1. The phenomenon whereby the earth's atmosphere traps solar radiation, caused by the presence in the atmosphere of gases such as carbon dioxide, water vapor, and methane that allow incoming sunlight to pass through but absorb heat radiated back from the earth's surface.
2. A similar retention of solar radiation, as by another planet or in a solar panel.

heating of the atmosphere resulting from the absorption by certain gases of solar energy that has been captured and reradiated by the earth's surface.

Greenhous gas
Carbon dioxide is the greenhouse gas of most immediate concern, because it is the most concentrated in the atmosphere and because it can persist for over 100 years in the atmosphere once emitted. On a per molecule basis, other gases can trap even more heat than carbon dioxide. The overall measure of a gas’s ability to contribute to global warming is called the Global Warming Potential (GWP) which measures the combination of the gas’s ability to trap solar radiation as heat and the length of time it persists in the atmosphere. The GWP of a gas is calculated relative to carbon dioxide's GWP. As the right hand column of the table shows, most other greenhouse gases have far greater GWPs than carbon dioxide. Human combustion of fossil fuels for energy is the primary source of atmospheric greenhouse gases. More recently, the production of the extremely high-GWP man-made gases has been growing at a much faster rate than carbon dioxide emissions. To understand how fossil fuel