Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus.

A one-dimensional climate model is used to study the response of an Earth-like atmosphere to large increases in solar flux. For fully saturated, cloud-free conditions, the critical solar flux at which a runaway greenhouse occurs, that is, the oceans evaporate entirely, is found to be 1.4 times the present flux at Earth's orbit (S0). This value is close to the flux expected at Venus' orbit early in solar system history. Is is nearly independent of the amount of CO2 present in the atmosphere, but is sensitive to the H2O absorption coefficient in the 8- to 12-micrometers window region. Clouds should tend to depress the surface temperature on a warm, moist planet; thus, Venus may originally have had oceans if its initial water endowment was close to that of Earth. It lost them early in its history, however, because of rapid photodissociation of water vapor followed by escape of hydrogen to space. The critical solar flux above which water is rapidly lost could be as low as 1.1S0. The surface temperature of a runaway greenhouse atmosphere containing a full ocean's worth of water would have been in excess of 1500 degrees K--above the solidus for silicate rocks. The presence of such a steam atmosphere during accretion may have significantly influenced the early thermal evolution of both Earth and Venus.

[1]  R E Roberts,et al.  Infrared continuum absorption by atmospheric water vapor in the 8-12-microm window. , 1976, Applied optics.

[2]  V. Safronov,et al.  Evolution of the protoplanetary cloud and formation of the earth and the planets , 1972 .

[3]  Syukuro Manabe,et al.  Thermal Equilibrium of the Atmosphere with a Given Distribution of Relative Humidity , 1967 .

[4]  J. Howard.  Near-infrared transmission through synthetic atmospheres / , 1954 .

[5]  D. Gough.  Solar interior structure and luminosity variations , 1981 .

[6]  J. Kasting,et al.  Evolution of a steam atmosphere during Earth's accretion. , 1988, Icarus.

[7]  A. Watson,et al.  Temperatures in a runaway greenhouse on the evolving Venus: implications for water loss , 1984 .

[8]  D. Hunten.  The Escape of Light Gases from Planetary Atmospheres , 1973 .

[9]  G. Wetherill,et al.  Occurrence of Giant Impacts During the Growth of the Terrestrial Planets , 1985, Science.

[10]  V. Ramanathan,et al.  The Effects of Moist Convection and Water Vapor Radiative Processes on Climate Sensitivity , 1984 .

[11]  A. Hou,et al.  The Role of Convective Model Choice in Calculating the Climate Impact of Doubling CO2 , 1982 .

[12]  J. Pollack.  A nongrey calculation of the runaway greenhouse: Implications for Venus' past and present☆ , 1971 .

[13]  D. Hunten,et al.  ESCAPE OF ATMOSPHERES AND LOSS OF WATER , 1989, Origin and Evolution of Planetary and Satellite Atmospheres.

[14]  JOHN S. Lewis,et al.  Cometary Water on Venus: Implications of stochastic impacts , 1988 .

[15]  Paul B. Hays,et al.  A negative feedback mechanism for the long‐term stabilization of Earth's surface temperature , 1981 .

[16]  I. Vardavas,et al.  Atmospheric temperature response to variations in CO2 concentration and the solar-constant , 1985 .

[17]  M. S. Matthews,et al.  Planetary Science. (Book Reviews: Origin and Evolution of Planetary and Satellite Atmospheres) , 1989 .

[18]  Lester Haar.  Nbs/Nrc Steam Tables , 1984 .

[19]  M. H. Hart,et al.  The evolution of the atmosphere of the earth , 1978 .

[20]  G. Herzberg,et al.  Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing PathsXI. The Spectrum of Carbon Dioxide (Co 2 ) below 1.25μ* , 1953 .

[21]  John S. Lewis,et al.  Low temperature condensation from the solar nebula , 1972 .

[22]  T. Ackerman,et al.  Climatic consequences of very high carbon dioxide levels in the earth's early atmosphere. , 1986, Science.

[23]  M. J. Newman,et al.  Implications of Solar Evolution for the Earth's Early Atmosphere. , 1977, Science.

[24]  Non‐selective absorption by atmospheric water vapour at visible and near infrared wavelengths , 1979 .

[25]  D. E. Burch,et al.  Investigation of the Absorption of Infrared Radiation by Atmospheric Gases: Water, Nitrogen, Nitrous Oxide , 1970 .

[26]  I. Vardavas,et al.  Solar and terrestrial parameterizations for radiative-convective models , 1984 .

[27]  F. X. Kneizys,et al.  Convolution algorithm for the Lorentz function. , 1979, Applied optics.

[28]  M. Gaffey,et al.  The Chemical Evolution of the Atmosphere and Oceans , 1984 .

[29]  F. X. Kneizys,et al.  FASCODE - Fast Atmospheric Signature Code (Spectral Transmittance and Radiance) , 1978 .

[30]  Dudley A. Williams,et al.  Infrared Transmission of Synthetic Atmospheres.* I. Instrumentation , 1956 .

[31]  T. Matsui,et al.  Evolution of an impact-induced atmosphere and magma ocean on the accreting Earth , 1986, Nature.

[32]  C. Tomasi.  Weak absorption by atmospheric water vapour in the visible and near-infra-red spectral region , 1979 .

[33]  C. E. Moore,et al.  The Solar Spectrum 2935 Å to 8770 Å , 1966 .

[34]  J. Kasting,et al.  Mass fractionation during transonic escape and implications for loss of water from Mars and Venus , 1986 .

[35]  A. Coradini,et al.  Earth and Mars: early thermal profiles , 1983 .

[36]  A. Watson,et al.  Venus Was Wet: A Measurement of the Ratio of Deuterium to Hydrogen , 1982, Science.

[37]  T. Ackerman,et al.  Response of Earth's atmosphere to increases in solar flux and implications for loss of water from Venus. , 1984, Icarus.

[38]  T. Matsui,et al.  Impact-induced atmospheres and oceans on Earth and Venus , 1986, Nature.

[39]  A. Ingersoll.  The Runaway Greenhouse: A History of Water on Venus , 1969 .

[40]  L. J. Cox.  Optical Properties of the Atmosphere , 1979 .

[41]  Owen B. Toon,et al.  A global average model of atmospheric aerosols for radiative transfer calculations , 1976 .