What the future holds.

Some people argue that global warming will bring doom," says Jerry Mahlman, lab rector at the U.S. National Oceanic and Atmospheric Administration (NOAA) in Princeton, New Jersey. "Others tell you nothing will happen"

Most scientists are quick to stress that any effects of global warming could vary drastically from one area to another, even in the same region. But here's what many computer models project for the future (see maps): If [CO.sub.2] levels double in the atmosphere from pre-industrial levels 200 years ago, then annual average temperatures are projected to climb by 1.1 [degrees] to 2.8 [degrees] C (2 [degrees] to 5 [degrees] F) in most of the world, and by about 3.9 [degrees] to 5.6 [degrees] C (7 [degrees] to 10 [degrees] F) in northern regions, which include much of the U.S. If [CO.sub.2] levels were to quadruple, then annual average global temperatures could climb by 5.6 [degrees] to 13.9 [degrees] C (10 [degrees] to 25 [degrees] F)!

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What does that mean for the global climate? Substantial warming would produce: more rain on average around the world, but again varying locally; record heat waves; and severe drying of soil moisture in areas such as the American Midwest.

How does this affect you? If you live on a farm in Pennsylvania, for example, you might see warmer winters and longer growing seasons, In Nebraska, global warming might spell dryer, hotter summers with more potential for droughts.

Sea levels are also projected to rise by 15 to 90 cm (6 to 35 in.) during the next century. While many glaciers have begun to thaw, polar ice masses remain stable for now. Oceans will rise primarily because heated molecules expand water volume. Residents near the coastline, such as in Florida, might see beaches recede and actually end up underwater (red areas in map).

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Of course dicey factors will impact global warming. Industrial pollutants such as sulfur compounds tend to make clouds more reflective, letting less sunlight through. This might cool surface temperatures in some areas. Trees, plants, and crops also absorb enormous amounts of [CO.sub.2] for food and growth. That could also reduce global warming.

While future effects of global warming remain a mystery, most scientists agree it will take the world working together as global community to keep global warming under control.