Upon combustion, fossil fuels like coal and petroleum release green house gases like carbon dioxide. As the quantity of carbon dioxide increases in the atmosphere, the atmosphere becomes a much better insulator and retains an increased amount of solar radiation which in turn increases the overall temperature of the planet. Many scientists believe that the release of carbon dioxide and certain other substances into the air are affecting the earth's climate and causing the average global temperature to rise. There is evidence that the earth's temperature has risen in the past century, but scientists are unable to predict with certainty whether this trend will continue or whether it is definitely linked to human activity.
Global warming has many affects. As the temperature increases, there is a possibility of melting of polar glaciers and ice caps. The resulting water would flow into the oceans and increase the volume of the oceans. This would lead to rise of ocean levels. Scientists estimate that the sea level could rise from any where between 9 to 88 centimeters (Hart 2003). Such an increase would submerge low lying coastal areas in many countries of the world. Global warming also affects human health. If the atmospheric temperature is increased due to global warming, more people will get sick or die from heat stress. This may be more due warmer nights, giving the sufferers less relief than due to heat during the day time. There is also a possibility of diseases spreading to new regions. Diseases now found in the tropics, transmitted by mosquitoes and other animal hosts, will widen their range as these animal hosts move into regions formerly too cold for them. Today 45 percent of the world's people live where they might get bitten by a mosquito carrying the parasite that causes malaria; that percentage may increase to 60 percent if temperatures rise (Mastrandrea and Shneider 2003). Other tropical diseases may spread similarly, including dengue fever, yellow fever, and encephalitis. Scientists also predict rising incidence of allergies and respiratory diseases as warmer air grows more charged with pollutants, mold spores, and pollens.
Heat stress or heat prostration is a condition that is produced by over exertion in hot temperatures. It occurs when the person is subjected to high temperatures or extreme hot dryness.
When the body undergoes physical exertion, it perspires which produces sweat. The sweat evaporates to cool the skin and prevents body temperature from rising. Perspiration causes the loss of fluids and salts normally replaced by regularly consuming liquids and food. However, if prolonged, excessive sweating occurs, fluids and salts are not replaced rapidly enough resulting in increase in the viscosity of blood. This causes blood circulation to diminish, affecting the brain, heart, and lungs, and heat exhaustion results.
Symptoms of heat exhaustion include heavy sweating; pale, clammy skin; dilated pupils; a slightly elevated body temperature; and cramps, weakness, dizziness, nausea, vomiting, headache, mental confusion, and sometimes unconsciousness.
Heat stress and global warming
Incidence of heat stress increases with temperature. Hence the number of cases of incidence of heat stress tends to increase in the very near future due to rise in temperatures