What is glacial isostatic adjustment (GIA), and why do you correct for it?
since the ocean basins are getting larger due to GIA, this will reduce by a very small amount the relative sea level rise that is seen along the coasts.
the GIA correction has the effect of increasing previous estimates of the global mean sea level rate by 0.3 mm/yr.
Why on Earth would you report a number above the observed sea level? This is beyond asinine. If they keep doing this, their data will eventually show sea level higher than the West Side Highway in New York, while people will still be driving their cars there.
It is the financial equivalent of adding your withholding tax to your net income.