoming more oxygenated and when rocks deposited on many continents recorded glacial conditions," said Erickson.

As it crashed into the surface, it produced a 70-kilometre crater. However, its actual impact reached far beyond just the Earth’s surface, to affecting its climate as well.

"After the impact, glacial deposits are absent in the rock record for 400 million years. This twist of fate suggests that the large meteorite impact may have influenced global climate," said Nicholas Timms, co-author of the paper.

The study supports its correlation between the asteroid impact and the glaciers melting using numerical modelling. According to it, the connection between the effects of large impacts on ice and global climate is difficult to deny.

The Yarrabubba crater may only be one of many craters that are yet to be discovered. Erickson told Space.com that it didn’t even really look like a crater anymore at the time of discovery. An older impact crater may be more difficult to spot since it would have been subjected to even more erosion over the years.

See also:
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