 Venus – the Queen of Greenhouse Dmitriy Titov Max-Planck Institute for Solar System Research ESAC, Spain 27 April 2010

 Temperatures on Mars, Earth and Venus I___  T ~ 500 K __I

 Solar radiation Thermalemission Basics of the greenhouse effect Wavelength, microns 10 µm0.5 µm1 µm5 µm

 Absorption bands of the atmospheric gases

 Greenhouse effect on terrestrial planets Venus – 500K Mars – 5K Earth – 40K

 Contribution of the atmospheric components to the greenhouse effect on Venus Temperature, K CO 2 – 460K H 2 O – 220K Clouds – 100K H 2 SO 4 Clouds CO 2 H2OH2O T eff ~250 K Ts ~ 750 K Bullock, 2007

 Venus climate perturbations: greenhouse effect and sensitivity to H 2 O and SO 2 variations F H2O ~ 30 ppm: non-equilibrium wrt escape t ~ few 100 MY F H2O ~ 30 ppm: non-equilibrium wrt escape t ~ few 100 MY F SO2 ~ 150 ppm: non-equilibrium wrt surface buffer t ~ 30 My F SO2 ~ 150 ppm: non-equilibrium wrt surface buffer t ~ 30 My Both H 2 O and SO 2 are cloud forming gases Both H 2 O and SO 2 are cloud forming gases Bullock & Grinspoon, 2001

 Water on Earth and Venus Similar volatile inventories at origin Similar volatile inventories at origin Present water amount: H 2 O VENUS ~ H 2 O EARTH Present water amount: H 2 O VENUS ~ H 2 O EARTH Deuterium enrichment: (D/H) VENUS ~ 150 (D/H) EARTH Deuterium enrichment: (D/H) VENUS ~ 150 (D/H) EARTH

 Water: its properties and role in climate evolution Thermodynamics Thermodynamics high condensation temperature existence of all 3 phases at “normal” temperatures Large reservoirs in the inner Solar System Large reservoirs in the inner Solar System Strong greenhouse agent in vapour phase Strong greenhouse agent in vapour phase When liquid – ability to dissolve CO 2 followed by its convertion to carbonates When liquid – ability to dissolve CO 2 followed by its convertion to carbonates Easy escape to space from the top of the atmosphere Easy escape to space from the top of the atmosphere

 Earth-like planet: greenhouse effect and water loss (2) Solar flux, W/m 2 T s < 100 C T s ~ 100 CT s >> 100 C Venus now Runaway greenhouse Moist greenhouse Ingersoll limit Earth now Kasting, 1988

 Habitability zone in the Solar System MARS EARTH VENUS MERCURY Distance, AU Runaway greenhouse Paradise Global fridge Greenhouse bath

 Plasma environment and escape processes H +, O +, He + Venus Earth