Greenhouse effect, a warming of Earth’s surface and troposphere (the lowest layer of the atmosphere) caused by the presence of water vapour, carbon dioxide, methane, and certain other gases in the air. The greenhouse effect is the process by which radiation from a planet's atmosphere warms the planet's surface to a temperature above what it would be without this atmosphere.. The "greenhouse effect" of the atmosphere is named by analogy to greenhouses which become warmer in sunlight. The existence of a high-altitude haze, which absorbs wavelengths of solar radiation but is transparent to infrared, contribute to an anti-greenhouse effect of approximately 9K. Radiatively active gases (i.e., greenhouse gases) in a planet's atmosphere radiate energy in all directions. Such an effect has been proposed for Saturn's moon Titan.. Save 50% off a Britannica Premium subscription and gain access to exclusive content. Premium Membership is now 50% off! Our editors will review what you’ve submitted and determine whether to revise the article. , Titan is a body with both a greenhouse effect and an anti-greenhouse effect. The 'greenhouse effect' on Venus is particularly large for several reasons: "Venus experienced a runaway greenhouse in the past, and we expect that Earth will in about 2 billion years as solar luminosity increases". CO2 is produced by fossil fuel burning and other activities such as cement production and tropical deforestation. Fourier, however, neither used the term greenhouse effect nor credited atmospheric gases with keeping Earth warm.  The effect of combustion-produced carbon dioxide on the global climate, a special case of the greenhouse effect first described in 1896 by Svante Arrhenius, has also been called the Callendar effect. From 1859 onwards, he showed that the effect was due to a very small proportion of the atmosphere, with the main gases having no effect, and was largely due to water vapour, though small percentages of hydrocarbons and carbon dioxide had a significant effect. The atmosphere radiates energy both upwards and downwards; the part radiated downwards is absorbed by the surface of Earth. Without the heating caused by the greenhouse effect, Earth’s average surface temperature would be only about −18 °C (0 °F). Today, 40% more CO₂ exists in the atmosphere than at the beginning of the industrial … , A concise description of the greenhouse effect is given in the, The elusive "absolute surface air temperature," see, Intergovernmental Panel on Climate Change, Top contributors to greenhouse gas emissions, FAQ 1.3 – AR4 WGI Chapter 1: Historical Overview of Climate Change Science, "Global Climate Change in the Human Perspective", "Did Venus's ancient oceans incubate life? Earth's surface, warmed to an "effective temperature" around −18 °C (0 °F), radiates long-wavelength, infrared heat in the range of 4–100 μm.  Thus greenhouses work primarily by preventing convective cooling. (Despite its name, the greenhouse effect is different from the warming in a greenhouse, where panes of glass transmit visible sunlight but hold heat inside the building by trapping warmed air.). Infrared (IR) radiation is then emitted from the surface. Of the greenhouse gases released by anthropogenic activities, carbon…, ) The temperature of the terrestrial surface environment is controlled not only by the Sun’s electromagnetic radiation but also in a sensitive way by Earth’s atmosphere.  At these wavelengths, greenhouse gases that were largely transparent to incoming solar radiation are more absorbent. Corrections? A runaway greenhouse effect occurs if positive feedbacks lead to the evaporation of all greenhouse gases into the atmosphere. This results in more warmth below.  The result, however, is an increase in temperature in both cases.  A runaway greenhouse effect involving carbon dioxide and water vapor has long ago been hypothesized to have occurred on Venus, this idea is still largely accepted.  The current observed amount of CO2 exceeds the geological record maxima (~300 ppm) from ice core data. Chapter 1: Historical overview of climate change science, "The "Greenhouse" effect and Climate Change", "Earth's Annual Global Mean Energy Budget", 10.1175/1520-0477(1997)078<0197:EAGMEB>2.0.CO;2, "NASA: Climate Forcings and Global Warming", "Synthesis Report: Summary for Policymakers", Fourth Assessment Report, Working Group I Report "The Physical Science Basis", "Climate Milestone: Earth's CO2 Level Passes 400 ppm", "A slippery slope: How much global warming constitutes "dangerous anthropogenic interference"? The sun warms the ground and contents inside just like the outside, and these then warm the air. This leads to a higher equilibrium temperature than if the atmosphere did not radiate. Swedish physicist and physical chemist Svante Arrhenius is credited with the origins of the term in 1896, with the publication of the first plausible climate model that explained how gases in Earth’s atmosphere trap heat. The origins of the term greenhouse effect are unclear. "Greenhouse effect" is actually a misnomer since heating in the usual greenhouse is due to the reduction of convection, while the "greenhouse effect" works by preventing absorbed heat from leaving the structure through radiative transfer.  