Global Warming the development of increasing average air temperatures close to the surface of Earth. Greenhouse gases square measure chargeable for most of the ascertained temperature increase since the centre of the 20 th century, which natural phenomena like solar variation and volcanoes in all probability had a little warming result from pre-industrial times to 1950 and a little cooling result later. Most climate scientists agree the most reason for the present heating trend is human enlargement of the "greenhouse effect"1 — warming those results once the atmosphere traps heat diverging from Earth toward area. Because the climate warms, it changes the character of worldwide downfall, evaporation, snow, stream flow and alternative factors that have an effect on facility and quality. Specific impacts include: hotter water temperatures have an effect on water quality and accelerate pollution.