At present 146 million people - concentrated in areas with scarce water and poor hygiene - are affected.

Sugar cane is particularly bad because it uses a lot a scarce water.

"With water so scarce, you'd think there'd be more people around a lake," Ayrlyn added.

They also take over pastoral grasslands and suck up scarce water.

Environmental scholars argue that scarce water and land will drive nations to battle.

Others take or exploit Palestinian resources, including scarce water and even the land itself.

Less dramatic, but just as important, scarce water resources must be fairly apportioned.

That's a huge allocation of land and scarce water to an enterprise of such low value.

It also takes over pastoral grasslands and uses scarce water.

With water so scarce, life in the Richtersveld depends on moisture from the early morning fog.