Average global sea level, while important to those who worry about AGW and the doom they
believe is to come, relies on satellite estimates which have a lot of error built into them, and can't be related sensibly to tide gauges, though there have been attempts.
You know, I would have a lot less trouble
believing climate scientists could actually measure changes in
global average sea level to within a milimeter, if I didn't know how badly they overstate their confidence in «
global average temperature» in all its many manifestations, with all its many assumptions, models and WAGs.