The Convention’s provisions concern all greenhouse gases not covered by the 1987 Montreal Protocol to the United Nations Convention on Protection of the Ozone Layer. The focus of the Kyoto Protocol, however, is on the following six:
i. Carbon dioxide (CO2);
ii. Methane (CH4);
iii. Nitrous oxide (N2O);
UN Framework Convention on Climate Change iv. Hydrofluorocarbons (HFCs);
v. Perfluorocarbons (PFCs); and vi. Sulphur hexafluoride (SF6).
The first three are estimated to account for 50, 18 and 6 percent, respectively, of the overall global warming effect arising from human activities. Although, these gases are naturally occurring, their emissions have increased dramatically over the past two centuries due to human activities. CO2 is produced in large quantities from the consumption of energy from burning fossil fuels, and deforestation. CH4 and N20 emissions are produced mainly from agricultural activities. The HFCs and PFCs are used as replacements for ozone-depleting substances such as chlorofluorocarbons (CFCs) currently being phased out under the Montreal Protocol. SF6 is used in some industrial processes and in electric equipment.
The relative level and impact of the six greenhouse gases is compared using their respective global warming potentials (GWP). A GWP is a measure, defined by the IPCC, of the relative effect of a substance in warming the atmosphere over a given period (100 years in the case of the Kyoto Protocol) - compared with a value of one for carbon dioxide. The IPCC Fourth Assessment report lists methane’s GWP as 25.
CARBON DIOXIDE
Carbon Dioxide (CO2) is a colorless, odorless non-flammable gas and is the most prominent Greenhouse gas in Earth's atmosphere. It is recycled through the atmosphere by the process photosynthesis, which makes human life possible. Photosynthesis is the process of green plants and other organisms transforming light energy into chemical energy. Light Energy is trapped and used to convert carbon dioxide, water, and other minerals into oxygen and energy rich organic compounds. Carbon Dioxide is emitted into the air as humans exhale, burn fossil fuels for energy, and de-forest the planet. Every year humans add over 30 billion tons of carbon dioxide in the atmosphere by these processes, and it is up thirty percent since 1750.
Ice core samples have also shown a dramatic increase in carbon dioxide levels. Drilling deep into glaciers and polar ice caps and taking out samples of ice, then melting the ice and capturing the gas has shown an increase in carbon dioxide concentrations over the past 100 years. Ice core samples are essentially "drilling through time", because the deeper the ice is, the older the ice is.
In 1996, carbon dioxide world emissions increased by 2.8 percent. The U.S. reported a 3.3 percent increase in CO2 concentrations. The U.S. continues to emit more than any other country in the world, accounting for 25 percent of all emissions. The European Union had an
UN Framework Convention on Climate Change increase of 2.2 percent, much larger than a small increase of 1.1 percent in 1995. Eastern Europe had a decreasing rate of -2.4 percent. China's increase in 1996 was 4.7 percent.
Fossil Fuels were created chiefly by the decay of plants from millions of years ago. We use coal, oil and natural gas to generate electricity, heat our homes, power our factories and run our cars. These fossil fuels contain carbon, and when they are burned, they combine with oxygen, forming carbon dioxide. The two atoms of oxygen add to the total weight. The World Energy Council reported that global carbon dioxide emissions from burning fossil fuels rose 12 percent between 1990 and 1995. The increase from developing countries was three times that from developed countries. Middle East carbon dioxide emissions from burning of fossil fuels increased 35 percent, Africa increased 12 percent, and Eastern Europe increased rates by 75 percent from 1990-1995.
Figure 2. Increase of carbon dioxide in the air over the past few centuries
Deforestation is another main producer of carbon dioxide. The causes of deforestation are logging for lumber, pulpwood, and fuel wood. Also contributing to deforestation are clearing new land for farming and pastures used for animals such as cows. Forests and wooded areas are natural carbon sinks. This means that as trees absorb carbon dioxide, and release oxygen, carbon is being put into trees. This process occurs naturally by photosynthesis, which occurs less and less as we cut and burn down trees. As the abundance of trees declines, less carbon dioxide can be recycled. As we burn them down, carbon is released into the air and the carbon bonds with oxygen to form carbon dioxide, adding to the greenhouse effect.
