Our factories and homes burn coal and oil. Every year we have forest fires somewhere. Many scientists believe that the climate is changing.
The earth will perhaps be warmer by about 7 degrees centigrade. At the South Pole and the North Pole, the ice will melt (融化). The sea level (海平面) will rise by about 7meters. As a result, water will cover cities like London, Tokyo and New York. Some ports and towns along the coasts will disappear under water.
Some other scientists think that the dust, smoke and pollution from coal, wood and oil fires will block out the sunrays(紫外线). Then the earth will become colder and great sheets of ice will cover Europe and North America.
When chemicals in the air mix with rain, we have acid (酸) rain. Acid rain can bring us great harm. It destroys forests and kills life in lakes and rivers.
People are beginning to see how serious the problem is. They find it important to work with nature instead of against it. They are trying to save the earth in many different ways. But one of the most important things to do is to make people understand that saving the earth is saving ourselves.
