Wellington,  Sea levels around New Zealand have increased at a faster rate in recent decades compared with the first half of last century, the country's statistics department Stats NZ said on Thursday.

According to Stats NZ's recently updated environmental indicator Coastal Sea-level Rise, relative annual sea levels have risen faster over the last 60 years at four coastal monitoring sites throughout New Zealand, reports Xinhua news agency.

"Future climate change projections indicate that sea levels will continue to rise. Rising sea levels affect coastal communities, infrastructure, coastal habitats, and biodiversity," Stats NZ environmental and agricultural statistics senior manager Michele Lloyd said in a statement.

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, Lyttleton and Dunedin, Lloyd said.

The rate of sea-level rise has doubled in the last 60 years, compared with the mean rate from when records first began through to 1960, she said.

Of the locations which have been monitored for over 120 years, Lyttleton near Christchurch showed the highest long-term trend in relative sea-level rise of the four sites at 2.24mm/year (with a margin of error of 0.09mm).

Meanwhile, between 1961 and 2020 the largest increase in the rate of annual mean sea-level rise of all the monitoring sites was observed in Wellington, the capital.

Climate change is one of the main causes of sea-level rise. As greenhouse gas emissions warm the Earth's atmosphere, heat is absorbed by the ocean.

The expansion of seawater as it warms, combined with increased sea volume caused by the melting of glaciers and ice sheets, contribute to sea-level rise, she said.

Data for the coastal sea-level rise indicator is provided by the National Institute of Water and Atmospheric Research (NIWA) and the Land Information New Zealand (LINZ).

The coastal sea-level rise indicator was last updated in 2019.