https://phys.org/news/2022-05-team-youn ... arths.html
by Southwest Research Institute
As the scientific community searches for worlds orbiting nearby stars that could potentially harbor life, new Southwest Research Institute-led research suggests that younger rocky exoplanets are more likely to support temperate, Earth-like climates.
In the past, scientists have focused on planets situated within a star's habitable zone, where it is neither too hot nor too cold for liquid surface water to exist. However, even within this so-called "Goldilocks zone," planets can still develop climates inhospitable to life. Sustaining temperate climates also requires a planet have sufficient heat to power a planetary-scale carbon cycle. A key source of this energy is the decay of the radioactive isotopes of uranium, thorium and potassium. This critical heat source can power a rocky exoplanet's mantle convection, a slow creeping motion of the region between a planet's core and crust that eventually melts at the surface. Surface volcanic degassing is a primary source of CO2 to the atmosphere, which helps keep a planet warm. Without mantle degassing, planets are unlikely to support temperate, habitable climates like the Earth's.