Sea levels are rising twice as fast as previously thought in New Zealand

Image: Volodymyr Goinyk – Depositphotos.

Startling new data shows that sea levels are rising twice as fast as previously thought in parts of Aotearoa, dramatically reducing the time authorities have to act.

Major new projections show that infrastructure and housing in Auckland and Wellington, as well as many other places, are at risk of flooding decades earlier than expected.

For example, in just 18 years, some areas of the capital will experience a sea level rise of 30 cmwhich will cause flood damage that occurs once a year.

City councils and other authorities did not expect to reach this threshold until 2060, halving the time needed to plan for mitigation or removal.

The new information comes from a program made up of dozens of local and international scientists called NZ SeaRise, which also includes GNS Science and Niwa.

It combines data on where the land is sinking with the latest international sea level rise projections.

The new information is likely to have serious implications for climate adaptation planning and could affect real estate prices.

Sea levels are expected to rise by half a meter globally by 2100, but in large parts of New Zealand they could more than double due to land subsidence.

Soon the impacts would be felt in parts of Auckland and Wellington.

Some areas are sinking 3 or 4 mm per year, more or less the annual rate at which the sea rises.

This doubles the amount of sea level rise and halves the time.

This threshold is important because at this level a century-old storm could occur every year, closing roads and damaging infrastructure.

He said local and regional councils had planned for that threshold to be reached by 2060, giving 20 years less to plan and adapt.

Other places on Wellington’s south coast, such as Ōwhiro Bay, Lyall Bay, and Seatoun, among others, are also sinking.

“The quite damaging impacts of sea level rise are going to be felt much sooner than we think…flooded roads and properties.

The biggest overall increases across the country are in the southeast of the North Island, along the Wairarapa coast. Sea levels here could rise more than five feet by 2100.

About 30 cm of sea level rise is unavoidable due to the amount of climate gases already present in the atmosphere.

Auckland’s housing and critical infrastructure in the crosshairs.

Vulnerable places in Auckland include the docks around the bays, Tamaki Drive, the viaduct, areas around the North West Highway at Point Chevalier, St Heliers and Mission Bay.

He said many of these places already have problems with high tides, are close to sea level and sink.

At the viaduct, the ground is sinking about 2.5 mm per year.

This nearly doubles the predicted rate of sea level rise and halves the time you have available.

In many parts of Auckland, sea levels are set to rise 30-50% faster than previously thought.

The NZ SeaRise Program online tool, showing how each home could be affected, will be available from Monday 2 May.

The entire coastline has been mapped with a separation of 2 km.

The new tool combines land subsidence data with the latest international sea level rise projections.

It will be an important new tool for municipalities, businesses and property owners to assess the risk of erosion and flooding.

There “controlled withdrawal“the abandonment of areas in which it is no longer possible or economically viable to live is already inevitable.

Climate change and warming temperatures are causing an average sea level rise of 3.5 mm per year.

This rise in sea level is caused by the thermal expansion of the ocean, by the melting of terrestrial glaciers and by the melting of the ice sheets of Greenland and Antarctica.

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