Such changes in precipitation then serve to increase the frequency and intensity of extreme weather events like floods, droughts, heat waves, hurricanes and tornados. However, other scientists maintain that man and his carbon dioxide emissions are not solely to blame for the temperature changes, that prediction of these changes is has yet to become 100 percent accurate, and that the perceived temperature rise can never annihilate life on earth. This paper examines the clashing scientific opinions less for the purpose of determining which side presents the stronger arguments but more for drawing the information on the causes and effects of global warming.
The greenhouse effect theory postulates that the gases and carbon dioxide expelled by people through the burning of fossil fuels, land clearing and agriculture collect in the atmosphere and cause the earth's average temperature to rise (Whipple 12). According to this theory, the anthropogenic or manmade carbon dioxide released into the atmosphere in the past 400,000 years doubled since the Industrial Revolution, which was then helped along by the natural changes in the Earth's orbit around the sun to cause global warming (Taylor 8). Increase of such carbon dioxide in the atmosphere warms the Earth's surface and leads to the melting of polar ice caps. As the ice melts, land or open water appears in its place, neither of which is as reflective as ice and thus absorbs more solar radiation (Murray 6). This causes more warming and more melting. Thus, most scientists believe greenhouse gases are the primary cause of global warming such that human activity is entirely to blame for this phenomenon.
Indeed man is responsible for at least some of the greenhouse gases and carbon dioxide emissions, but many climate experts dispute the view that ascribes temperature changes to rising carbon dioxide levels. The US National Academy of Sciences took the same position when it declared in 2001 that the link between greenhouse emission and climate change cannot be established equivocally because of the "large and still uncertain level of natural variability" in the climate. If at all, only three-quarters of manmade emissions of CO2 during the past 20 years is due to fossil fuel burning, since the rest is due to atmospheric soot, land use changes, land clearing and agricultural activities, especially deforestation (Castles 5). Methane, a byproduct of natural gas, also enters the atmosphere from biological production and leaks from natural gas pipelines and similar structures (Castles & Henderson 9). Other biological sources of methane are not anthropogenic such as termites, and non-human causes include volcanic emissions and solar variations (Lee 43). In this view, the role of greenhouse gases in global warming has been overblown (Zwally 7).
The relationship between global warming and hurricanes is another subject that is hotly debated. If the world's climatic scientists agree on one thing, it is on the increasing force of recent hurricanes such as Hurricane Katrina, which swept the Americas and Europe in 2004. The consensus is that no natural calamity in memory matched the scope and magnitude of the damage Katrina wrought on lives, property and the economy. However, research by a group of German