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
Anti-greenhouse effect Anti-greenhouse effect The anti-greenhouse effect is a mechanism similar to the greenhouse effect, but with the opposite consequence of cooling the surface temperature of a planet. If gases in the atmosphere of a planet have a lesser transmittance for inbound radiation (for instance, solar rays in the Solar System) than for outbound radiation (typically thermal radiation of the planet's surface in the infrared domain), the surface temperature at which inbound and outbound heat fluxes are at equilibrium is lower. The haze containing organic molecules in Titan's upper atmosphere absorbs 90% of the solar radiation reaching Titan, but is inefficient at