"Equilibrium temperature" refers to the stable and balanced temperature at which an object or system remains without any changes in its temperature over time. Full definition
The idea was that if one increases the insulation around an oven then it will reach a higher equilibrium temperature for the same energy input. (newclimatemodel.com)
Since warmer objects mean more energetic radiation, eventually a new and somewhat higher equilibrium temperature will be established. (hubpages.com)
It would be much more appropriate to refer to the equilibrium amount of increase in sea level per unit of achieved equilibrium temperature increase. (bravenewclimate.com)