The most familiar and obvious form of air pollution is smog hanging over cities. There are different kinds of pollution—some visible, some invisible—that contribute to global warming. In general, any substance that people introduce into the atmosphere that has damaging effects on living things and the environment is considered air pollution.
The term sometimes is used to refer specifically to climate change caused by human activity, as opposed to changes in climate that may have resulted as part of Earth's natural processes. In this latter sense, used especially in the context of environmental policy, the term climate change today is synonymous with anthropogenic global warming.
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use. The removal of trees without sufficient reforestation has resulted in damage to habitat, biodiversity loss and aridity. There are many causes of contemporary deforestation, including corruption of government institutions, the inequitable distribution of wealth and power, population growth and overpopulation, urbanization and Globalization.
Water pollution is the contamination of water bodies (e.g. lakes, rivers, oceans and groundwater). Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds. Water pollution affects plants and organisms living in these bodies of water. In almost all cases the effect is damaging not only to individual species and populations, but also to the natural biological communities.