According to the 2014 Assessment Report from the Intergovernmental Panel on Climate Change, "atmospheric concentrations of carbon dioxide, methane and nitrous oxide are unprecedented in at least the last 800,000 years. This can be done through the use of adequate glazing.  Each layer of atmosphere with greenhouse gases absorbs some of the heat being radiated upwards from lower layers. Let us know if you have suggestions to improve this article (requires login). Greenhouse gases include carbon dioxide, methane and nitrous oxides. It is nearer to the Sun than Earth by about 30%. , Strengthening of the greenhouse effect through human activities is known as the enhanced (or anthropogenic) greenhouse effect. The atmosphere also gains heat by sensible and latent heat fluxes from the surface. However, because Earth reflects about 30% of the incoming sunlight, this idealized planet's effective temperature (the temperature of a blackbody that would emit the same amount of radiation) would be about −18 °C (0 °F).  The surface temperature of this hypothetical planet is 33 °C (59 °F) below Earth's actual surface temperature of approximately 14 °C (57 °F). Increasing the concentration of the gases increases the amount of absorption and reradiation, and thereby further warms the layers and ultimately the surface below.. ", "The Runaway Greenhouse and the Accumulation of CO, Rutgers University: Earth Radiation Budget, Intergovernmental Panel on Climate Change (IPCC), United Nations Framework Convention on Climate Change, Reducing emissions from deforestation and forest degradation, https://en.wikipedia.org/w/index.php?title=Greenhouse_effect&oldid=987977839, Wikipedia indefinitely semi-protected pages, Wikipedia articles needing clarification from December 2019, Articles with unsourced statements from June 2017, Creative Commons Attribution-ShareAlike License.  The argument and the evidence were further strengthened by Claude Pouillet in 1827 and 1838. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. ", "Solar Radiation and the Earth's Energy Balance", Intergovernmental Panel on Climate Change Fourth Assessment Report.  Paleoclimatologists consider variations in carbon dioxide concentration to be a fundamental factor influencing climate variations over this time scale.. Updates? Greenhouse gases—including most diatomic gases with two different atoms (such as carbon monoxide, CO) and all gases with three or more atoms—are able to absorb and emit infrared radiation. The net effect of these two phenomena result is a net warming of 21K- 9K= 12K, so Titan is 12 K warmer than it would be if there were no atmosphere. Most of this thermal radiation is absorbed by the atmosphere and warms it. Clouds also absorb and emit infrared radiation and thus affect the radiative properties of the atmosphere. The atmosphere allows most of the visible light from the Sun to pass through and reach Earth’s surface. An ideal thermally conductive blackbody at the same distance from the Sun as Earth would have a temperature of about 5.3 °C (41.5 °F). ", Temperature change and carbon dioxide change, "Energy effects during using the glass with different properties in a heated greenhouse", "Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus. Most of the remaining energy is absorbed at the surface of Earth. [clarification needed]. Outside, the warm air near the surface rises and mixes with cooler air aloft, keeping the temperature lower than inside, where the air continues to heat up because it is confined within the greenhouse. A simple picture also assumes a steady state, but in the real world, the diurnal cycle as well as the seasonal cycle and weather disturbances complicate matters. French mathematician Joseph Fourier is sometimes given credit as the first person to coin the term greenhouse effect based on his conclusion in 1824 that Earth’s atmosphere functioned similarly to a “hotbox”—that is, a heliothermometer (an insulated wooden box whose lid was made of transparent glass) developed by Swiss physicist Horace Bénédict de Saussure, which prevented cool air from mixing with warm air.