OK so the oceans surface is randomly pimpled and pocked with "water domes" which measure in metres, an equatorial bulge of about half a metre (between Maine and Miami) due to rotation and never ending wave action of indeterminate height due to winds. So how do you define the "average sea level"? Let alone measure it with millimetre precision? Establishing that baseline number is necessary to be able to document any increase as predicted by global warming alarmists.
I know, we'll use a satellite based radar system! Except that's measuring a point value not an average. It is almost like measuring the average height of an American male. By the time you finish measuring all the required points, they have all changed in value.
Regards,
GtG
That system has been used for decades to seek/see the 'budge' of underwater submarines.