The earth's climate depends on the planet's receiving and disposing of energy from the sun. In actual fact except for a small fraction of heat from its inner core, all energy received at the earth's surface originates from the sun. Only about one two-billionth of this energy heats the earth, drives the oceans, and creates weather patterns thereby creating an atmosphere that is suitable and conducive for nature and the existence of living creatures.
Before the industrial revolution, human activities released very few gases into the atmosphere. However, during the industrial revolution, we began altering our climate and environment through changing agricultural and industrial practices. Now through population growth, fossil fuel burning, and deforestation, we are affecting the mixture of gases in the atmosphere, invariably leading to global warming.
Global warming can be defined as the progressive gradual rise of the earth’s surface temperature due to the increases of water vapour and other green house gases being released into the atmosphere by emissions from automobile, power plants, burning of fossil fuels, bi-products of industrial activities and other emissions.
A greater concentration in these gases in the atmosphere is believed to result in an enhancement of the greenhouse effect by trapping the sun’s heat in the earth’s atmosphere. (1) This enhanced green house effect causes the atmosphere to absorb and remit long wave length terrestrial infrared radiation.
Production of the green house gases by humans
The following human activities have been identified in the production of the following green house gases respectively:
a. Carbon dioxide (CO2).
Carbon dioxide is released to the atmosphere when solid waste, fossil fuels (oil, natural gas, and coal), and wood and wood products are burned. Carbon-dioxide is the main contributor to the green house effects. Deforestation has been found to be a major contributor because trees which fix carbon from the air are destroyed.
b. Methane (CH4)
Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills, and the raising of livestock.
c. Nitrous oxide (N2O)
This is emitted during agricultural and industrial activities, as well as during combustion of solid waste and fossil fuels.
d. Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6)
These are very powerful greenhouse gases that are not naturally occurring but are generated in a variety of industrial processes.
Each greenhouse gas differs in its ability to absorb heat in the atmosphere. HFCs and PFCs are the most heat-absorbent. Methane traps over 21 times more heat per molecule than carbon dioxide, and nitrous oxide absorbs 270 times more heat per molecule than carbon dioxide. Often, estimates of greenhouse gas emissions are presented in units of millions of metric tons of carbon equivalents (MMTCE), which weights each gas by its GWP value, or Global Warming Potential. (2)
Scientists generally agree that the earth has warmed by about 10 F in the past 140 years. If we continue to burn fossil fuels at the current rate, global temperatures may increase up to 630 F by 2100, sea level may rise by as much as 50cm by same year, the entire South Pacific Island nations may be swamped and millions of people living in low lying coastal nations such as Bangladesh could be displaced by this rising sea level. (1, 3)
Global warming has caused some devastation to health in the recent past. For example, in May 2002 temperature in the state of André Pradesh, India rose to 49 degree centigrade. This resulted in the highest one week mortality on record. Other countries that have experienced high temperatures with subsequent death toll are Nepal, Peru, Taiwan, Afghanistan, Tibet, Mongolia, South and Middle East, Denmark, Germany, central England, Austria, France and Australia.
Health effects of global warming to humans include:
1. More frequent heat waves, which will cause more heat stress deaths. In August 2003 for example, more than 11,400 people were killed in France by sudden heat wave.(4)
2. Increase in mortality from coronary heart disease and stroke
3. Decrease in water quality and quantity. This will result into people being more susceptible to water borne diseases such as cholera, and other diarrhoeal diseases.
4. Flood as a result of rise in sea levels. This will lead to destruction of life and properties as well as internal displacement. Flooding will also result in pollution of coral reefs. Destruction of aquatic life will also deplete aquatic source of nutrients.
5. Increase in the occurrence of highly destructive hurricanes. Although it is not yet clear whether more or fewer hurricanes will occur in the future with global warming, the hurricanes that do occur near the end of the 21st century are expected to be stronger and have significantly more intense rainfall than under present day climate conditions. According to a recent publication, greenhouse-gas induced warming may lead to a gradually increasing risk in the occurrence of highly destructive category-5 storms. (5) Morbid consequences of hurricane cannot be overemphasized. The devastation of the recent occurrence in the Caribbean and parts of the United States readily come to mind.
6. Increase in the incidence of vector borne diseases in tropical regions and emergence of these vector diseases such as malaria, dengue and yellow fever in countries where hitherto they are not in existence.
7. Drought. This is as a result of changes in the pattern of rainfall leading to desertification. A significant rise in temperature level (more than 2-3° C) could lead to a global decrease in food production, and even small increases in temperature will lead to decreased agricultural production in the tropics and sub-tropics, where there is hunger and famine today already by as much as 40%. (6) Mothers and children are worst hit, as there will be increased prevalence of malnutrition. Subsequently, maternal, infant and under-five mortality will increase.
Conclusions and Recommendations
It is clear from population studies that global energy needs will increase as 2 billion people are added to the world by 2030, mostly in developing countries. While we can't stop climate change, we can slow it down and adapt to this inevitable occurrence. The global challenge is to produce and use energy from fossil fuels more efficiently or without emitting carbon dioxide into the air; produce energy from renewable energy technologies such as wind and the sun; streamline energy use in all aspects of society, from home appliances to commercial consumption. While we need to reduce emissions on a global basis, it may in some instances be cheaper to reduce emissions in developing countries where it has been proven that most of the emissions come from. According to Bob Watson, chairman of the Intergovernmental Panel on Climate Change "The globe doesn't care where emissions come from”. (6) Therefore, the challenge is to get clean, cost-effective energy to developing countries in both rural and urban areas so that less green house gases are produced.
References
1. United States Environmental protection Agency. Greenhouse effect and gases- an EPA factsheet. Available in www-form>URL:
http://www.envirotools.org/factsheets/contaminants/greenhouse.shtml#top last viewed on 2nd February 2005
2. Greenhouse gases and global warming. Potential values excerpt from the inventory of u.s. greenhouse emissions and sinks: 1990-2000 Available in www-form>URL:
http://yosemite.epa.gov/oar/globalwarming.nsf/UniqueKeyLookup/SHSU5BUM9T/$File/ghg_gwp.pdf last viewed on 2nd February 2005
3. United States Department of Energy. Energy Efficiency and Renewable Energy. Biomass and the environment. Available in www-form>URL:
http://www.eere.energy.gov/biomass/for_policymakers.html last viewed on 2nd February 2005
4. Beinjin Times. Heat Wave in France Kills More Than 11,400. Saturday, August 30, 2003. Available in www-form>URL:
http://english.people.com.cn/200308/30/eng20030830_123396.shtml last viewed on 2nd February 2005
5. Knutson T.R, Tuleya R.E. Impact of CO2 – induced warming on simulated hurricane intensity and precipitation: sensitivity to choice of climatic model and convective parameterization. Journal of Climate 17:18 Sept 2004. Available in www-form>
http://www.gfdl.noaa.gov/reference/bibliography/2004/tk0401.pdf last viewed on 2nd February 2005
6. World Bank Group. Climate Change and Negotiations at the Hague. December 2000. Available in www-form>URL:
http://www.worldbank.org/wbi/B-SPAN/sub_climate2_ext.htm last viewed on 2nd February 2005
