Carbon IS A widely distributed element on the Earth. Pure carbon in one form is graphite. It can also take the form of diamonds after undergoing tremendous pressures and heat in volcanic pipes. Carbon is the basic atom in organic chemistry. Because carbon has four electrons, which can be joined to other atoms, it is able to form an enormous number of compounds. Some are simple and some are complex. The ones that matter the most to the issue of global warming are those that become involved in the chemistry of climate change.
The most common carbon compound that is involved in global warming is carbon dioxide (CO2). It is a very common emission from a wide variety of sources. Humans and animals, including birds, all exhale CO2 when they breathe. On the other hand, plants use CO2 as an essential part of the process of photosynthesis. Plants lock up tremendous amounts of carbon in trees, shrubs, grasses, and other plant materials. When these are buried, they can, under the right conditions of heat and pressure, become natural gas, oil, coal, peat, or other carbon remains.
Most carbon emissions come from natural sources. Volcanoes give off CO2, as do decaying plants. The Earth naturally has had an abundance of CO2 in its atmosphere. Without it, the Earth would become a block of ice. CO2 is the main compound involved in the greenhouse gas effect. This is the effect of sunlight striking the Earth, where it is either reflected immediately from bright surfaces such as the polar ice caps, or it is radiated in infrared wavelengths back into the atmosphere. CO2 and other carbon compounds such as methane, absorb and reflect back to Earth certain infrared wavelengths. Without this effect, all of the energy would return to outer space and the Earth would be much cooler.
The problem with carbon emissions in the current era is their volume. The rise of China and India as global producers and markets has followed on the huge volume of CO2 and other compounds that industrialized North America and Europe have spewed into the atmosphere for decades. It is anthropogenic (human-made) increases in the global atmospheric levels of carbon compounds that are blamed for the rises in temperatures globally in recent decades. Burning fossil fuels is probably the greatest source of carbon emissions. The use of oil and its derivatives is a major contributor. Oil is used to make fuel for airplanes, and in automobiles and trucks as gasoline or diesel fuel. In addition, coal has been burned for fuel for centuries. Today, coal-fired power plants burn whole trainloads of coal almost daily. The emissions, unless controlled, add huge quantities of smoke, much of which is CO2, to the atmosphere, where it increases the temperature of the planet through the greenhouse gas effect.
In addition to the burning of gasoline and coal, natural gas is a major, and still growing, fuel. To this is added the flaring of natural gas at refineries and at oil wells that have an excess of natural gas. It is mostly methane, but when burned, it becomes CO2 and water vapor. The consumption of huge quantities of natural gas produces CO2 in large quantities. Other liquefied petroleum gas products used for fuel are propane and butane. These also produce CO2 when burned.
Carbon emission sources also include livestock, rice paddies, deforestation, and the warming of the arctic tundra where decaying vegetation that has been thawed turns into a natural form of carbon emission. Researchers have concluded that livestock account for 18 percent of current levels of carbon emissions. The emission of cattle and many other farm animals produce gas in the form of methane. However, methane reacts with oxygen in the atmosphere to form CO2. Modern septic tanks that vent gases produced in their biodegradation of waste material emit methane, which is a gas that adds to the greenhouse gas stocks. Agricultural chemical fertilizers, as well as decaying vegetation, add vast amounts of carbon emissions on the Earth's surface and in the atmosphere. Cement production is another human source of carbon emissions.
The goal is to control global warming by controlling pollution from carbon gases produced by entities such as power plants. One idea is to develop a market in carbon-offset vouchers. Such programs seek to offer an economic incentive for a cleaner environment and a reduction in global greenhouse gases. Carbon emissions can be managed through a combination of government controls and market forces.
SEE ALSO: Automobiles; Carbon Cycle; Carbon Dioxide; Carbon Footprint; Carbon Permits; Carbon Sequestration; Carbon Sinks; Emissions, Trading; Methane Cycle.
BIBLIOGRApHY. M.M. Halmann and Meyer Steinberg, Greenhouse Gas Carbon Dioxide Mitigation: Science and Technology (CRC Press, 1998); Tingso Jianng, Economic Instruments of Pollution Control in an Imperfect World: Theory and Implications for Carbon Dioxide Emissions Control in China (Edward Elgar Publishing, 2004); Zach Willey and W.L. Chameides, eds., Harnessing Farms and Forests in the Low-Carbon Economy: How to Create, Measure, and Verify Greenhouse Gas Offsets (Duke University Press, 2007); Farhana Yamin, ed., Climate Change and Carbon Markets: A Handbook of Emissions Reduction Mechanisms (Earthscan, 2005).
Andrew J. Waskey Dalton State College
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