When it came to defining height based pressure units we used the handbook of chemistry and physics to create a function of water density with temperature based on a table of pure water. At some time later we acquired a copy of SP 811 and found we were different by ~0.002% and 0.003% ...
however, a no-feedbacks climate sensitivity of 1 degC for 2XCO2 is equivalent to less than 200 m change in altitude. In that case, the lower density and temperature of CO2 at a higher characteristic emission altitude would