Climate change is currently being caused by human activity. Anthropogenic refers to the impact of human activities on nature. Energy-related activities (e.g., fossil fuel burning in the electric utility and transportation sectors), agriculture, land-use change, waste management and treatment operations, and different industrial operations are all examples of anthropogenic causes.

By their very nature, air pollution sources can be divided into three categories: physical, chemical, and biological sources, natural and anthropogenic sources, and climate change-relevant or non-relevant sources. Physical pollution of the atmosphere occurs as a result of energy inputs such as sound and heat. Direct thermal pollution, whether natural or artificial, is the most significant physical pollution source. Heat (caloric input) from industry, households, agriculture, and transportation alters the local climate, and air from the lower atmosphere has a higher local temperature. Indirect thermal pollution occurs in the troposphere as a result of the greenhouse effect, and is linked to chemical anthropogenic pollution and its evolution in relation to greenhouse gases. 

Chemical pollution of the atmosphere is caused by the addition of chemical compounds to natural air constituents, and it can be of both natural and anthropogenic origin. Natural chemical pollution sources, such as volcano eruptions, natural decomposition of organic substances, or fire (naturally occurring), on the other hand, are not of major concern because they are part of the natural environment's equilibrium. However, anthropogenic chemical pollution is a major concern because its sources are increasing in number and concentration with the global human population and our ever-increasing energy demand.

Anthropogenic chemical pollution knows no boundaries, and wherever pollutants are released into the atmosphere, they have an impact on the global environment. The most important sources are the combustion of fossil fuels to generate energy (heat and electricity), major industrial processes (such as the metallurgy or cement/construction industries), and transportation.