Global Perils
The Earth will heat up by between 1.8 and 6.3 degrees Fahrenheit over the next century, according to an international panel of scientists. But exactly how global warming will affect people and wildlife in any given area is still highly uncertain. Here are some of the latest projections by the United Nations' Intergovernmental Panel on Climate Change.
The Weather
Warmer and wetter -- but not everywhere. Scientists say higher temperatures could intensify the global hydrological cycle, leading to heavier rainfall and more frequent flooding in some areas. Other regions could be plagued by chronic droughts as weather patterns change. Most of the planet could see an increase in the number of extremely hot summer days, although the greatest warming would occur in northern latitudes during winter.
Sea Level
Heat causes water to expand, a fact that could account for a significant rise in sea levels over the next century. And if glaciers and polar ice sheets continue to melt, the oceans could claim an even bigger share of coastal real estate. The increase could be as little as six inches or as much as three feet -- a jump that would swamp large chunks of coastal Florida and Louisiana and displace 70 million people in Bangladesh.
Wildlife
Some species confronted by rapidly changing climates may be forced to move to new habitats, but others would likely be lost. In North America, for example, warmer weather could dry up prairie "pothole" wetlands that support 50 percent of the continent's waterfowl.
Human Health
Winter cold could be less lethal, but heat-related deaths and illnesses could increase in the summer months. So could respiratory problems from urban air pollution. Public health officials are worried that warmer weather could allow the spread of infectious and insect-borne diseases into new areas. One study predicts as many as 80 million additional cases of malaria worldwide each year.
Agriculture
Despite greater rainfall totals in some areas, higher summer temperatures could result in a sharp drop in soil moisture. The losses could be most severe in continental interiors, such as America's Great Plains. But warming in the northern latitudes could also open new areas to agricultural production and make up for deficits elsewhere.
Forests
A third of the Earth's forests would likely undergo major changes, and in some regions entire types of forests may disappear. Tree species can adapt to gradual changes in climate over time by colonizing new areas, but if the temperatures rise rapidly some species may be unable to keep up.
© Copyright 1998 The Washington Post Company
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