What is the runaway greenhouse effect? What planets does it work on and what are the consequences?
"Runaway Greenhouse Effect" is the positive feedback cycle that continuously raises an atmosphere's temperature to some new equilibrium point.
It cannot continue forever - that is not the way the mass and energy balances work. However, a new equilibrium temperature point may severely affect the planetary climate(s) and the ability of life to continue to exist.
A planet must have a sufficient atmosphere of heat-absorbing compounds and sufficient star energy to initiate and promote an unstable runaway greenhouse effect.
A normal balanced greenhouse effect is necessary for sustaining life on Earth.
The planet Venus may be a good example of an accelerated greenhouse effect that has now established a new equilibrium point.