Yarrabubba crater 2.229 billion years old

It's possible that the impact led to a great thaw as Earth exited a global frozen state.

More than two billion years ago, an asteroid slammed into Earth and created a 43-mile wide crater in Western Australia's outback. Researchers believe it is the oldest known impact crater, predating others by 200 million years. The new age of the Yarrabubba crater, created by dating the minerals, is 2.229 billion years old.

An impact into an ice-covered continent could have sent half a trillion tons of water vapor, an important greenhouse gas, into the atmosphere. Water vapor is an effective, and the most abundant, greenhouse gas that can absorb radiation and send it back to Earth's surface. The asteroid strike that led to the extinction of the dinosaurs 66 million years ago led to global ocean cooling and widespread acid rain.