Carbon dioxide is the primary driver of global warming. It is freely available in the Earth's atmosphere, released by man and other animals, and used up by plants in the processes of respiration and photosynthesis. CO₂ is a product of the combustion of carbon related compounds such as fossil fuels and organic matter; it can be produced synthetically by acidification and decomposition of metallic carbonates, among other methods of chemical reaction. However, CO₂ is produced industrially through different processes of combustion of carbonaceous fuels, decomposition of calcium carbonates, fermentation, and from gas wells. It can also result from the oxygénation of the product of the incomplete combustion of automobile and generator fuels.

It has great industrial uses in the food, oil, and chemical industries. Of all the GHGs, it occupies the center stage of the world's basic discussion on global warming and climate change because of its effect on the environment. Human activities have contributed to a significant increase in atmospheric levels of CO₂. These concentrations have increased by 33 percent, from around 280 parts per million (ppm) as recently as the late 1700s, to 316 ppm in 1959, to 373 ppm in 2002. In the stratosphere, it is highly stable and could exist in the atmosphere for more than 100 years. This stability period means it cannot be eliminated from the Earth's atmosphere, but can only be indirectly reduced by reducing the activities producing it.

Carbon dioxide's importance in greenhouse effect is based on its ability to absorb much of the electromagnetic radiation below the visible light wavelength, trapping heat radiation that attempts to escape from the Earth, thereby causing an increase in the Earth's temperature. It is reported that doubling of CO₂ produces a temperature rise between 2.7-9 degrees F (1.5-5 degrees C), leading to a warming of between 0.9-3 degrees F (0.5-1.7 degrees C). Also, it has been established that CO₂ has significant effect in increasing the global surface temperature of the Earth's atmosphere, and of the GHGs (excluding water vapor), it is the most powerful, with a radiative forcing of 1.5 W/m.².

Carbon dioxide is not the only GHGs increasing in its stratospheric level. Methane is also increasing in concentration. Methane is considered as an important greenhouse gas. It is believed to be the second most powerful greenhouse gas (excluding water vapour), and its concentration in the stratosphere affects the Earth's heat balance, and thus temperature. Methane is a natural gas with a chemical compound consisting of one carbon and four hydrogen atoms bonded covalently together, the simplest alkane, relatively abundant and gaseous at normal temperature and pressure. The Earths crust contains huge amounts of the gas, produced anaerobically by biomethanation, and also released to the atmosphere by mud volcanoes. It is colorless and odorless, a major component of fossil fuel, about 97 percent by composition, having different uses ranging from industry, power generation, to manufacturing processes. Apart from it being a major component of natural gas, it is obtained from the anaerobic digestion of organic matter, manure, sewage, and solid and biodegradable wastes.

Major research findings have pointed to changes in climate temperature, including widespread melting of snow and ice and rising global mean sea level. Mountain glaciers, snow cover, and Arctic sea ice levels have also fallen.

In the Earth's atmosphere, it adds to global climate alteration. Although not as stable as CO₂, having a stability period of 10 years, it is however, 100 times stronger than CO in its greenhouse effect. A ton of methane is reported to have 25 times the temperature effect of the same size of CO₂ on the environment after every 100 years, and accounts for 20 percent of the total radiative forcing of all the combined GHGs. However, the cumulative effect of CO₂ is more than that of methane because of the enormous amount of it present in the atmosphere, with methane having a large effect on the environment over a short period of 10 years in comparison to the small effect of CO₂ over a longer period of over 100 years. The effects of methane include the absorption of infrared radiation, affecting the troposheric and stratospheric ozone (O₃).

