The troposphere is the lower part of the atmosphere, of about 10-15 kilometres thick. Within the troposphere there are gasses called greenhouse gasses. When sunlight reaches the earth, some of it is converted to heat. Greenhouse gasses absorb some of the heat and trap it near the earth's surface, so that the earth is warmed up. This process, commonly known as the greenhouse effect, has been discovered many years ago and was later confirmed by means of laboratory experiments and atmospheric measurements.Life as we know it exists only because of this natural greenhouse effect, because this process regulates the earth's temperature. When the greenhouse effect would not exist, the whole earth would be covered in ice.The amount of heat trapped in the troposphere determines the temperature on earth. The amount of heat in the troposphere depends on concentrations of atmospheric greenhouse gasses and the amount of time these gasses remain in the atmosphere. The most important greenhouse gasses are
carbon dioxide, CFC's (Chlor-Fluoro-Carbons), nitrogen oxides and
methane.Since the industrial revolution in 1850 began, human processes have been causing emissions of greenhouse gasses, such as CFC's and carbon dioxide. This has caused an environmental problem: the amounts of greenhouse gasses grew so extensively, that the earth's climate is changing because the temperatures are rising. This unnatural addition to the greenhouse effect is known as global warming. It is suspected that global warming may cause increases in storm activity, Melting of ice caps on the poles, which will cause flooding of the inhabited continents, and other environmental problems.
Together with hydrogen, carbon dioxide is the main greenhouse gas. However, hydrogen is not emitted during industrial processes. Humans do not contribute to the hydrogen amount in the air, this is only changing naturally during the hydrological cycle, and as a result it is not a cause of global warming.Increasing carbon dioxide emissions cause about 50-60% of the global warming. Carbon dioxide emissions have risen from 280 ppm in 1850 to 364 ppm in the 1990s.
In the previous paragraph various human activities that contribute to the emission of carbon dioxide gas have been mentioned. Of these activities fossil fuel combustion for energy generation causes about 70-75% of the carbon dioxide emissions, being the main source of carbon dioxide emissions. The remaining 20-25% of the emissions are caused by land clearing and burning and by emission from motor vehicle exhausts.
Most carbon dioxide emissions derive from industrial processes in developed countries, such as in the United States and in Europe. However, carbon dioxide emissions from developing countries are rising. In this century, carbon dioxide emissions are expected to double and they are expected to continue to rise and cause problems after that.
Carbon dioxide remains in the troposphere about fifty up to two hundred years.
The first person who predicted that emissions of carbon dioxide from the burning of fossil fuels and other burning processes would cause global warming was Svante Arrhenius, who published the paper "On the influence of
carbonic acid in the air upon the temperature of the ground" in 1896.In the beginning of the 1930 it was confirmed that atmospheric carbon dioxide was actually increasing. In the late 1950s when highly accurate measurement techniques were developed, even more confirmation was found. By the 1990s, the global warming theory was widely accepted, although not by everyone. Whether global warming is truly caused by increasing carbon dioxide in the atmosphere, is still debated.
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