Oldest impact crater on Earth found and it could throw light on ancient climate change The extreme temperatures and pressures associated with an asteroid strike causes minerals to lose their accumulated lead, resetting the ‘clock’. So, by knowing the amount of uranium and how long it takes to decay, they calculated that the crater is 2.229 billion years old, plus or minus five million years. The team realised that the new, more precise date of the impact meant that most of Earth, including Australia, was covered with thick ice sheets at the time. They also realised the impact came shortly before the global ice age ended, when the Earth began to warm - at 2.225 billion years, plus or minus three million years. I admit the evidence "could" is ambiguous- however it's not ambiguous to know that man had no effect on the end of the Ice Age or the warming since then.