Most climate scientists agree the main cause ol the current global warming trend is human expansion of the "greenhouse effect" warming that result when the atmosphere traps heat radiating trom Earth towards the space. Certain gases in the atmosphere block heat from escaping, Long-lived gases, remaining semi-permanently in the atmosphere, which do not respond physically or chemically to changes in temperature are described as "forcing" climate change whereas gases, such as water, which respond physically or chemically to changes in temperature are seen as ''feedbacks." Gases that contribute to the greenhouse effect include: .Water vapor. The most abundant greenhouse gas, but importantly, it acts as a feedback to the climate...