That NASA data is bogus. It was taken from the JASON satellite with at most an “altimeter will measure sea-level variations over the global ocean with very high accuracy (as 1.3 inches or 3.3 centimeters, with a goal of achieving 1 inch or 2.5 centimeters).”
In other words, their millimter claim of accuracy is taken by a sensor that cannot measure anything under 1.3 inches at best. Also, NASA cannot measure sea height. They are merely measuring millions of points and averaging them. There are no specific points on the seas that provides references points to measure.
In no way can that system measure sea heights in millimeters. As usual with “climate change” liars, the data was manipulated to show sea heights increasing. They leveled it off and showed a drop when it was shown that many places on coastlines were not showing any increase in water height. NASA got caught lying.
I’ll ask you the same question then. Do you have a better way to measure sea level?