Re: Does the total amount of H2O on Earth, in various states, change?

Normally we assume that H2O reservoirs in the world are in a dynamic equilibrium -- water constantly moves in and out of a reservoir, but the total amount of water within the reservoir is constant. This is a good assumption for most applications, but if we consider the entire life span of the Earth, the assumption does not hold. For example, at the early stage, Earth was covered by ocean, and today ocean covers about 70% of Earth surface.

Given global warming, more water will evaporate from the ocean to the atmosphere as vapor. And if temperature of the atmosphere also increases, it will also be able to hold more moisture. This may change the distribution. However, on a global scale, this change, if any, has yet to be determined.

The attached figure shows the distribution of water at various reservoirs.