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Table of Contents

Cover Story

Grades 2-3

The Earth Heats Up

Large sheets of ice at the North and South Poles are melting. Ocean and air temperatures are changing unexpectedly. Scientists say these changes show that the world is getting warmer by a process called global warming.

A warmer world may not sound so bad. But it could mean trouble for plants, animals and people. The melting of large ice sheets, called glaciers, could cause flooding. Polar bears could die off if their icy habitat keeps melting. "An ecological time bomb is ticking," says scientist Stephen Byers.

A Changed Planet
During the 1900s, the earth's temperature rose about 1°F. Scientists blame pollution. Recent studies suggest that the world's temperature is heating up faster than we thought.

As more countries build factories and use cars, more pollution is released into the air. Part of that pollution is a gas called carbon dioxide (die-ahk-side). When this gas gets into the atmosphere, it acts like the walls and ceiling of a greenhouse. A greenhouse is a glass building where plants are grown. The glass lets in sunlight. It keeps in much more heat than it releases.

Now, some nations are taking steps to slow global warming. Starting February 16, at least 140 nations will begin following the Kyoto (kyoh-toe) Protocol. The United States is not obeying the treaty. The treaty sets targets for nations to cut pollution by 2012.

Scientists are working on new, cleaner ways to power cars and factories. Cutting pollution won't be easy or cheap. But the cost of doing nothing is too high.

Next: Message to the Nation