New Zealand cities going underwater

New Zealand cities including Christchurch and Wellington could be inundated by global warming-induced rising sea levels, according to data from a National Geographic documentary.

An interactive map released with National Geographic’s Leonardo Di Caprio-produced documentary Before The Flood lets users dial-in cities around the world and shows several New Zealand cities under threat even if mid-range global warming predictions materialise.

Auckland’s 10 kilometre long coastal Tamaki Drive would submerge under rising seas.

The map indicates much of Christchurch, Napier, south Dunedin and Miramar in Wellington could be submerged under metres of water under some scenarios.

Timaru, Gisborne, Whangarei, Nelson, Whanganui and Invercargill are other cities likely to feel the effect of rising waters.

In 2016 low-lying south Dunedin was hit by floodwaters that could return, exacerbated by rising sea levels, the map indicates.

Auckland gets off comparatively lightly with the city’s narrow coastal strips buttressed by steeply rising terrain containing water rises.

On average, a 2.5 degree Celsius global temperature increase would see New Zealand coastal sea levels rise by 5.6 metres.

Most of Christchurch would be submerged by a 5.6 metre plus sea level rise.

Much of Napier which was thrust up by 1931’s Hawke’s Bay earthquake could go underwater again.

Before The Flood users can pick any location on earth, including New Zealand locations, to see how by 0.5°C increments, rising temperatures affect locations.

Victoria University climate professor Tim Naish said although “cool” websites like Before The Flood showed what incremental temperature rises would do to sea levels, uncertainty remained.

The Intergovernmental Panel on Climate Change did not include in their sea level rise predictions what a rapid retreat of Antarctica’s ice sheets would mean for sea levels.

Without Antarctica’s retreat, the panel predicted New Zealand’s sea levels would only rise perhaps 80cm.

“The bottom line is that current sea-level projections may significantly underestimate the Antarctic contribution to future sea levels by 2100 by as much as 80cm for the business as usual scenario without emissions reductions,” Naish said.

“If we don’t stabilise temperatures at two degrees we could commit the planet to 5.6 metre sea level rises.” - Stuff