The dictionary defines the greenhouse effect as the effect produced as greenhouse gases allow incoming solar radiation to pass through the Earth's atmosphere, but prevent most of the outgoing infrared radiation from the surface and lower atmosphere from escaping into outer space. According to the National Academy of Sciences, the Earth's surface temperature has risen about 1 degree Fahrenheit in the past century, with the acceleration warming during the past 2 decades. There is new and stronger evidence that most of the warming over the last 50 years is attributed to human activities. Human activities have altered the chemical composition of the atmosphere through the buildup of greenhouse gases - primarily carbon dioxide, methane, and nitrous oxide. The heat-trapping property of these gases is undisputed although uncertainties exist about exactly how earth's climate responds to them. (www.epa.gov).
Causes of Global Warming.
Although the causes of global warming are widespread, experts feel that the leading cause is that of overcrowding on the planet. Even though there are just over 5 billion human beings now, that number is expected to double in the next 60 years. More people means more energy, driving more miles, and producing more garbage. (Stegar/Bowermaster 1990) Even though this process occurs naturally and has kept the Earth's temperature about 60 degrees Fahrenheit warmer than it would be otherwise be, current life on Earth could not be sustained without the natural greenhouse effect. Some greenhouse gases occur naturally in the atmosphere, while other result from human activities. Naturally occurring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Certain human activities, however, add to the levels of most of these naturally occurring gases. CARBON DIOXIDE is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned.
