The biosphere is the largest possible earthly organismic community. It is a terrestrial envelope of life, or the total global biomass of living matter. The biosphere incorporates every individual organism and species on the face of the earth—those that walk on the ground or live in the crevices of rock and down into the soil, those that swim in rivers, lakes, and oceans, and those that move in and out of the atmosphere.

Bios is the Greek word for life; "sphere" is from the Latin sphaera, which means essentially the "circuit or range of action, knowledge or influence," the "place or scene of action or existence," the "natural, normal or proper place." Combined into biosphere, the two ideas define the normal global place of existence for all earthly life-forms and, increasingly, a global area of influence and action for humans. Thinking of the mass of life forms...