## 4 Discussion  
Long-term segmented tide gauges should also be compared for acceleration with the averages of long-term tide gauges in other basins to discover differences. As discussed in [21; 32], the naive average sea level rates of rise and acceleration of different data sets are characterized by small rates of rise and small accelerations despite the presence of many segmented records like Aden, Mumbai, and Karachi. The average trends and accelerations for these data sets are as follows:  
\(-\) +1.61 \(\pm\) 0.21 mm/yr and +0.0020 \(\pm\) 0.0173 mm/yr\({}^{2}\) for the _Mitrovica-23_ data set;  
\(-\) +1.77 \(\pm\) 0.17 mm/yr and +0.0029 \(\pm\) 0.0118 mm/yr\({}^{2}\) for the _Holgate-9_ data set;  
\(-\) +0.40 \(\pm\) 0.27 mm/yr and +0.0090 \(\pm\) 0.0208 mm/yr\({}^{2}\) for the _NOAA-120_ data set;  
\(-\) +1.63 \(\pm\) 0.23 mm/yr and +0.0021 \(\pm\) 0.0192 mm/yr\({}^{2}\) for the _US 39_ data set;  
\(-\) +0.49 \(\pm\) 0.34 mm/yr and +0.0063 \(\pm\) 0.0263 mm/yr\({}^{2}\) for the _PSMSL-162_ data set;  
\(-\) +1.19 \(\pm\) 0.29 mm/yr and +0.0014 \(\pm\) 0.0266 mm/yr\({}^{2}\) for the _California-8_ data set. The _NOAA-120_, _PSMSL-162_, and _California-8_ data sets have, on average, shorter lengths of tide gauge records. The naive average global sea level acceleration is therefore in the order of +0.002 \(\div\) 0.003 mm/yr\({}^{2}\). The acceleration in Karachi is unrealistic, in both the PSMSL RLR and the realigned data. The acceleration in Aden is also unrealistic in the PSMSL RLR data. Reference to prior works is sometimes relevant to better understand the pattern of long-term segmented tide gauges. This is marginally the case of the three segmented records of Aden, Mumbai, and Karachi, that have not been at the center of many studies. According to [33], the record for Mumbai between 1952 and 1962 completely reversed the entire rising trend for the previous 30 years. Based on the linear fitting of the MSL data, in the latest PSMSL RLR data set, the rate of rise from January 1932 to December 1961 was +1.56 mm/yr. When the data were realigned, it was +0.65 mm/yr. Opposite to Mumbai, [33] proposes more significant rising trends for Aden and Karachi. According to [34], the sea level rate of rise in Mumbai over the time window 1930 to 1980 was a negative \(-\)0.30 mm/yr. Based on the linear fitting of the MSL data, in the latest PSMSL RLR data set, the rate of rise from January 1930 to December 1979 was +0.52 mm/yr. When the data were realigned, it was +0.08 mm/yr. [PERSON] did not include Aden and Karachi in his analysis [34]. In contrast to [34], other studies [33; 35] computed a large sea level rate of rise for Mumbai, of +0.91 mm/yr over the time window 1878-1982. The differences [33; 36] were attributed to, \"somewhat different changes of mean annual land level (or relative sea level) obtained from the two sets of records to our generally earlier and later records\". Based on the linear fitting of the MSL data, in the latest PSMSL RLR data set, the rate of rise from January 1978 to December 1981 was +0.79 mm/yr. When the data were realigned, it was \(-\)0.24 mm/yr. [PERSON] and [PERSON] [35] did not include Aden and Karachi in their analysis. More recent works, such as [2; 3; 21; 23; 24], have been previously mentioned. In support of stable sea levels for the Indian Ocean, [27] proposed multiple lines of evidence, including coastal morphology, stratigraphy, radiocarbon dating, archaeological remains, historical documentation, and tide gauge records for Goa over the last 500 years. They evidenced an oscillatory pattern made up of a low water level in the early 16 th century, a \(\sim\)50 cm high level in the 17 th century, a level below present sea level in the 18 th century, a \(\sim\)20 cm high level in the 19 th and early 20 th centuries, a \(\sim\)20 cm fall in 1955-1962, and a virtually stable level over the last 50 years [27]. This sea level record is almost identical to those obtained in the Maldives [37; 38] and in Bangladesh [1].