Greenhouse gas Greenhouse gas A greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range. Greenhouse gases cause the greenhouse effect. The primary greenhouse gases in Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide and ozone. Without greenhouse gases, the average temperature of Earth's surface would be about , rather than the present average of . The atmospheres of Venus, Mars and Titan also contain greenhouse gases. Human activities since the beginning of the Industrial Revolution (around 1750) have produced a 40% increase in the atmospheric concentration of carbon dioxide (), from 280 ppm
Greenhouse gas Greenhouse gases are one such mechanism. Greenhouse gases absorb and emit some of the outgoing energy radiated from Earth's surface, causing that heat to be retained in the lower atmosphere. As explained above, some greenhouse gases remain in the atmosphere for decades or even centuries, and therefore can affect Earth's energy balance over a long period. Radiative forcing quantifies the effect of factors that influence Earth's energy balance, including changes in the concentrations of greenhouse gases. Positive radiative forcing leads to warming by increasing the net incoming energy, whereas negative radiative forcing leads to cooling. The global warming potential (GWP)