Figure 15: Global sea level measurements from the Topex/Poseidon satellite altimeter for 1993 to 1997 (43). The instrument record gives a rate of change of minus 0.2 mm per year (43). However, it has been reported that 50-year tide gauge measurements give plus 1.8 mm per year. A correction of plus 2.3 mm per year was added to the satellite data based on comparison to selected tide gauges to get a value of plus 2.1 mm per year or 8 inches per century (43).