A 20th century acceleration of sea‐level rise in New Zealand

Sea levels in New Zealand have remained relatively stable throughout the past 7000 years, but salt‐marsh cores from southern New Zealand show evidence of a recent rapid rise. To date and quantify this rise we present a proxy sea‐level record spanning the past 500 years for Pounawea, southeastern New Zealand, based on foraminiferal analyses. Ages for ten sea‐level index points are established from AMS 14 C, Pb concentrations, stable Pb isotopes, pollen markers, charcoal concentrations and 137 Cs. Sea level was rising slowly (0.3 ± 0.3 mm yr −1 ) from AD 1500 to AD 1900, but during the 20th century the rate increased to 2.8 ± 0.5 mm yr −1 , in agreement with instrumental measurements commencing in 1924. This is the first sea‐level record from the southern hemisphere showing a significantly higher rate of sea‐level rise during the 20th century as compared with preceding centuries.