Oceanic crust is more dense which makes it subduct and continental crust is less dense which makes it override the oceanic crust during subduction
Global water supply is currently a troubling issue. The world's population size is steadily increasing, without the increase in water supply, leaving many to fear an impending shortage.
Freshwater is not evenly distributed across the globe and desalination of water is one solution put forth, but it also comes with its own challenges such as: being very expensive, requiring large amounts of energy, harsh impact on marine life, water being a commodity controlled by large corporations, and emissions having a harsh effect on environments.
