Climate regime reached as function of the initial surface pressure and water vapor column mass () for Gl 581 c runs. Red filled disks represent simulations that reached runaway greenhouse states, and blue empty circles stand for simulation where water collapsed. The blue shaded region roughly depicts the region where collapse is observed. The gray dashed line represents the demarcation between runaway and collapse states for HD 85512 b. At higher surface pressure, redistribution is large and cold traps are less efficient. Less water vapor is thus needed to trigger the runaway greenhouse instability.