Nitrous oxide is another GHGs whose atmospheric levels have continued to rise because of human activities. It is also referred to as dinitrogen monoxide and is a colorless, odorless, covalently bonded gas that can be produced synthetically and biologically. It is a by-product of feedlots, auto emissions, and modern agricultural practices, whose atmospheric levels have increased by 17 percent since the mid-16th century It is also emitted from processes ranging from wastewater treatment, gas combustion, industrial processes, fertilization, and microorganism's reactions in soil and in the ocean. It has a stability period of 150 years, and is about 200 times as potent a greenhouse gas as CO₂. Today, human-fuelled activities contribute 33 percent of nitrous oxide emissions into the atmosphere. Although the quantity of N₂O present in the atmosphere in comparison to CO₂ is very small, its effect as a greenhouse gas is much more potent; one molecule of N₂O has a heat absorbing ability equivalent to 200 molecules of CO₂. It is reported that while NO_x is partially responsible for increased ozone (O₃) production as part of photochemical smog production in urban areas near the Earths surface, it also plays a role in its destruction in the stratosphere, where the O₃ would have been helpful in absorbing excessive ultraviolet radiation. N₂O is converted to NO in the atmosphere, which on reaching the stratosphere reacts with O₃ to result in its depletion. It is however noted that the gas absorbs thermal radiation at the same wavelength as methane. The concentration of oxide in the atmosphere is presently increasing above the pre-industrial level at a rate of approximately 0.25 percent per year, due largely to anthropogenic biomass burning and bacterial oxidation of fertilizer nitrogen; it absorbs light in a broad continuum from and including 260 nm to 182 nm.

Water vapor is also considered a greenhouse gas. This is the gaseous form of liquid water, and is enormously abundant in the atmosphere, much more than other GHGs. There have been a lot of research arguments on the impact of water vapor on the atmosphere, but over the years, it has come to be known as the most important greenhouse gas. It strongly absorbs thermal radiation with wavelengths less than eight μm and greater than 18 μm.

Another group of greenhouse gases, the halocarbon gases (CFCs) are synthetic-anthropogenic molecules that contain chlorine, fluorine, and carbon atoms bonded together. They add greatly to the atmosphere's heat-absorbing ability by actively absorbing radiation in the atmospheric radiative window of seven to 12 μm. They are non-soluble, inert, and have long stability period, capable of being broken up by photolysis to release chlorine, which in turn damage the ozone layer. Of all the chlorofluoro carbons, the significant CFCs are CFC-11 (trichloroflu-oromethane) and CFC-12 (dichlorofluoromethane). The atmospheric residence time of CFC-12 is 102 years and its 100-year GWP relative to CO₂ is about 8,500, while CFC-11 has stability period of 50 years and a 20-years GWP of 5,000. Some countries like the United States and Sweden have taken steps to reduce the quantity of CFCs in the atmosphere in line with the Montreal protocol.

There are other gases that adversely affect the Earth's atmosphere, creating global warming concerns. Such gases include per-fluorocarbons (PFCs), sulphur hexafluoride (SF₆), and pollutants such as SO₂. SO₂ on the other hand, is a gas that emanates as a result of human activities from combustion of coal and the exhaust of cars. It acts to cool the atmosphere, contrary to other GHGs, however, its effects as a regulatory gas to the global warming effects of the GHGs is limited by its life span on the Earth's surface, which is not more than a week.

Human-induced warming over recent decades is already affecting many physical and biological processes on a global scale. Major research findings have pointed to changes in climate temperature, including increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level. Due to this changing climatic condition, much of the world's population is expected to face serious water shortages by the turn of the century, food production is expected to decline in low-altitude areas, and desertification will lead to food shortages. There are reported cases of increased intensity of tropical cyclones in the north Atlantic within the past 25-30 years, and storms with heavy precipitation have also increased. Mountain glaciers, snow cover, and Arctic sea ice have also fallen.

The report of the Intergovernmental Panel on Climate Change (IPCC) in April 2007 reveals that the rising temperature of the global environment may result in the altered spatial distribution of some infectious disease vectors, meaning that the rate of transmission of such disease like malaria in Africa and other parts of the world could increase. It is also reported that diseases such as those carried by insects, ticks, and other insect vectors are likely to be affected by environmental changes because these creatures are themselves very sensitive to vegetation, temperature changes, humidity, and rainfall.

