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Biosphere
Author: From Wikipedia
Biosphere
The biosphere is that part of a planet earth's outer shell-including air,
land, and water-within which life occurs, and which biotic processes in turn
alter or transform. 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). Earth is the only place where life is known
to exist. This biosphere is generally believed to have evolved beginning at
least some 3.5 billion years ago.
The term "biosphere" was coined by geologist Eduard Suess in 1875.
The concept thus has a geological origin and is an indication of the impact
of Darwin 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. The biosphere is an important
concept in astronomy, geophysics, meteorology, biogeography, evolution, geology,
geochemistry, and, generally speaking, all life and earth sciences.
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 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.
The Second International Conference on Closed Life Systems defined biospherics
as the science and technology of analogs and models of Earth's biosphere; i.e.,
artificial Earth-like biospheres. Some also include the creation of artificial
non-Earth biospheres-for example, human-centered biospheres or a native Martian
biosphere-in the field of biospherics.
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 concept that the biosphere is itself a living organism, either actually
or metaphorically, is known as Gaia theory.
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