Question

Is the amount of water on our planet is the same today as it was 5,000 years ago. How do we know?

Answer 1

Water has an infinite cycle of ocean to rain and back to the ocean. Water cannot leave this cycle unless brought to space by people. So there should be roughly the same amount of water on the Earth now as there was 5,000 years ago.

Answer 2

Water flows endlessly between the ocean, atmosphere, and land. Earth's water is finite, meaning that the amount of water in, on, and above our planet does not increase or decrease.