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Biosphere

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Title: Biosphere  
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Biosphere

A false-color composite of global oceanic and terrestrial photoautotroph abundance, from September 1997 to August 2000. Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center and ORBIMAGE.

The biosphere is the global sum of all biogenesis (life created from living matter), at least some 3.5 billion years ago.[2][3] The earliest evidence for life on Earth includes biogenic graphite found in 3.7 billion-year-old metasedimentary rocks from Western Greenland[4] and microbial mat fossils found in 3.48 billion-year-old sandstone from Western Australia.[5][6] More recently, in 2015, "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia.[7][8] According to one of the researchers, "If life arose relatively quickly on Earth ... then it could be common in the universe."[7]

In a general sense, biospheres are any closed, self-regulating systems containing ecosystems. This includes artificial biospheres such as Biosphere 2 and BIOS-3, and potentially ones on other planets or moons.[9]

Contents

  • Origin and use of the term 1
    • Narrow definition 1.1
  • Extent of Earth's biosphere 2
  • Specific biospheres 3
  • Extraterrestrial biospheres 4
  • See also 5
  • References 6
  • External links 7

Origin and use of the term

The term "biosphere" was coined by geologist Eduard Suess in 1875, which he defined as the place on Earth's surface where life dwells.[10]

While the concept has a geological origin, it is an indication of the effect of both Charles Darwin and Matthew F. 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

A beach scene on Earth, simultaneously showing the lithosphere (ground), hydrosphere (ocean) and atmosphere (air)

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 word ecosphere, coined during the 1960s, encompasses 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. Others may include the creation of artificial non-Earth biospheres—for example, human-centered biospheres or a native Martian biosphere—as part of the topic of biospherics.

Extent of Earth's biosphere

Water covers 71% of the Earth's surface. Image is the Blue Marble photographed from Apollo 17.

Every part of the planet, from the polar ice caps to the equator, features life of some kind. 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 difficult to measure. Birds typically fly at altitudes of 650 to 1,800 metres, and fish that live deep underwater can be found down to -8,372 metres in the Puerto Rico Trench.[2]

There are more extreme examples for life on the planet: Rüppell's vulture has been found at altitudes of 11,300 metres; bar-headed geese migrate at altitudes of at least 8,300 metres; yaks live at elevations between 3,200 to 5,400 metres above sea level; mountain goats live up to 3,050 metres. Herbivorous animals at these elevations depend on lichens, grasses, and herbs.

Microscopic organisms live at such extremes that, taking them into consideration, the thickness of the biosphere is much greater. Culturable microbes have been found in the Earth's upper atmosphere as high as 41 km (25 mi).[11] It is unlikely, however, that microbes are active at such altitudes, where temperatures and air pressure are extremely minor and ultraviolet radiation very intense. More likely, these microbes were brought into the upper atmosphere by winds or possibly volcanic eruptions. Barophilic marine microbes have been found at more than 10 km (6 mi) depth in the Mariana Trench.[12] In fact, single-celled life forms have been found in the deepest part of the Mariana Trench, Challenger Deep, at depths of 36,201 feet (11,034 meters).[13] Microbes are not limited to the air, water or the Earth's surface. Culturable thermophilic microbes have been extracted from cores drilled more than 5 km (3 mi) into the Earth's crust in Sweden,[14] from rocks between 65-75 °C.

Temperature increases with increasing depth into the Earth's crust. The rate at which the temperature increases depends on many factors, including type of crust (continental vs. oceanic), rock type, geographic location, etc. The greatest known temperature at which microbial life can exist is 122 °C (Methanopyrus kandleri Strain 116), and it is likely that the limit of life in the "deep biosphere" is defined by temperature rather than absolute depth.

Our biosphere is divided into a number of homeothermy, estivation and multiple layers of insulation.

Specific biospheres

For this list, if a word is followed by a number, it is usually referring to a specific system or number. Thus:

  • Biosphere 1, the planet Earth.
  • Biosphere 2, laboratory in Arizona, United States, which contains 3.15 acres (13,000 m2) of closed ecosystem.
  • BIOS-3, a closed ecosystem at the Institute of Biophysics in Krasnoyarsk, Siberia, in what was then the Soviet Union.
  • Biosphere J (CEEF, Closed Ecology Experiment Facilities), an experiment in Japan.[15][16]

Extraterrestrial biospheres

No biospheres have been detected beyond the Earth; therefore, the existence of extraterrestrial biospheres remains hypothetical. The rare Earth hypothesis suggests they should be very rare, save ones composed of microbial life only.[17] On the other hand, Earth analogs may be quite numerous, at least in the Milky Way galaxy.[18] Given limited understanding of abiogenesis, it is currently unknown what percentage of these planets actually develop biospheres.

It is also possible that artificial biospheres will be created during the future, for example on Mars.[19] The process of creating an uncontained system that mimics the function of Earth's biosphere is called terraforming.[20]

See also

References

  1. ^
  2. ^ a b
  3. ^
  4. ^
  5. ^
  6. ^
  7. ^ a b
  8. ^ Early edition, published online before print.
  9. ^
  10. ^ Seuss, E. (1875) Die Entstehung Der Alpen [The Origin of the Alps]. Vienna: W. Braunmuller.
  11. ^ Wainwright et al, (2003). "Microorganisms cultured from stratospheric air samples obtained at 41 km." FEMS Microbiology Letters 218, 161-165.
  12. ^ Takamia et al (1997). "Microbial flora in the deepest sea mud of the Mariana Trench." FEMS Microbiology Letters 152 (2), 279-285.
  13. ^ National Geographic, 2005
  14. ^
  15. ^
  16. ^
  17. ^ P. Ward, D.E. Brownlee. 2000. Rare Earth: Why Complex Life Is Uncommon in the Universe
  18. ^ Space.com
  19. ^ R. Zubrin. 1996. The Case for Mars: The Plan to Settle the Red Planet and Why We Must
  20. ^

External links

  • Biosphere Definition
  • Article on the Biosphere at Encyclopedia of Earth
  • GLOBIO.info, an ongoing programme to map the past, current and future impacts of human activities on the biosphere
  • Paul Crutzen Interview, freeview video of Paul Crutzen Nobel Laureate for his work on decomposition of ozone talking to Harry Kroto Nobel Laureate by the Vega Science Trust.
  • Atlas of the Biosphere
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