Greenhouse Effect and Global Warming

Chan Shek Kiu - Professor at the School of Arts, Letters & Sciences; Coordinator, Center of Research in the Environmental Sciences and Center of Research in the Health Sciences (IIUM).

Everyone has heard the term greenhouse effect or global warming. It means that the average global air temperature will increase several degrees because of an increase in carbon dioxide (CO2) and other greenhouse gases in the Earth’s atmosphere. Since 1860 there has been a rise in temperature of roughly two-thirds of a degree Celsius, consequently, most scientists acknowledge that global warming exists.
The theory behind global warming is that the incoming sunlight (UV, visible light, infrared) heats up the Earth’s surface, but at the same time, the Earth cools itself off by emitting infrared radiation. The outgoing infrared, absorbed by carbon dioxide and other gases (greenhouse gases) in the atmosphere, is either re-emitted, or converted into heat. As a result, the greenhouse effect and global warming occurs.
The greenhouse gases consists of carbon dioxide (CO2), chlorofluorocarbons (CFCs) (compounds of chlorine, fluorine and carbon) and their replacements, methane (CH4), nitrous oxide (N2O), ozone (O3), water vapor, and airborne particles. They are produced in the following:
Industrial activities: carbon dioxide, particulate matters, photochemically reactive hydrocarbons (compounds of hydrogen and carbon), chlorofluorocarbons, besides sulfur dioxide (SO2), toxic heavy metals.
Fossil fuels burning: carbon dioxide, nitrogen oxides, methane, particulate soot, fly ash, in addition to carbon monoxide (CO), SO2, polycyclic aromatic hydrocarbons.
Transportation: carbon dioxide, nitrogen oxides, methane, beside carbon monoxide and polycyclic aromatic hydrocarbons.
Land surface alteration: e.g. deforestation. Burning of biomass and vegetation along with tropical and subtropical forests: carbon dioxide, nitrogen oxides, particulate soot, and polycyclic aromatic hydrocarbons.
Agricultural practices: methane from the digestive tracts of domestic animals and from rice in waterlogged anaerobic soils, nitrous oxides from bacterial denitrication (removal of nitrogen) of nitrate (NO3-)-fertilized soils.
The major effects of the above activities have been an increase of acidity in the atmosphere, which means rain is acidic. As a result, there will be increased corrosion of material, due to atmospheric pollutants. There is a production of pollutant oxidants in the lower troposphere and an increase of greenhouse gases. As there is a decrease of the ozone layer in the stratosphere, we are then exposed to more ultra-violet (UV) radiation because the ozone absorbs part of the UV from the sun. In consequence, there may be more skin cancer.
Besides the rise in global air temperature, there are other signs of the greenhouse effect and global warming. For instance, winters have become shorter, by about 11 days: spring comes earlier and autumn starts later in the Northern Hemisphere. The Earth’s ice cover is shrinking quickly. Glaciers, polar ice caps, and polar sea ice are vanishing at unprecedented rates. The warmer water is killing much of the coral in ocean reefs and threatening sea life. Over 95 percent of the coral in the Seychelles Islands has died! Mosquito-borne diseases have reached higher altitudes (e.g. malaria is found in higher mountain regions in Africa. Dengue fever occurs in new regions in Central America). The sea water level is rising and engulfing Pacific islands. The average sea level has risen about 10cm since 1940. Precipitation has increased in most regions. As temperature rises, evaporation becomes faster, and the water content in the atmosphere increases. Consequently, there will be more precipitation, in terms of rain and snow. Finally, extreme weather is becoming more common, producing stronger blizzards, storms, heavier snow, freezing rain, hurricanes, drought, etc.
Is it not time for us to do something?

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