A good review of the tide gauge data accuracy and sea level rise is here at WUWT. The Author’s bottom line:
- Tide Gauge data is invaluable for localities in determining tide states, sea surface levels relative to the land, and the rate of change of those levels — the only Sea Level data of concern for local governments and populations.
- Tide Gauge data is only accurate to ±2 centimeters. All derived averages/means of tide gauge data including daily, weekly, monthly and annual means are also only accurate to ±2 centimeters. Claims of millimetric accuracy of means are unscientific and insupportable.
- Tide gauge data is worthless for determining Global Sea Level and/or its change unless it has been explicitly corrected by on-site CORS-like GPS reference station data capable of correcting for vertical land movement.
- The current standard for Tide Gauge data, the PSMSL GLOSS, is not corrected for vertical land movement, all studies based on this uncorrected PSMSL data producing Global Sea Level Rise findings of any kind — magnitude or rate-of-change — are based on data not suited for the purpose, are not scientifically sound and do not, cannot, inform us reliably about Global Sea Levels or Global Sea Level Change.