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Figure 3. Global Carbon Cycle (Billion Metric Tons Carbon)
METHANE
Methane is a colorless, odorless, flammable gas. It is formed when plants decay and where there is very little air. It is often called swamp gas because it is abundant around water and swamps. Bacteria that breakdown organic matter in wetlands and bacteria that are found in cows, sheep, goats, buffalo, termites, and camels produce methane naturally. Since 1750, methane has doubled, and could double again by 2050. Each year we add 350-500 million tons of methane to the air by raising livestock, coal mining, drilling for oil and natural gas, rice cultivation, and garbage sitting in landfills. It stays in the atmosphere for only 10 years, but traps 20 times more heat than carbon dioxide.
Figure 4. Methane is on the rise since 1750
UN Framework Convention on Climate Change Rice cultivation has developed into a large business; farmland has doubled in the past 45 years. It feeds one-third of the World's population. It grows mostly in flooded fields, where bacteria in water-logged soil release methane.
Livestock such as cows, sheep, goats, camels, buffaloes, and termites release methane as well. Bacteria in the gut of the animal break down food and convert some of it to methane.
When these animals belch, methane is released. In one day, a cow can emit ½ pound of methane into the air. Imagine 1.3 billion cattle each burping methane several times per minute!
NITROUS OXIDE
Nitrous oxide is another colorless greenhouse gas, however, it has a sweet odor. It is primarily used as an anesthetic because it deadens pain and for this characteristic is called
“laughing gas”. This gas is released naturally from oceans and by bacteria in soils. Levels of nitrous oxide gas have risen by more than 15 percent since 1750. Each year we add 7-13 million tons into the atmosphere by using nitrogen based fertilizers, disposing of human and animal waste in sewage treatment plants, automobile exhaust, and other sources not yet identified. It is important to reduce emissions because the nitrous oxide we release today will still be trapped in the atmosphere 100 years from now.
Figure 5. Nitrous Oxide has been on the rise since 1750
Nitrogen based fertilizer use has doubled in the past 15 years. These fertilizers provide nutrients for crops; however, when they breakdown in the soil, nitrous oxide is released into the atmosphere. In automobiles, nitrous oxide is released at a much lower rate than carbon dioxide, because there is more carbon in gasoline than nitrogen
UN Framework Convention on Climate Change FLUOROCARBONS
Fluorocarbon is a general term for any group of synthetic organic compounds that contain fluorine and carbon. Many of these compounds, such as chlorofluorocarbons (CFCs), can be easily converted from gas to liquid or liquid to gas. Because of these properties, CFCs can be used in aerosol cans, refrigerators, and air conditioners. Studies in the 1970s showed that when CFCs are emitted into the atmosphere, they break down molecules in the Earth's ozone layer. Since then, the use of CFCs has significantly decreased and they are banned from production in the many countries. The substitutes for CFCs are hydrofluorocarbons (HFC's). HFCs do not harm or breakdown the ozone molecule, but they do trap heat in the atmosphere, making it a greenhouse gas, aiding in global warming. HFCs are used in air conditioners and refrigerators.
Table 1. Types of greenhouse gases & their sources
Greenhouse Gas Chemical Symbol Sources Controlled
Carbon Dioxide CO2 Occurs naturally. Other sources are landfills, coal mines, paddy fields, natural gas systems, and livestock.
Nitrous Oxide N2O Generated by burning fossil fuels, in the manufacture of fertilizer and by cultivation of soils.
Perfluorocarbons (PFCs)
Various compounds Human-made chemicals. A by-product of aluminum smelting. Also used as a replacement for CFCs in manufacturing semiconductors.
HFC’s Various compounds Human-made chemical. Used largely in refrigeration and insulating foam.
Sulphur Hexafluoride
SF6 Used largely in heavy industry to insulate high voltage equipment and to assist in the manufacture of cable cooling systems.
Uncontrolled
Water Vapour H2O (gas) Naturally occurring. Rising global temperatures may act to increase water vapour in the atmosphere.
Ozone O3 Naturally occurring. Also created by reactions involving
nitrogen oxide gases resulting from motor vehicles and power plants. Ozone at ground level and in the lower atmosphere is linked with smog and health problems.
