title: Analytic investigation of climate stability on Titan: sensitivity to volatile inventory.
abstract: We develop a semiempirical grey radiative model to quantify Titan's surface temperature as a function of pressure and composition of a nitrogen-methane-hydrogen atmosphere, solar flux and atmospheric haze. We then use this model, together with non-ideal gas-liquid equilibrium theory to investigate the behavior of the coupled surface-atmosphere system on Titan. We find that a volatile-rich Titan is unstable with respect to a runaway greenhouse-small increases in solar luminosity from the present value can lead to massive increases in surface temperature. If methane has been photolyzed throughout Titan's history, then this runaway can only be avoided if the photolytic ethane is removed from the surface-atmosphere system.
authors.affiliation: Lunar and Planetary Laboratory, University of Arizona, Tucson 85721-0092, USA. rlorenz@lpl.arizona.edu
authors.forename: R D
authors.initials: RD
authors.lastname: Lorenz
authors.forename: C P
authors.initials: CP
authors.lastname: McKay
authors.forename: J I
authors.initials: JI
authors.lastname: Lunine
mesh_terms: D001272:Atmosphere / Q000737:chemistry*; D001274:Atmospheric Pressure; D002980:Climate; D005118:Extraterrestrial Environment; D017752:Greenhouse Effect; D006859:Hydrogen / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000032:analysis; D008956:Models, Chemical; D009584:Nitrogen / Q000032:analysis; D010777:Photochemistry; D018539:Saturn; D013472:Sunlight; D013696:Temperature
chemical_list: D006859:Hydrogen; D009584:Nitrogen; D008697:Methane