Fossil fuels atmospheric carbon dioxide from

Over the same period, humans released at least 175 billion tons of atmospheric carbon dioxide from fossil-fuel emissions alone. 

We depend on burning fossil fuels (coal, natural gas, or petroleum) for energy. We burn coal and natural gas to produce electricity, we burn gasoline in the internal combustion engine, and we burn natural gas, oil, wood, and coal to heat homes. In addition, industrial processes burn fuel to produce heat. As a result of all this burning of fossil fuels, the carbon dioxide level in the atmosphere has risen from 318 parts-per-million (ppm) in 1960 to 362 parts-per-million (ppm) in 1998. (For a discussion of the concentration unit ppm, see Chapter 11.) The excess carbon dioxide has led to an increase of about a half-degree in the average temperature of the atmosphere. 

AssiDoman carbort dioxide emissions derive from biofuels and fossit fuels. The carbon dioxide from biofuels, COj biogenic, which constitutes tN greater part, is bound in the growing forest and therefore does not influence Uie concentration of CO in the atmosphere. The carbon dioxide that is emitted by combustion of fossil fuels in forestry, pulp arid paper mik, and transport does, however, contribute to the greenhouse effect... 

Rayon is unique among the mass produced man-made fibers because it is the only one to use a natural polymer (cellulose) directly. Polyesters, nylons, polyolefins, and acryflcs all come indirectly from vegetation they come from the polymerization of monomers obtained from reserves of fossil fuels, which in turn were formed by the incomplete biodegradation of vegetation that grew millions of years ago. The extraction of these nonrenewable reserves and the resulting return to the atmosphere of the carbon dioxide from which they were made is one of the most important environmental issues of current times. CeUulosic fibers therefore have much to recommend them provided that the processes used to make them have minimal environmental impact. 

Fig. 11 -25 Release of carbon from the biota and soils globally according to various estimates. The fossil fuel flux is from data of Rotty. (Modified with permission from G. M. Woodwell et al. (1983). Global deforestation Contribution to atmospheric carbon dioxide. Science 222,1081-1086, AAAS.)...

There is a consensus amongst scientists that biofuels used in a sustainable manner result in no net increase in atmospheric carbon dioxide (CO ). Some would even go as far as to declare that sustainable use of biomass will result in a net decrease in atmospheric CO (Jefferson et al., 1991). This is based on the assumption that all the COj given off by the use of biomass fuels was recently taken in from the atmosphere by photosynthesis. Increased substitution of fossil fuels with biomass-based fuels would therefore help reduce the potential for global warming, caused by increased atmospheric concentrations of COj. 

Industrial burning of fossil fuels in power plants and factories is the largest source of human-created atmospheric carbon. Emissions from automobiles—from simply driving cars—are another major, but much smaller, source. The burning of rain forests in areas around the equator is another major source of carbon dioxide in the atmosphere. (This burning is mostly done to clear land for agriculture.) Altogether, these carbon sources are cause for present and future concerns. 

Careful measurements show that concentrations of atmospheric carbon dioxide have been rising in the last 150 years, largely because of the increased use of fossil fuels, from an estimated 290 parts per million (ppm) in 1850 to a current level of 370 ppm (Figure 9.17). Thus, there is concern among many atmospheric... 

Bacastrow R.B. and Keeling C.D. (1979) Models to predict future atmospheric CO2 concentrations. In Workshop on the Global Effects of Carbon Dioxide from Fossil Fuels U.S. Dept. Energy Conf. -770385, NTIS, Springfield, VA, 72-90. 

Many greenhouse gases such as water vapor occur naturally and are important for life to exist on Earth. Human production of carbon dioxide from combustion of fossil fuels has increased the concentration of this important greenhouse gas to its highest value since millions of years ago. The precise impact of these changes in the atmosphere is difficult to predict and is a topic of international concern and political debate. 

There are additional problems with fossil fuels. The waste products from burning fossil fuels significantly affect our environment. For example, when a carbon-based fuel is burned, the carbon reacts with oxygen to form carbon dioxide, which is released into the atmosphere. Although much of this carbon dioxide is consumed in various natural processes such as photosynthesis and... 

Between 1850 and 1998 atmospheric carbon dioxide levels have risen from 285 to 366 ppm, mainly because of the combustion of fossil fuels and changes in land use from forestry to agriculture. This unbalanced release of stored carbon is now generally accepted as setting us on a global climate change journey with an unknown but likely to be unpleasant destination. Combustion of fossil fuels alone contributed 6.3 Gt (gigatonnes or 10 tonnes) of carbon dioxide emissions annually between 1989 and 1998. 

There are subtle reasons why venting carbon dioxide from trash incineration is of far less concern than the venting of the same gas from fossil fuel combustion reactions. Large portions of the carbon compounds in domestic trash are paper and food wastes. Only a few years ago the carbon contained in these plant products was part of the atmosphere. On a long-term basis, returning this carbon to the atmosphere has no effect on the overall carbon dioxide balance it simply speeds up the rate of recycle of carbon from plant material to the biosphere. 

The structural molecules of the skeletons and shells of invertebrates, which function as physical defenses against predation, are important in marine environments, where they produce carbonate and silicate rocks. Deposition in anaerobic environments has also been the basis for the formation of the extensive deposits of gas and oil that now fuel modern industrial societies. Removal of carbon from the biosphere by organisms to produce carbonate rocks, coal, oil, and hydrocarbon gases has been responsible for the presence of oxygen in the atmosphere of the Earth. Reversal of this process by human consumption of fossil fuels has already produced a detectable increase in atmospheric carbon dioxide. 

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