On Thu, 06 Feb 2020 18:04:28 -0000, Ralph Mowery wrote:

In article ,
says...

So how come the bar was taken to be slightly different to mean sea level pressure? Was it measured inaccurately when they invented it?

Maybe seal levels are dropping ;-)

I am sure Greta would say the air is heavier because of the CO2.

Many measurments have changed over the years. The standard meter or
foot or some length was changed not long ago and it was enough that the
US east to west coast changed by almost 20 feet.

Wouldn't you get that much by sea erosion anyway?