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Increase in the global average surface temperature resulting from enhancement of the greenhouse effect, primarily by air pollution. In 2007 the UN Intergovernmental Panel on Climate Change forecasted that by 2100 global average surface temperatures would increase 3.27.2 °F (1.84.0 °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.
Grape (Vitis).Grant Heilman PhotographyAny of the 60 plant species that make up the genus Vitis (family Vitaceae), native to the northern temperate zone, including varieties that may be eaten as table fruit, dried to produce raisins, or crushed to make grape juice or wine. V. vinifera is the species most commonly used in wine making. The grape is usually a woody vine, climbing by means of tendrils. In arid regions it may form an almost erect shrub. Botanically, the fruit is a berry. Grapes contain such minerals as calcium and phosphorus and are a source of vitamin A. All grapes contain sugar (glucose and fructose) in varying quantities depending on the variety.
Alcoholic beverage made from the fermented juice of grapes. Wine may also be made from various fruits and plant parts. Though known by the ancients, wine was not drunk in its matured form until the development of the bottle and cork in the late 17th century. In wine manufacture, grapes are crushed and strained, and the juice (called must) is sealed in vats along with yeast (Saccharomyees ellipsoideus) and often sulfur dioxide, which suppresses wild yeasts and organisms. Fermentation continues for several weeks, and then the wine is drawn off (racked) into wooden barrels or other containers for a second fermentation (aging). It is clarified and bottled before undergoing final maturation. Wines may be classified according to colour as red, rosé (pink), or white; colour depends on whether the skins of red grapes are allowed to ferment with the juice. Wine taste is described as sweet or dry, sweet wines being high in sugar content and dry wines containing little or no sugar. Sparkling wines, such as champagne, contain suspended carbon dioxide, the result of bottling the wine before fermentation is complete. Fortified wines, such as port and sherry, contain added brandy. The leading wine-producing countries are France, Italy, Spain, the U.S., Argentina, Germany, Australia, South Africa, Portugal, and Romania.
© 2010 Encyclopædia Britannica, Inc.


