Water on early Earth

The claim that Earth’s water is more than 2.7 billion years old likely understates the age of the evidence. Zircon studies indicate liquid water interacting with Earth’s crust at least 4.0 billion years ago, and some zircons point to water as early as about 4.4 billion years ago. These are geological traces of ancient water, not a way to date the exact water molecules in today’s oceans. The illustration is AI-generated.