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
Life on Titan and its moons, sent data showing Titan's surface to be extremely cold by Earth standards, and much below the temperatures generally associated with planetary habitability. Titan may become warmer in the future. Five to six billion years from now, as the Sun becomes a red giant, surface temperatures could rise to ~, high enough for stable oceans of a water–ammonia mixture to exist on its surface. As the Sun's ultraviolet output decreases, the haze in Titan's upper atmosphere will be depleted, lessening the anti-greenhouse effect on its surface and enabling the greenhouse effect created by atmospheric methane to play a