However, in the upper atmosphere, it helps to protect the earth from ultra-violet radiation and chemicals which tend to destroy ozone in the upper atmosphere are regulated under the Montreal Protocol.
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THE GREENHOUSE EFFECT
The earth’s climate is driven by a continuous flow of energy from the sun. This energy arrives mainly in the form of visible light. About 30 percent is immediately scattered back into space, but most of the remaining 70 percent passes down through the atmosphere to warm the earth’s surface.
The earth must send this energy back out into space in the form of infrared radiation. Being much cooler than the sun, the earth does not emit energy as visible light. Instead, it emits infrared, or thermal radiation. This is the heat thrown off by an electric fire or grill before the bars begin to glow red.
Figure 6. Process of global warming and how greenhouse gases create the "greenhouse effect"
Greenhouse gases in the atmosphere block infrared radiation from escaping directly from the surface to space. Infrared radiation cannot pass straight through the air like visible light.
Instead, most departing energy is carried away from the surface by air currents, eventually escaping to space from altitudes above the thickest layers of the greenhouse gas blanket.
The main greenhouse gases are water vapor, carbon dioxide, ozone, methane, nitrous oxide, and halocarbons and other industrial gases. Apart from the industrial gases, all of these gases occur naturally. Together, they make up to less than 1 percent of the atmosphere. This is enough to produce a “natural greenhouse effect” that keeps the planet some 30oC warmer than it would otherwise be - essential for life as we know it.
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Levels of all key greenhouse gases (with the possible exception of water vapor) are rising as a direct result of human activity. Emissions of carbon dioxide (mainly from burning coal, oil, and natural gas), methane and nitrous oxide (due mainly to agriculture and changes in land use), ozone (generated by automobile exhaust fumes and other sources) and long-lived industrial gases such as CFCs, HFCs, and PFCs are changing how the atmosphere absorbs energy. Water vapor levels may also be rising because of a “positive feedback”. This is all happening at an unprecedented speed. The result is known as the “enhanced greenhouse effect”.
The climate system must adjust to rising greenhouse gas levels to keep the global “energy budget” in balance. In the long term, the earth must get rid of energy at the same rate at which it receives energy from the sun. Since a thicker blanket of greenhouse gases helps to reduce energy loss to space, the climate must change somehow to restore the balance between incoming and outgoing energy.
This adjustment will include a “global warming” of the earth’s surface and lower atmosphere. Warming up is the simplest way for the climate to get rid of the extra energy.
But even a small rise in temperature will be accompanied by many other changes: in cloud cover and wind patterns, for example. Some of these changes may act to enhance the warming (positive feedbacks), others to counteract it (negative feedbacks).
Meanwhile, man-made aerosols have an overall cooling effect. Sulphur emissions from coal and oil-fired power stations and the burning of organic material produce microscopic particles that can reflect sunlight back out into space and also affect clouds. The resultant cooling partly counteracts greenhouse warming. These aerosols, however, remain in the atmosphere for a relatively short time compared to the long-lived greenhouse gases, so their cooling effect is localized. They also cause acid rain and poor air quality, problems that need to be addressed. This means we should not rely indefinitely on the cooling effect of aerosols.
Climate models estimate that the global average temperature will rise by about 1.4 - 5.8oC (2.5 - 10.4°F) by the year 2100. This projection uses 1990 as a baseline and assumes that no policies are adopted for minimizing climate change. It also takes into account climate feedbacks and the effects of aerosols as they are presently understood.
Past emissions have already committed us to some climate change. The climate does not respond immediately to emissions. It will therefore continue to change for hundreds of years even if greenhouse gas emissions are reduced and atmospheric levels stop rising. Some important impacts of climate change, such as a predicted rise in sea level, will take even longer to be fully realized.
There is new and stronger evidence that climate change has already begun. The climate varies naturally, making it difficult to identify the effects of rising greenhouse gases.
However, an increasing body of observation now presents a collective picture of a warming world. For example, the pattern of temperature trends over the past few decades resembles the pattern of greenhouse warming predicted by models; these trends are unlikely to be due
UN Framework Convention on Climate Change entirely known sources of natural variability. Many uncertainties remain, however, such as how changes in cloud cover will influence future climate.