Friday, October 2, 2009

GLOBAL WARMING

Global warming is the phenomenon resulting from the release and accumulation of carbon gases and other man-made contaminants in the Earth’s atmosphere. These heat-trapping gases act like a thick blanket, trapping the sun’s heat and causing the planet to warm up. As the gases increases, the Earth’s atmospheric temperature increases, too.
Climate change, on the other hand, refers to the variation in the Earth’s global climate or in regional climates over time. It describes changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years. In recent usage, especially in the context of environmental policy, the term “climate change” often refers only to changes in modern climate, including the rise in average surface temperature known as global warming.
It is clearly an environmental domino effect. Global warming increases water vapor in the air, which in turn absorbs more of the earth’s heat. Rising surface temperature melts polar snow and ice. Exposed ground absorbs more sunlight, which cause the melting of more snow. The oceans, on the other hand, store more heat extending the warming trend. Melting glacial ice then causes oceans to swell.
Five gases are responsible for the bulk of the greenhouse phenomenon: Carbon dioxide (emitted by burning fuels, vehicles, factories and biosphere destruction is responsible for more than 50 percent of global warming), CFC (used in refrigeration and air conditioning, aerosol, cosmetics and packaging accounts for around 20 percent of the warming), nitrous oxide (emitted by the rapid decomposition of humus after forest clearing, and the breakdown of chemical fertilizers), Low-level ozone (produced in car exhausts), and methane (from decomposing garbage and livestock waste).
Since the beginning of the industrial revolution in the 1850s, the naturally rising carbon dioxide levels are implicated as the primary cause of global warming a century after (1950) and continuing up to the present. According to the 2007 Intergovernmental Panel on Climate Change (IPCC), the atmospheric concentration of CO2 in 2005 was 379 parts per million (ppm) compared to the pre-industrial levels of 280 ppm. The present level (385 ppm) translates to 0.02 to 0.03 percent of the Earth’s atmosphere, which has been much higher in the long history of Earth. These increases are projected to reach more than 560 ppm before the end of the 21st century. Along with rising methane levels, these changes have been calculated to cause an increase of 1.4-5.6 °C between 1990 and 2100.
The IPCC concluded that most of the observed increase in average global temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic (man-made) greenhouse gas concentrations. Natural phenomena such as solar variation combined with volcanoes probably had a small warming effect from pre-industrial times to 1950 and a small cooling effect from 1950 onward. These basic conclusions have been endorsed by at least thirty scientific societies and academies, including all of the national academies of science of the major industrialized countries. While individual scientists have voiced disagreement with some findings of the IPCC, the overwhelming majority of scientists working on climate change agree with the IPCC’s main conclusions.
Deforestation is also one of the major causes of global warming. Each hectare of forest cover can absorb around eight tons of carbon dioxide every year. The earth’s forest ecosystem stores over 1.2 trillion tons of carbon dioxide that would otherwise pollute our atmosphere. In the last ten years alone, more than 25 billion tons of carbon dioxide were released into the atmosphere due to deforestation and land conversion.
Global warming is destructive to human civilization because it will cause increasingly severe weather events, significant changes to the amount and pattern of precipitation causing wider range of floods and droughts, and the melting of the glaciers which in turn will cause sea level to rise. Other expected effects of global warming include changes in agricultural yields, modifications of trade routes, species extinctions and increases in the ranges of disease vectors. Recent data culled from Antarctic ice cores indicates that atmospheric carbon dioxide concentrations are now higher than at any time during the past 650,000 years, which is as far back as measurements can now reach.

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