Biosphere
Relatively thin life-supporting stratum of the earth's surface, extending from a few miles into the atmosphere to the deep-sea vents of the oceans.
 |
| Biosphere |
The biosphere is a global ecosystem that can be broken down into regional or local ecosystems, or biomes. Organisms in the biosphere are classified into trophic levels (see food chain) and communities.
Biodiversity
Quantity of plant and animal species found in a given environment.
 |
| Biodiversity |
Sometimes habitat diversity (the variety of places where organisms live) and genetic diversity (the variety of traits expressed within a species) are also considered types of biodiversity. The estimated 3–30 million species on Earth are divided unequally among the world's habitats, with 50–90% of the world's species living in tropical regions. The more diverse a habitat, the better chance it has of surviving a change or threat to it, because it is more likely to be able to make a balancing adjustment. Habitats with little biodiversity (e.g., Arctic tundra) are more vulnerable to change. The 1992 Earth Summit resulted in a treaty for the preservation of biodiversity.
Global Warming
Increase in the global average surface temperature resulting from enhancement of the greenhouse effect, primarily by air pollution.
 |
| Earth Climate Change |
In 2007 the UN Intergovernmental Panel on Climate Change forecasted that by 2100 global average surface temperatures would increase 3.2–7.2 °F (1.8–4.0 °C), depending on a range of scenarios for greenhouse gas emissions, and stated that it was now 90 percent certain that most of the warming observed over the previous half century could be attributed to greenhouse gas emissions produced by human activities (i.e., industrial processes and transportation).
Many scientists predict that such an increase in temperature would cause polar ice caps and mountain glaciers to melt rapidly, significantly raising the levels of coastal waters, and would produce new patterns and extremes of drought and rainfall, seriously disrupting food production in certain regions. Other scientists maintain that such predictions are overstated. The 1992 Earth Summit and the 1997 Kyoto Protocol to the United Nations Framework Convention on Climate Change attempted to address the issue of global warming, but in both cases the efforts were hindered by conflicting national economic agendas and disputes between developed and developing nations over the cost and consequences of reducing emissions of greenhouse gases.
Air Pollution
Release into the atmosphere of gases, finely divided solids, or finely dispersed liquid aerosols at rates that exceed the capacity of the atmosphere to dissipate them or to dispose of them through incorporation into the biosphere.
 |
| Air pollution |
Dust storms in desert areas and smoke from forest and grass fires contribute to particulate and chemical air pollution.
Volcanic activity is the major natural source of air pollution, pouring huge amounts of ash and toxic fumes into the atmosphere.
Air pollution may affect humans directly, causing irritation of the eyes or coughing. More indirectly, its effects can be measured far from the source, as, for example, the fallout of tetraethyl lead from automobile exhausts, which has been observed in the oceans and on the Greenland ice sheet. Still less direct are possible effects on global climates.
EarthSummit
officially United Nations Conference on Environment and Development
Conference held in Rio de Janeiro (June 3–14, 1992) to reconcile worldwide economic development with environmental protection.
 |
| Reo de janeiro 1992 |
It was the largest gathering of world leaders in history, with 117 heads of state and representatives of 178 countries. Biodiversity, global warming, sustainable development, and preservation of tropical rain forests were among the topics discussed. Five international agreements were signed amid tensions between the industrialized countries of the North and the poorer developing states of the South, who were reluctant to accept environmental restrictions without increased Northern economic aid.
Follow-up meetings were held in 1997 at the UN General Assembly in New York and in 2002 in Johannesburg, S.Af. See also Rio Treaty.
Rio De Janeiro Treaty
officially Convention on Biological Diversity
International environmental agreement approved at the 1992 Earth Summit in Rio de Janeiro.
Negotiations began in 1988 under the auspices of the United Nations Environment Program. Its goals are the conservation of the planet's biodiversity and the fair use of its resources. By the early 21st century, more than 185 governments were party to the agreement.
Green house effect
Warming of the Earth's surface and lower atmosphere caused by water vapour, carbon dioxide, and other trace gases in the atmosphere.
Art:Some incoming sunlight is reflected by the Earth's atmosphere and surface, but most is absorbed by …
 |
| greeen house effect |
* Some incoming sunlight is reflected by the Earth's atmosphere and surface, but most is absorbed by …
-
Green House Effect
Visible light from the Sun heats the Earth's surface. - Part of this energy is radiated back into the atmosphere in the form of infrared radiation, much of which is absorbed by molecules of carbon dioxide and water vapour in the atmosphere and reradiated toward the surface as more heat. (Despite the name, the greenhouse effect is different from the warming in a greenhouse, where panes of glass allow the passage of visible light but hold heat inside the building by trapping warmed air.)
- The absorption of infrared radiation causes the Earth's surface and lower atmosphere to warm more than they otherwise would, making the Earth's surface habitable. An increase in atmospheric carbon dioxide caused by widespread combustion of fossil fuels may intensify the greenhouse effect and cause long-term climatic changes.
- Likewise, an increase in atmospheric concentrations of other trace greenhouse gases such as chlorofluorocarbons, nitrous oxide, and methane resulting from human activities may also intensify the greenhouse effect.
- From the beginning of the Industrial Revolution through the end of the 20th century, the amount of carbon dioxide in the atmosphere increased 30% and the amount of methane more than doubled. It is also estimated that the U.S. is responsible for about one-fifth of all human-produced greenhouse-gas emissions. See also global warming.
Eco system
Complex of living organisms, their physical environment, and all their interrelationships in a particular unit of space.
An ecosystem's abiotic (nonbiological) constituents include minerals, climate, soil, water, sunlight, and all other nonliving elements; its biotic constituents consist of all its living members.
Two major forces link these constituents: the flow of energy and the cycling of nutrients. The fundamental source of energy in almost all ecosystems is radiant energy from the sun; energy and organic matter are passed along an ecosystem's food chain. The study of ecosystems became increasingly sophisticated in the later 20th century; it is now instrumental in assessing and controlling the environmental effects of agricultural development and industrialization. See also biome.
Biome
Largest geographic biotic unit, a major community of plants and animals with similar requirements of environmental conditions.
It includes various communities and developmental stages of communities and is named for the dominant type of vegetation, such as grassland or coniferous forest. Several similar biomes constitute a biome type; for example, the temperate deciduous forest biome type includes the deciduous forest biomes of Asia, Europe, and North America. The standard European term for biome is “major life zone.”
