Biosphere

The biosphere is the part of Earth's outer shell – including land, surface rocks, water, and the atmosphere – within which life occurs. From the broadest geophysiological point of view, the biosphere is the global ecological system integrating all living beings and their relationships, including their interaction with the elements of the lithosphere (rocks), hydrosphere (water), and atmosphere (air). Currently the entire Earth contains over 75 billion tons of biomass (life), which lives within various environments within the biosphere.

Over nine-tenths of the total biomass on Earth is plant life, on which animal life depends very heavily for its existence. More than 2 million species of plants and animals have been identified to date, and the actual number of existing species ranges from several million to over 50 million. The number of individual species is constantly in some degree of flux, with new species appearing and others ceasing to exist on a continual basis. The total number of species is presently in rapid decline.

Biosphere is a relatively thin life-supporting layer around the Earth containing living organisms, which is strongly influenced in composition, structure and energetics by the living organisms. Part of the biosphere containing the highest concentration of living matter – the Earth’s thin and fragile “film of life” – varies from a few meters in deserts and tundra to a hundred meters in tropical forest regions and oceans.

The biosphere is a complex system of energy use and material cycling. This system runs on energy flowing into it from the Sun and gives off energy (primarily as heat) to space.

We can divide the biosphere into two parts, living and nonliving, or biotic and abiotic. The biotic part of the biosphere consisting of fauna and flora is called biota.

The idea of biosphere originated rather casually more than a century ago. It was Edward Suess, an Austrian who proposed the term biosphere after observing that life only developed within the strict limits of earth’s part that makes up the atmosphere, hydrosphere and lithosphere. The concept played little part in scientific thought, however, until it was developed by the Russian scientist V.I. Vernadsky. It is essentially his concept of the biosphere that we accept today.