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ENVIRONMtNTAl. CHALLhNCtS i^ 



PEOPLE AND GLOBAL ENVIRONMENTAL CHANGE 



Although each of these problems has unique characteristics, all have a common 

 cause — the actions of humans. The earth's environment has experienced 

 dramatic changes in its five-billion-year history, but most have resulted from 

 natural events: the movement of continents and oceans, the coming and 

 going of ice ages, changes in the magnetic orientation of the earth, the evo- 

 lution and extinction of plant and animal species. These natural forces con- 

 tinue to v^ork today, but as a recent National Research Council study stressed: 

 "The earth has entered a period of hydrological, climatological, and biolog- 

 ical change that differs from previous episodes of global change in the extent 

 to which it is human in origin. Humans have always sought to transform 

 their surroundings. But, for the fint time, they have begun to play a central 

 role in altering global biogecKhemical systems and the earth as a whole."" 



POPULATION GROWTH AND INCREASING CONSUMER DEMAND 



Human population growth and increased and more diverse consumer de- 

 mand arc the chief driving forces for this stress on i..; biosphere. Population 

 growth has been dramatic. Human population did not reach the one billion 

 mark until about 18 jo. It reached two billion in the 1950s, four billion in 

 1975, and will probably reach six billion in 1997. Tiic rate of future growth 

 and the times Jt which population may be expected to stabilize \'ary greatly 

 from region to region and are determined by social and economic factors 

 that affect development in each country. With current growth rates, world 

 population would double again in 40 years, but the doubling figure may come 

 much sooner or later, depending upon policies adopted in the meantime." 



More people consume more resources. Although technological ad- 

 vance can help alleviate the stresses imposed by population growth, tech- 

 nical fixes and economic expansion alone cannot be relied on to solve the 

 population problem." 



But population giavrh perse is only pan of the problem. The quan- 

 tity and diversity of goods consumed by many of the eanh's people have 

 been rising. While this means that some people are better off, many of the 

 processes that raise living standards deplete the vital resources — soils, forests, 

 species, water — on which future populations depend. Thus, while popula- 

 tion growth is slowing in wealthier countries, these nations continue to use 

 more energy and other natural resources and produce more contaminants 

 than do developing nations. 



