Other things being equal, the more greenhouse gases there are, the greater the greenhouse effect, and the higher the Earth's temperature. This increase in average temperature is a key part of the phenomenon known as 'global warming'. The enhancement of the greenhouse effect due to the emission of greenhouse gases is one important reason why global warming could occur. Most greenhouse gases occur naturally. However, modern industry and lifestyles have led to new sources of greenhouse gases, as well as to the emission of entirely new greenhouse gases.
Water vapour comes from natural and human-induced respiration, transpiration, and evaporation.
The amount of water vapour released through evaporation increases as the Earth's surface temperature rises. Carbon dioxide . Carbon dioxide comes from the decay of materials, respiration of plant and animal life, and the natural and human-induced combustion of materials and fuels. It is removed from the atmosphere through photosynthesis and ocean absorption. Of the greenhouse gases, carbon dioxide is second only to water vapour in volume.