Trees use carbon dioxide gas to prepare their food by the process of photosynthesis. Deforestation leads to the loss of many trees as a result very less number of trees would use up the carbon dioxide gas hence the amount of this gas will go on increasing as compared to its consumption. As carbon dioxide gas is a greenhouse gas it will trap the heat rays of the sun and will increase the temperature of the surface of the earth. This phenomenon is known as global warming where the overall temperature of the earth’s surface is increased due to an increased level of greenhouse gases in the atmosphere.