Hotter or Colder ?
It was once thought that air pollution affected onlythe area immediately around large cities with factoriesand/or heavy automobile traffic.
Today, we know that although these are the areaswith the worst air pollution, the problem is literallyworldwide.
On several occasions over the past decade, a heavycloud of air pollution has covered the entire easternhalf of the United States and led to health warningseven in rural areas away from any major concentration of manufacturing and automobiletraffic.
In fact, the climate of the entire earth may be affected by air pollution.
Some scientists feel that the increasing concentration of carbon dioxide in the air resultingfrom the burning of fossil fuels (coal and oil) is creating a “greenhouse effect” — holding inheat reflected from the earth and raising the world's average temperature.
If this view is correct and the world's temperature is raised only a few degrees, much of thepolar ice cap will melt and cities such as New York, Boston, Miami, and New Orleans will be underwater.
Another view, less widely held, is that increasing particulate matter in the atmosphere isblocking sunlight and lowering the earth's temperature — a result that would be equallydisastrous.
A drop of just a few degrees could create something close to new ice age and would makeagriculture difficult or impossible in many of our top farming areas.
At present we do not know for sure that either of these conditions will happen (though onerecent government report prepared by experts in the field concluded that the greenhouseeffect is very likely).
Perhaps, if we are very lucky, the two tendencies will offset each other and the world'stemperature will stay about the same as it is now.
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