IN DEPTH: New Zealand faces major sea rise much sooner than we thought
The sea level is rising twice as fast as previously forecast around parts of New Zealand, according to research published by NZ SeaRise, putting our two largest cities at risk decades earlier than expected.
Government-backed data amassed from around the country’s coastline found some areas are already sinking 3-4mm per year, speeding up a long-expected threat.
The projections, labelled “a bit terrifying” by one expert, are the result of an extensive five-year, government-funded research programme NZ SeaRise, that was the combined work of dozens of local and international scientists. Their prognosis means authorities have much less time than expected to introduce climate adaptation plans, including relocating coastal communities.
NZ SeaRise co-leader Tim Naish, a professor at Wellington’s Victoria University, said while the global sea level is expected to rise about 0.5 metres by 2100, for substantial parts of New Zealand it could be closer to 1 metre because the land is sinking at the same time.
It is stark news for the capital city, Wellington, which could expect a 30cm sea level rise by 2040 – a level that had not been expected before 2060. With that rate of rise, Wellington residents can expect once-a-century flood damage every year on average.
“We have less time to act,” Naish said. “You are going to see the impacts of quite damaging sea level rise much sooner than we thought. Roads and properties will be inundated. Yes, it is a bit terrifying but there is still time and I think that is the way to look at it.
Data shows the southeast coastline of the more populated North Island is the most exposed, but numerous seaside communities and towns will be hit.
Auckland, which with 1.7 million residents is comfortably the country’s largest city, is especially vulnerable.
It is predicted the sea level will rise 50 per cent faster in the city’s downtown waterfront and several central-city suburbs, with wide-ranging implications for house prices and insurance rates.
NZ SeaRise has developed an online tool to let residents and authorities check forecasts for their stretch of coast – allowing them to assess the risk of flooding and erosion.
Prime Minister Jacinda Ardern said adaptation planning was already underway, including budgeting for the relocation of some communities and infrastructure away from vulnerable coastlines.
“The first port of call isn’t necessarily managed retreat because there is a range of options that can be used,” she told Radio New Zealand.
“We’re working alongside local government and insurers to work through who bears the costs of some of these options. The cost that needs to be borne won’t fall on one party.”
Ardern said New Zealanders should not accept that sea level rises are inevitable beyond those predicted for the near term, and every citizen should do all they can to reduce emissions and diminish the effects of climate change.
The NZ SeaRise: Te Tai Pari O Aotearoa programme has released location-specific sea level rise projections out to the year 2300 for every 2 km of the coast of Aotearoa New Zealand. These projections can be accessed through a new online tool developed by Takiwā, a data management and analytics platform.
For the first time, New Zealanders will be able to see how much and how fast the sea level will rise along ‘their own’ stretch of coast and in their neighbourhood. The tool allows users to click on a particular location on the coast and see how much the sea level is expected to rise, and by when, under different climate change scenarios.
Climate change and warming temperatures are causing sea levels to rise, on average, by 3.5 mm per year. This sea-level rise is caused by thermal expansion of the ocean, melting glaciers, and melting of the Greenland and Antarctic ice sheets.
Global Sea-level Rise
The climate is changing and the world is warming. The oceans have taken up most of the additional heat so far, and as the water warms up, it expands. In combination with water from the melting of land-based ice, this causes rising sea levels. Read More
New Zealand Sea-level Rise
The sea around New Zealand rose, on average, by 1.7mm per year from 1900 to 2008. But at the same time, the land is going up in some places and down in others. We are putting both of these changes together to accurately predict total sea-level rise at a local scale. Read More.
Community Impacts
Rising seas have local impacts. This includes flooding, rising groundwater levels, coastal erosion, and salinization of wetlands and aquifers. We are working with partners – regional councils, iwi and government agencies – to look at specific local impacts of projected sea-level rise. Read More.
About NZ SeaRise: Te Tai Pari O Aotearoa
NZ SeaRise is a five-year research programme funded by the Ministry for Business, Innovation and Employment Endeavour Fund. It brings together 30 local and international experts from Te Herenga Waka-Victoria University of Wellington, GNS Science, NIWA, University of Otago and the Antarctic Science Platform to improve projections of sea-level rise in Aotearoa New Zealand. The sea-level projection and mapping tool was developed by Takiwā, a Māori-owned data management and analytics platform. An update to the Coastal Hazards Guidance for Local Government on how to use the new projections for planning has been co-produced with the Ministry for the Environment.