Runaway greenhouse
= Runaway greenhouse
{wiki}
A <runaway greenhouse> is a loss of thermal balance when absorbed stellar power exceeds the maximum outgoing <thermal radiation> available to a water-rich atmosphere in the relevant climate state. Surface warming increases atmospheric <water> vapour and hence infrared <opacity>. The layers emitting to space need not warm as rapidly as the surface, allowing outgoing power to approach a limit rather than increasing indefinitely with surface <temperature>.
If absorbed power remains above that limit, the climate cannot settle into the same ocean-bearing equilibrium and continued warming drives evaporation. The criterion concerns the whole atmospheric <radiative transfer> problem; a large ordinary <greenhouse effect> alone does not establish a runaway. <Bond albedo>, clouds, stellar spectrum and atmospheric inventory affect its threshold and the resulting <circumstellar habitable zone>.