The greenhouse effects
Most people mistakenly held the notion that greenhouse effect is bad because of its association with global warming, but the truth is we couldn’t live without it. The greenhouse effect by itself is a natural process that maintains the Earth’s temperature at levels hospitable to life. Greenhouse gases, composing primarily of water vapor, carbon dioxide, methane and nitrous oxide, made up about 1% of the atmosphere. As the Earth radiates the heat from the sun back into the space, these gases reflect enough heat back to maintain the average atmospheric temperature at around 60 degree Fahrenheit; without the greenhouse effect, the Earth would be a cold, inhospitable place.
A simple analogy to understand greenhouse effect is to think of a car parked outside on a sunny day; after a while, the inside of the car will be much hotter. As the sun rays enter through the car’s windows, some of the heat is absorbed by the seats, dashboard, carpeting and floor mats. When this heat is released, some is reflected back in because the heat radiated is a different wavelength than the initial ray that made it through the windows in the first place. Certain amount of energy is going in, and less energy is going out; the result is a gradual increase in the temperature inside the car.
The earth’s climate has been alternating between hot (interglacial) and cold periods (ice ages) for at least the past million years, as showed by polar ice cores records. The issue is really the humankind’s role in enhancing the greenhouse effect to a level more than necessary that contributed to global warming. The observed warming since the 1970’s cannot be explained by natural causes alone; most of the warming in the past 50 years can be attributed to the increase in greenhouse gas concentrations from human activities such as the burning of fossil fuels and land use change. The supply and use of fossil fuels accounts for about three quarter of carbon dioxide’s emissions, generated during combustion from automobiles engines and industrial activities. Methane, the second most important greenhouse gas, is emitted in farming practices and during decomposition of biomass and animal manure; about one quarter of global methane emissions comes from agricultural activities. Destruction of forests further aggravates the problem as fewer trees are available to utilize the carbon dioxide to create an optimal balance of gases in the atmosphere. Population growth is another factor in global warming; more people means increased level of greenhouse gases as human activities increases.
The earth’s climate is a finely balanced system; a small rise in atmospheric temperature could produce changes to the climate worldwide. As a result, the enhanced greenhouse effect is often referred to as climate change or global warming. At present, the earth’s temperature is increasing with unprecedented speed at present. The average global temperature increased by about 0.6 degrees Celsius, which is slightly more than 1 degree Fahrenheit, during the entire 20th century. Using computer climate models, scientists estimate that by the year 2100 the average global temperature will increase by 1.4 degrees to 5.8 degrees Celsius, approximately 2.5 degrees to 10.5 degrees Fahrenheit.
The mounting evidence about the enhanced greenhouse effect and its potential consequences prompted 160 countries around the world to sign the United Nations Framework Convention on Climate Change (UNFCCC) in 1992 which aims to stabilize the atmospheric greenhouse gases concentrations at a level that would prevent the global climate system from dangerous anthropogenic interference.
