The greenhouse effect occurs when gases such as methane, carbon dioxide, nitrogen oxide and CFCs trap heat in the atmosphere by acting as a pane of glass in a car. ³The glass² lets the sun light in to make heat but when the heat tries to get out the gases absorb the heat. Holding this heat in causes heat waves, droughts and climate changes which could alter our way of living. The main gases that cause the greenhouse effect are water vapor, carbon dioxide (CO2), and methane which comes mainly from animal manure. Other gases like nitrogen oxide and man made gases called chloro