Photo of Kaieteur Falls, Guyana, by Graham Watkins

Biosphere: the planetary ecosystem – all parts of the Earth where life occurs, comprising the atmosphere, oceans, fresh waters, soils, and their underlying sediments and rock layers.  The word can be traced back to Eduard Suess and Vladimir Vernadsky in the late 19th and early 20th centuries, but has since come to overlap strongly with the concept of Gaia in the works of James Lovelock.  It is a central concept in Earth Systems Science.