New Zealand's three 'big choices' to safeguard against sea level rise, according to sustainable cities researcher

New Zealand has three "big choices" to make to safeguard against impending sea level rise, according to a researcher specialising in sustainable cities. 

New climate change research has revealed alarming predictions of 30cm sea level rise in parts of Auckland and Wellington in just 10 to 20 years, much sooner than the global prediction of 2060, due to New Zealand's position on two tectonic plates, causing sinkage. 

It won't just be waves crashing into homes but an attack from underground with water washing out drains and roads. For example, a 30cm sea level rise would be enough to incapacitate the gravity-powered stormwater system in Petone on Wellington's harbour. 

Even if the waves aren't lapping at your feet, they could erode a key piece of infrastructure near you. Eastbourne just around the Petone waterfront, for example, is relatively unscathed by sea-level rise but the only road in and out could be compromised. 

The research says Auckland's Britomart and Tamaki Drive, as well as Napier Airport, will all eventually be underwater. 

Dr Crystal Olin, a researcher with the University of Otago's Centre for Sustainable Cities, says New Zealand has three "big choices" to consider to safeguard against sea level rise.

  1. protect the coastline with sea walls and flood fences
  2. reduce the impact of coastal flooding by upgrading infrastructure - adapting buildings and raising roads, for example
  3. retreat from at-risk areas

"I'd argue the important place to start with any of those options is a shift in mindset and really thinking about getting back to nature and letting nature come back into our cities, so learning from nature rather than fearing it," Dr Olin told Newshub Late. 

"There's an opportunity now. We can think about how we might connect people with the water, so rather than hard sea walls, could we put in berms… marshlands, salt ponds and things like that?"

Dr Olin echoed the views of climate change researcher Judy Lawrence, who told Newshub's Samantha Hayes that we should build cities to absorb water, not repel it: 'sponge cities'.

"The idea of a sponge city... is it takes up water," Lawrence told Newshub.

"So, in a city where you can plant trees and have vertical gardens on buildings, have low-lying areas like some of the big parks... opened up for vegetation... so the ground becomes the sponge."

Dr Olin said the idea has merit. 

"That can have really amazing co-benefits as well, so prioritising putting in green public spaces, for example, and part of the city can also work to not only mitigate flooding and also cleanse stormwater and help manage water in general, but also help to restore biodiversity and have a positive ecological effect as well as have a positive effect on people and their wellbeing in their communities."

The Government is currently seeking feedback on its proposal for responding to climate change, with big questions around insurance, property transfer and who should pay for managed retreat.

"I need to emphasise that we are already paying for the cost and this is about reducing future liability," Climate Change Minister James Shaw said last week. 

"The cost is getting carried and those costs will increase and if we do nothing and we are just dealing with the effects of climate change via emergency response, then that is going to equate to an increase in taxes because that money has got to come from somewhere."

Over the last 10 years, climate change related floods have cost the New Zealand economy at least $120 million for privately insured damages. Economic losses from droughts have cost a further $720 million.

The Bay of Plenty town of Matatā is a prime example. Much of the town 24km to the north-west of Whakatāne was relocated between 2006 and 2021 due to increased natural threats arising from climate change. 

It has come at a cost of approximately $16.8 million and has caused years of stress and uncertainty for the community. It required cooperation and funding from Whakatane District Council, Bay of Plenty Regional Council and central government.

Dr Olin acknowledged that dealing with sea level rise will be expensive. 

"It's likely to be expensive but it depends on the route we take and there are less expensive options. I really encourage New Zealanders to take a much longer-term view," she told Newshub Late. 

"We need to think in terms of centuries instead of decades and we need to think about those future generations - our children and our children's children, and the planet. 

"It's a selfless act to think into the future but that's really what it's going to take."