The earth is 4.6 billion years old. We humans have lived on the earth for only 35 000 years, but during this period, we have changed our planet a lot in many ways. Some things we have done are very good for the earth while others are bad.
All over the world, people have cut down millions of trees. When it rains or when the wind blows, the earth is taken away. Forests have become deserts, so many kinds of animals and plants are disappearing.
Factories have also polluted the land and the water. As a result, many rivers and lakes are now dead. Around the earth, there's a special kind of oxygen called "ozone" (O3). It is important to the earth.
But now air pollution is destroying itand making a very big hole in the ozone layer.
Carbon dioxide (CO2) in the air has increased a lot. It mainly comes from burning oil, coal and wood. This has formed a blanketaround the earth. The heat from the sun can't escape so the temperature is rising. It causes the level of the oceans to rise and the climate of the earth to change.
All these problems are very serious, so we must do something now.
