RE: In 20 years, water demand will exceed supply by 40 percent
Water is not and will not be in short supply on this planet. If any resource is recyclable, water is at the top. It goes in one end and out the other - in every system known to man! The problem for humans is - where do you reside in relation to your source for drinkable water? What percentage of the planet's surface is covered by water? Well, there may be several estimates. Again, the problem for humans (and most animals) is how to make sea water drinkable? The technology is here ... yes, it is expensive for large desalination systems but if comes to the point made in this article, I am sure we will find a way or live with it. Just look at what we live with now for the price of gasoline ... was $0.21 (thereabouts) and it is now $3.39 (again, thereabouts).
