Firstly, carbon dioxide and other waste gases that are given off in large quantities by factories and power stations as well as motor vehicles enhance the greenhouse effect, which has a negative impact on global warming. Carbon dioxide, during the burning process, creates a layer in the atmosphere which stops the heat from escaping into the space. When the heat can't escape it comes back to the earth and causes warming that leads to melting of ice caps and as result of it the sea level may raise and some part of the land such as Japan or California can be flooded.
Another problem that we have to face with is the size of ozone layer. The ozone layer that protects the Earth's surface from harmful ultraviolet radiation is damaged by CFCs (chloro-fluorocarbons). CFCs are substances that come from refrigerators, aerosol cans and other products. When we use this products, we free CFCs which go into the atmosphere and destroy the ozone layer which protects us from ultraviolet radiation. The smaller the ozone layer the stronger the radiation which leads to skin burning and some serious skin problems such as skin cancer.
At last I would like to mention deforestation as wreaking devastation around the world. It contributes to the extinction of indigenous animals, reduction of biodiversity, soil erosion as well as increased global warming as the carbon dioxide remains unabsorbed. The main problem is the exploitation of the poor countries with many wild forests by big international corporations like in Brazil where the rainforests of Amazonia are the lungs of the world.