Carbon dioxide anthropogenic emissions

The use of coal for electricity generation is responsible for about 32% of anthropogenic carbon dioxide emissions in the U S. 11 As shown by France, it is possible to displace virtually all the coal used in electricity generation. Thus, France in 1997 obtained about 78% of its electricity from nuclear power and only about 5% from coal. Further reductions in carbon dioxide emissions could be made by the electrification of other sectors of the energy economy, including buildings, and eventually perhaps much of transportation. 

All of this suggests the conclusion that Arctic waters remove carbon dioxide from the atmosphere. Therefore, once again a detailed study of this process is needed before a global model of carbon cycle can be specified, thereby improving the accuracy of estimation of the greenhouse effect due to emissions of anthropogenic... 

Trends in atmospheric concentrations and anthropogenic emissions of carbon dioxide. (From Oak Ridge National Laboratory, Carbon Dioxide Information Analysis Center, http //cdiac. 

In the last 150 years the anthropogenic emission of sulfur has increased dramatically, primarily due to combustion processes [1]. In the 1950s anthropogenic emission surpassed natural emission and the atmospheric sulfur cycle is one of the most perturbed biogeochemical cycles [1,2]. The oceans are the largest natural source of atmospheric sulfur emissions, where sulfur is emitted in a reduced form, predominantly as dimethyl sulfide (DMS) and to a much lesser extent carbonyl sulfide (OCS) and carbon disulfide (CS2) [3]. Ocean emitted DMS and CS2 are initially oxidised to OCS, which diffuses through the troposphere into the stratosphere where further oxidation to sulfur dioxide (SO2), sulfur trioxide (SO3) and finally sulfuric acid (H2SO4) occurs [1-4]. 

The extent to which man-made carbon dioxide emissions contribute to global warming is still an issue of considerable debate. Analysis indicates that while the contribution to the total amount of this gas in the atmosphere from anthropogenic sources amounts to 3 to 4 percent, the problem is that carbon dioxide remains in... 

The transportation sector accounts for 68 percent of all of the petroleum used and one-third of the anthropogenic carbon dioxide emissions in the United States. In addition, the utilization of internal combustion engines for transportation results in a significant amount of nitrogen oxides and particulate emissions. 

It should be mentioned that only about the half of anthropogenic C02 remained airborne in the past decades.4 However, this does not necessarily mean that the fraction of man-made C02 stored in the atmosphere will always be the same in the future. For this reason it is essential to determine from past variations the factors governing the fate of anthropogenic carbon dioxide. It is also essential to include these factors in so-called reservoir or box models5 to calculate, on the one hand, the fraction absorbed by oceans and, on the other hand, the part of the emission used by the land biota. Since the uptake of carbon dioxide by ocean waters is governed by more or less known physical and chemical laws the response of land plants to the increase of C02 level, which is much more complicated, can be estimated by difference between total C02 input and oceanic absorption (e.g. Keeling, 1973). 

Estimates of annual amounts of emissions released into the earth s atmosphere are remarkably different from each other, depending on the choice of balance models [5-24]. For the anthropogenic sources, the following substances may be listed in decreasing order of importance carbon dioxide, carbon monoxide, sulphur oxides, hydrocarbons, nitrogen oxides and liquid and solid particles. A summary of relative contributions of these substances to total emissions of main types of anthropogenic sources is given in Table 5.8. 

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