Biosphere

The biosphere is the highest level of organization of the Earth's biological activity. It processes matter and energy transfer with an efficiency of 10 percent across the Earth's atmosphere, lithosphere, hydrosphere, cryosphere, and anthrosphere. The atmospheric processes involve a vast number of chemical reactions and gas exchanges within the atmosphere. The hydrosphere consists of the Earth's water systems, needed for organisms living on the planet to survive. The geosphere and biosphere are closely connected through soils that consist of an admixture of air, mineral matter, organic matter, and water. The anthrosphere is the dimension of the biosphere that has been—and continues to be—altered by humans for human activities. The human population is now a direct threat to the biosphere through habitat destruction and atmospheric degradation, especially deforestation and greenhouse gas emissions. Human activities are recognized to be the cause of a mass extinction of other species and an ensuing depletion of genetic variation and biological diversity (biodiversity).

The biosphere encompasses all biological activity on Earth, which is of vital importance to the functioning of natural and human-engineered ecosystems, and by extension, the services that nature provides free of charge to human society. The value of these services to the human economy is so huge as to defy quantification, though ecological economists continue the effort to more fully account for costs of production endured by the biosphere as “ecosystem services.” The biosphere performs all biological functions, including photosynthesis, [Page 40]decomposition, nitrogen fixation, respiration, and denitrification. The biosphere is structured into a hierarchy of life-forms known as the food chain, in which all life evolves toward increasing complexity. The biosphere makes our planet unique among the planets in the solar system.

This image of Western Europe created by a NASA remote-sensing satellite is part of an attempt to capture information about the biosphere, such as vegetation cover, that may help scientists better understand changes on a global level.

Source: NASA

The history of the term biosphere goes back to 1875, when geologist Eduard Suess originated the term, defining it as “the place on earth's surface where life dwells.” Russian scientist Vladimir Vernadsky extended the term in 1929, refining its definition into a form resembling its current ecological sense in his obscure book The Biosphere, published in 1926. Thanks to Vernadsky's work, ecology was redefined as the science of the biosphere, and the biosphere concept began to occupy its current central position in Earth systems science.

The biosphere is studied within the scientific fields of biology and ecology. It exists as the highest level of biological organization, beginning with parts of cells and rising to populations, species, ecoregions, and biomes. Biomes describe global patterns of biodiversity within the biosphere's many ecosystems. Living organisms and their remains in the biosphere interact with the other spheres (above) in global biogeochemical cycles and energy budgets, as the biosphere plays it central part in the nurturing of life on Earth.

Researchers directly observe biosphere activity using global remote-sensing platforms, some dispersed on Earth's surface and many launched aboard remote-sensing satellites into near-Earth space over the past few decades. Direct observation has greatly benefited from advanced space-based remote-sensing systems, which are capable of scanning the entire Earth's surface at least once a day. These observations help determine the extent and amount of activity in the biosphere, mainly in terms of vegetation cover and function and characteristic spectrum responses in sensing spectrometers. More remote-sensing efforts in the future will directly observe global patterns of carbon dioxide exchange in the biosphere, caused by respiration, photosynthesis, greenhouse gas emissions, and the combustion of biomass and fossil fuels.

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