There is the likelihood of continuous enhanced coastal erosion, increased farming seasons, increased plant growth, and increased flooding as currently observed in different parts of Asia, western Europe, and west Africa. There would also be more hot days and nights, and extreme variations in the amount of rainfall across the globe, where high altitude and generally wet places will tend to receive more rainfall, while tropical regions and generally dry places will probably receive less rain. This increase in rainfall will come in the form of more rainy days; in between these periods there will be longer periods of light or no rain, bringing about increasing frequency of drought. Hurricanes will also probably increase due to warmer ocean surface temperature.

Animal and plant species have begun dying off or changing sooner than predicted because of global warming. Global warming might spark the mass extinction of endangered species, eroding biodiversity. Several scientific reports have pointed to trends of animal populations moving northward as a result of alteration to their natural habitat; of species adapting slightly because of climate change; of plants blooming earlier; and of an increase in pests and parasites.

Global warming will potentially stifle life-giving microscopic plants that live in the surface layer of the marine ecosystems, thereby cutting marine food production and accelerating climate change. Phytoplank-ton are not only the foundation of the marine food chain, but every day they take more than 100 million tons of CO₂ out of the atmosphere. As global warming raises the surface layer of the ocean, it becomes lighter and, therefore, separated from the cooler depths from which the phytoplanktons get many of their nutrients. This reduces their assemblage, not only reducing the food in the oceans, but also reducing the amount of CO₂ they take from the air and, therefore, accelerating the climate warming process.

Apart from the direct effects of global warming on the global climate, there is the issue of the indirect effects of it on the sociological, political, and economic climate of nations. It is reported that the social, economic, and physical infrastructural indices of a geographical region has evolved from the adaptation of all that regions society to the prevailing climate and to the hydrological conditions brought about by that climate over a finite time period. In cases, therefore, when the frequency of occurrence and magnitudes of phenomenon such as typhoons, floods, and droughts have altered the habitability of that region and affected the social and economic activities of its dwellers, there is bound to be the development of unwanted and unexpected stresses.

Due to these direct effects on the global climate, nations worst hit by some or few of the elements of global warming effects are most likely to suffer from increasing under population, as gradually, people begin to move away from areas of incessant flooding, drought, and erosion, to areas of calmness and freedom from such environmentally dictated occurrence. This would invariably lead to the overpopulation of neighboring towns, cities, and countries, creating attending situations associated with such phenomenon. Issues of over population have over the years been linked to over-use of available natural and developed resources. As the average population of a place begins to grow, higher demand would begin to be placed on living factors such as energy, water, space, food, good health facilities, shelter, and security. The result is that more waste would be produced due to increased human presence and activities.

There would also be the challenge of higher demand placed on available water resources, and serious deforestation as a result of people felling trees and clearing grounds for shelter and other human related activities. Forest reserves would be taken over by people, and wildlife would be seriously endangered. This could lead to the problem of erosion and water pollution, as particles of erosion could be washed into fresh water resources, creating an additional need for governments to clean up the water and make it safe for domestic use. In effect, this would bring about a depletion of available resources, carrying with it some environmental issues of degradation and mismanagement.

The problem of the environment would be further aggravated, creating a recycling of environmental disturbances and furthering the effects of global warming. In Africa and some other developing countries, over population has resulted in serious famine and poverty; there have also been cases of close to zero health care, with people suffering from serious curable and incurable diseases. More so, as people migrate from areas hit by global warming impacts to other places, there could be a greater instance of disease transfer. Diseases such as polio and malaria, which the world has been trying to curb, could upsurge. Human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS) is another human vectored disease that could increase due to huge migration of people. There could also be greater territorial wars, international disputes, and disrespect for boundary policy if the impacts of global warming are not addressed globally. Thus, global warming does not only affect the climate of nations; it also affects the sociological, political, and economic standards of nations.

Carbon Dioxide, Climate Change, Effects, Greenhouse Effect, Greenhouse Gases, Policy, International