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1974, scientists identified a chain reaction that begins with CFCs and sunlight and ends with the production of chlorine atoms. A single chlorine atom can destroy as many as 100,000 ozone molecules. The consequences could be long-lasting and severe, including increased cancer rates and global warming.30

In 1987, the Montreal Protocol began a global phase-out of CFC production. That in turn provided the market force that fueled the development of new, non-CFC refrigerants. Although the results of CFC use provide an example of the unintended negative consequences of technology, the response demonstrates the influence of science in diagnosing problems and providing effective solutions.

Agricultural Mechanization

Advances in agriculture have vastly increased farm productivity and food production. The food supply for the world’s population of more than 6 billion people comes from a land area that is 80% of what was used to feed 2.5 billion people in 1950. However, injudicious application of mechanization also led to increased soil erosion. Since 1950, 20% of the world’s topsoil has been lost—much of it in developing countries. Urban sprawl, desertification, and over-fertilization have reduced the amount of arable land by 20%.31 Such improvements as conservation tillage, which includes the use of sweep plows to undercut wheat stalks but leave roots in place, have greatly reduced soil erosion caused by traditional plowing and have promoted the conservation of soil moisture and nutrients. Advances in agricultural biotechnology have further reduced soil erosion and water contamination because they have reduced the need for tilling and for use of pesticides.


Improvements attributable to declining mortality and better environmental monitoring are compounded by gains made possible by other advances in technology. The result has been a general enhancement in the quality of life in the United States as viewed by most observers.


National Academy of Sciences. Ozone Depletion, Beyond Discovery Series. Washington, DC: National Academy Press, April 1996.


P. Raven. “Biodiversity and Our Common Future.” Bulletin of the American Academy of Arts & Sciences 58(2005):20-24.

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