[sschueller]

But that 100 tons of water will convert a large amount of CO2 to O2 as the trees grow. Rocks don't capture any CO2.

[sirclueless]

I believe that number is purely the water used converting pulp into paper, not water consumed growing trees. I've heard it's 400 parts water and one part pulp, not sure how accurate that is.[1]

[1]: http://www.alternet.org/environment/whats-better-environment...