Climate and Habitability of Kepler 452b

The discovery of Kepler 452b is a milestone in searching for habitable exoplanets. While it was suggested that Kepler 452b is the first Earth-like exoplanet discovered in the habitable zone of a Sun-like star, its climate states and habitability require quantitative studies. Using a three-dimensional fully coupled atmosphere-ocean climate model, we perform simulations to demonstrate Kepler 452b's climates for different CO2 levels. Our simulations show that Kepler 452b is likely a habitable exoplanet if CO2 concentrations in its atmosphere are comparable or lower than that in the Earth atmosphere. However, our simulations also suggest that Kepler 452b can readily fall into the moist greenhouse state and becomes uninhabitable in the absence of silicate weathering. We will also address whether Kepler 452b can recover from the moist greenhouse state and whether the planet remains its water inventory after 6.5 billion years of life time.