greenhart perhaps try some numbers, just note that GIA correction is an increase to the global mean sea level "rate". It in itself is like an acceleration(it would be 30mm/year/century in the wiki terms)
If you want you can also go another way.
An acceleration of 0.2mm/year/century would mean that the rate changed by 0.2mm/year over the 100 years. I.e. 0.002mm/year every year on average is the observed change. Now look at the GIA correction you are about to apply :)
