Climate systems are affected through both internal (natural) and external (human) processes.
One of the main causes behind global warming is greenhouse gases (GHGs), which are both an internal and external component of the atmosphere contributing to the greenhouse effect.
The greenhouse effect is a naturally occurring phenomenon whereby greenhouse gases (water vapour and carbon dioxide) prevent some of the outgoing energy that is radiated from the earth’s surface from escaping into space.
GHGs retain heat energy much like the glass walls of a greenhouse. Without this natural process the earth would be significantly colder than it currently is and life as we know it would not be possible.
Problems such as global warming begin to arise when atmospheric concentrations of GHG’s begin to increase.