Exoplanet Climate: It Takes Nothing to Switch from Habitable to Hell
Runaway greenhouse effect can transform a temperate habitable planet with surface liquid water ocean into a hot steam dominated planet hostile to any life.
Credit: Thibaut Roger/UNIGE
The Earth is a wonderful blue and green dot covered with oceans and life, while Venus is a yellowish sterile sphere that is not only inhospitable but also sterile. However, the difference between the two is only a few degrees in temperature. A team of astronomers from the University of Geneva (UNIGE), with the support of the CNRS laboratories of Paris and Bordeaux, has achieved a world's first by managing to simulate the entirety of the runaway greenhouse process that can transform the climate of a planet from idyllic and perfect for life, to a place more than harsh and hostile.
The scientists have also demonstrated that from initial stages of the process, the atmospheric structure and cloud coverage undergo significant changes, leading to an almost-unstoppable and very complicated to reverse runaway greenhouse effect. On Earth, a global average temperature rise of just a few tens of degrees, subsequent to a slight rise of the sun's luminosity, would be sufficient to initiate this phenomenon and to make our planet inhabitable. These results are published in Astronomy & Astrophysics.