Global warming is the increase of earth’s average temperature as the result of green house effect. Green house gases in the atmosphere act like a mirror reflecting back the heat radiation which would otherwise be dispersed into space. Greenhouse effect is the problem of gradual rise of gases such as carbon dioxide in the air surrounding the earth which traps the heat if the sun. Greenhouse gases are any of the gases that are thought to cause green house effect.
Carbon dioxide is the main green house gas. The gas contributes over 50% of green house effect. The following are some of the sources of carbon dioxide in the environment or the atmosphere.
The main human activities that contribute to global warming are the burning of fossils (coal, oil and natural gas). The burning of fossils creates carbon carbon dioxide in the atmosphere.
Also clearing and burning of vegetations, green plants especially woody plants, absorb carbon dioxide from the atmosphere and they use it to produce their own foods. When the wood dies the carbon dioxide will be released back in the atmosphere. So when We loose trees and forest there will be fewer trees to absorb the carbon dioxide.
However Methane seems to contribute more since many of the SADC communities depend on agriculture. Methane is from agriculture activities it’s released from wetlands. The emission of methane gas increase with increase in agricultural activities, since 1960’s the amount of methane in the air has increased by 1% per year. Methane is also produced during mining of coal, oil and when vegetation burnt. Methane molecules have life time of 10 years in the atmosphere. SADC will be much harder hit than developed countries, due to limited agricultural flexibility.
Chlorofluorocarbon (CFCs) the source of CFCs in the atmosphere include fridges, air conditional and aerosols. CFCs are extremely affecting green house gases. A CFC molecule is 10,000 times more effective in trapping heat than carbon dioxide.
Therefore the changing of the average global temperature by even one or two degrees can lead to serious consequences around the SADC communities. First for every degree Fahrenheit of warming we wan expect to see, 5-15% reduction in the yield of crops currently grown, 3-10% increase in the amount of rain falling during the heaviest precipitation events, which can increase flooding, 5-10% decrease in stream flow in some rive basins.
Global average temperatures have increased more than 1.4 degree Fahrenheit over last 100 years. Many of the extreme precipitation and heat events that we have seen in recent years are consistent with what we would expect give this amount of warming. The scientist predicts that the temperature will increase by 1.4 and 5.8 degrees by the year 2100.
Continued global warming could have many damaging effects. First harm the ocean life, through global warming the surface of the earth could become warmer, such as coral reef. High water temperature can cause damaging process called coral bleaching. When coral bleach they expel the algae that give them their color and nourishment. The coral turns white and unless the water temperature cools, they die. Added warmth also helps spread diseases that affect sea creatures.
Also threats to human health. Tropical diseases such as malaria and dengue, might spread to larger regions, longer lasting and more intensive floods could increase hunger and malnutrition.
While the sea level will also rise. Continued global warming might melt large amount of ice from the vast the sheet that covers most of the west Antarctica. As a result coastal areas would experience flooding, erosion a loss of wetlands and entry of seawater into fresh water areas. High sea level would submerge some coastal cities, Small Island and other inhabited regions.
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