• 1 Origin and use of the term
  • 1.1 Narrow definition
  • 1.2 Gaia's biosphere
• 2 Extent of the earth's biosphere
• 3 Biosphere 1, Biosphere 2, Biosphere 3
  • 3.1 Biosphere 1
• 4 See also
• 5 External links

Origin and use of the term

The term "biosphere" was coined by geologist Eduard Suess in 1875. While this concept has a geological origin, it is an indication of the impact of both Darwin and Maury on the earth sciences. The biosphere's ecological context comes from the 1920s (see Vladimir I. Vernadsky), preceding the 1935 introduction of the term "ecosystem" by Sir Arthur Tansley (see ecology history). Vernadsky defined ecology as the science of the biosphere. It is an interdisciplinary concept for integrating astronomy, geophysics, meteorology, biogeography, evolution, geology, geochemistry, hydrology and, generally speaking, all life and earth sciences.

Narrow definition

Some life scientists and earth scientists use biosphere in a more limited sense. For example, geochemists define the biosphere as being the total sum of living organisms (the "biomass" or "biota" as referred to by biologists and ecologists). In this sense, the biosphere is but one of four separate components of the geochemical model, the other three being lithosphere, hydrosphere, and atmosphere. The narrow meaning used by geochemists is one of the consequences of specialization in modern science. Some might prefer the word ecosphere, coined in the 1960s, as all encompassing of both biological and physical components of the planet.

Gaia's biosphere

The concept that the biosphere is itself a living organism, either actually or metaphorically, is known as Gaia theory.

Extent of the earth's biosphere

Some theorists have postulated that the Earth is poorly suited to life, although nearly every part of the planet, from the polar ice caps to the Equator, supports life of some kind. Indeed, recent advances in microbiology have demonstrated that microbes live deep beneath the Earth's terrestrial surface, and that the total mass of microbial life in so-called "uninhabitable zones" may, in biomass, exceed all animal and plant life on the surface. The actual thickness of the biosphere on earth is hard to measure. Birds typically fly at altitudes of 650 to 2000 meters, and fish that live deep underwater can be found down to -8,372 meters in the Puerto Rico Trench.

Biosphere 1, Biosphere 2, Biosphere 3

When the word Biosphere is followed by a number, it is usually referring to a specific system. Thus:

Biosphere 1

Our biosphere is divided into a number of biomes, inhabited by broadly similar flora and fauna. On land, biomes are separated primarily by latitude. Terrestrial biomes lying within the Arctic and Antarctic Circles are relatively barren of plant and animal life, while most of the more populus biomes lie near the Equator. Terrestrial organisms in temperate and arctic biomes have relatively small amounts of total biomass, smaller energy budgets, and display prominent adaptations to cold, including world-spanning migrations, social adaptations, homeothermy, estivation and multiple layers of insulation.

See also

• Lithosphere
• Earth's atmosphere
• Hydrosphere