Since the climate is the averages of weather conditions, each new weather condition that is different from the normal will make a small change in the climate. If, however, we start to have a lot of abnormal weather conditions, we start to think that we are experiencing climate change. Many people are concerned about climate change because they are afraid it will cause serious problems for life on our planet, such as melting of the polar icecaps and the spreading of tropical diseases. We are only beginning to understand why climate changes, but we know that the main causes are natural. Changes in the amount of energy released by the sun are one cause.
Clouds are another cause.
Humans also cause climate to change. That is because factories and cars produce more heat, and also because asphalt and cement absorb heat better than plants and trees. Cities also produce a lot of air pollution that contributes to climate change. Humans also cause climate change in rural areas when they clear forests and plant crops. Different colored crops can change the amount of energy that is absorbed by vegetation.