Heat energy comes to the Earth as sunlight and leaves in the form of infrared radiation, but greenhouses gases trap some of the radiation before it can escape the atmosphere again, leading to the "greenhouse effect." This gives the atmosphere a great deal of its ambient warmth. However, as greenhouse gases have increased their presence in the environment, the temperature of the Earth has risen as a result.
The term "greenhouse effect" comes from the idea that the Earth's atmosphere works in much the same way as a man-made greenhouse. This structure is made primarily of glass, permitting sunlight to come in but trapping the resulting heat inside the structure. The "greenhouses gases" come from a number of sources but, in general, they consist of nitrous oxide, methane, carbon dioxide and the gases that go into aerosols.
Since industrialization began around 1850, levels of greenhouse gases in the environment have gone up approximately 25 percent. The arrival of fossil fuels and the need for electricity meant that the consumption of energy would lead to greater greenhouse gas emissions. The challenge for government planners is to find a happy medium between development and environmental protection.