A survey

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3.1 INTRODUCTION
A Survey of Environmental Concerns
The activities of industrial ecology are driven by the desire to avoid actual or perceived environmental impacts. Not all possible concerns can he addressed, of course, and some are more important than others. Thus, it is valuable for the industrial ecologist to have some understanding of the major environmental issues, lest action bedirected toward goals of little significance, Accordingly, we present in this chapter brief summaries of what we and others consider to be the most important of the environmental concerns. We will note later in the book an important fact: that most sources of emission to the environment have multiples effects, and most effects have multiples causes. As consequence, a single industrial product of processgenet y has the potential for impacts, even if often very small ones, on several environmental problems at once. Here, how-ever, we will consider the effects themselves rather than to discuss the important but complicating subject of sources.

An important distinguishing characteristic among environmental problems is their temporal scale. If the problems, once begun, will endure a long time,they should command more attention than those capable of being reversed quickly once their cause is removed. By the same token, problems of large spatial scale are of more general concern than those whose effects are restricted to smaller spatial regions, although the latter may be quite important to those proximate to them. The characteristics of a long time scale and a large spatial scale tend tooccur together, because long-lived contaminants more likely to over wide spatial areas during their lifetimes. Scale issues are compounded by sometimes lengthy lag times between forcing activities (e.g., increased emissions of CO2) and the resulting change in natural systems (e.g., global climate change). We present our discussions ordered by spatial scale of impact; to a first approximation, thisis also an order of importance.
One chapter in a book does not constitute a course in environmental science, of course, but will be a useful perspective later when we discuss decision making by product and process designers. Further information on environmental topics is available the chapter references.

3.2 GLOBAL SCALE CONCERNS
3.2.1 Global Climate Change
Climate is most succinctlydefined as the patterns of common meteorological conditions (temperature, precipitation, winds, etc.) over long time periods. (Thirty-year averages are often used as a modern measure of climate.) Climate has changed considerably over centuries or millennia throughout Earth's history, but concerns are now arising that climate changes may be proceeding extremely rapidly under the influence ofhumanity's activities. An example of the evidence leading to these concerns is the temperature record for the past century, as shown in Fig. 3.1.. These data show that about 0.5°C of warming has occurred in 100 years, and that the decade of the logos was the warmest during that period. The pattern roughly parallels that of the use or fossil fuels and the resulting injection into the atmosphere of gasesthat can absorb radiation and produce warming.

Several research groups have used computer models to examine the effects of increases in the concentrations of relatively active trace gases. Their calculations predict global temperature increases of 2-5°C by the year 2050. An average global temperature change of a few degrees does not seem very large until the change is put into perspective withpast climate oscillations. For example, the Little Ice Age of
Change relative to 1951-80 mean
1870 1890 1910 1930 1950 1970 1990 2010 Year
Figure 3.1 Annual deviation or the global mean (land and sea) temperature change aver the past century relative to the average for 1951-1980. The curve shows the results of a smoothing. ii her applier1 to the :throat values. (Policymakers Summary,...
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