# How much increase in the atmospheric pressure when the global temperature is elevated by 12 C?

The deep-sea temperature was $$12º$$C higher $$50$$ My ago.

I would like to know how much the atmospheric pressure at sea level had decreased and how much the water-vapour changed.
One can consider no ice-sheets and that the sea surface temperature varyed by the same amount and that by now there is $$0$$% of water vapor in the atmosphere (in fact it is between 0% and 4% function of latitude and altitude and assume the conservation of atmospheric masses of $$O_2, N_2$$).