Sea level rising at faster rate

WELLINGTON: The rate of sealevel rise around New Zealand has doubled in recent decades compared with the first half of last century, Stats NZ says.

The agency recently updated its coastal sealevel rise environmental indicator and found that relative annual sea levels had risen faster over the last 60 years at four coastal monitoring sites.

Stats NZ environmental and agricultural statistics senior manager Michele Lloyd said the rate had nearly doubled in the past 60 years.

‘‘Sea levels rose faster over the last 60 years, 1961 to 2020, compared with the previous 60 years, 1901 to 1960, at four main sites with records dating back to the 1890s and 1900s: Auckland, Wellington, Lyttelton and Dunedin.’’

Out of the locations monitored for the last 120 years, Lyttelton had seen the highest longterm trend in relative sealevel rise, at 2.24mm/year.

And between 1961 and 2020, the largest increase in the rate of mean sealevel rise was observed in Wellington.

Stats NZ said the relative sealevel rise included any local or regional changes in vertical land movement up or down. This could be caused by land sinking or rising due to geological causes, as well as from human activity. However, climate change was one of the main causes of sealevel rise — and it was likely to continue to contribute to the rise.

‘‘Future climate change projections indicate that sea levels will continue to rise. Rising sea levels affect coastal communities, infrastructure, coastal habitats, and biodiversity,’’ Ms Lloyd said.

Climate change was one of the main causes of sealevel rise, Stats NZ said.

‘‘As greenhouse gas emissions warm the Earth’s atmosphere, heat is absorbed by the ocean.

‘‘The expansion of sea water as it warms, combined with increased sea volume caused by the melting of glaciers and ice sheets, contribute to sealevel rise.’’ — RNZ