Sea level rise for India since the start of tide gauge records

The global mean sea level (GMSL) changes derived from modelling do not match actual measurements of sea level and should not be trusted. Compilations of individual tide gauges of sufficient quality and length provide much more reliable information. The present work is a contribution towards a better understanding of the observed of sea levels in India and its relation to worldwide observations. The latest average relative rate of rise of worldwide sea levels from a compilation of 170 stations with more than 60 years of data returns an average relative rate of rise +0.25 mm/year. The individual rates of rise are about constant in between subsequent updates suggesting the absence of any acceleration. Observation in key sites suggests a similarly stable pattern. Along the coastline of India, the average rate of rise of sea level is +1.06 mm/year computed by considering the 11 longest tide gauges of average length 51 years. Shorter records may overrate the sea level rate of rise because of the local phasing of the quasi-60-year oscillation. In the longest records, the rates of rise are decreasing since 1955. The lack of any GPS monitoring of the vertical position of the tide gauge does not permit the determination of the absolute rates of rise.