Sinking coastlines mean parts of Christchurch will feel impact of sea-level rise earlier than expected
From reporter Tina Law:
Parts of Christchurch will feel the impacts of sea-level rise earlier than expected because the land is sinking, according to new data.
Large areas from Woodend to Lake Ellesmere, including Banks Peninsula, are subsiding up to three millimetres per year, which means an extra 30 centimetres of sea-level rise over the next 100 years.
The data has come from NZ SeaRise, a five-year research programme funded by the Government involving 30 local and international experts.
It has taken into account the natural rises and falls of the country’s coastline, as well as climate change and warming temperatures to project sea level rises.
Using a www.searise.nz... |new online tool|, New Zealanders will for the first time be able to see how much and how fast sea levels will rise along their own stretch of coast and in their neighbourhood.
Programme co-leader Professor Tim Naish, of Victoria University of Wellington, said 20 years ago it was thought sea-level rise was like pouring water into a bathtub – if you put more water in, it rises uniformly around the world, but Naish said it is actually much more complicated.
Sea levels are expected to rise at different rates across New Zealand and even at different levels across Canterbury’s coastline.
The largest increases in sea levels are expected to occur along the southeast of the North Island along the Wairarapa Coast.
Programme co-leader Dr Richard Levy, of GNS Science and Victoria University of Wellington, said subsidence rates along that coast were high, and sea levels could rise by well over 1.5 metres by 2100 if the least optimistic climate change scenario was followed.
Based on current international emissions reduction policies, global sea levels are expected to rise by about 60cm by 2100, but for large parts of New Zealand this could double to about 1.2m due to ongoing land subsidence, Naish said.
“We have less time to act than we thought.”
According to the data, Akaroa on Banks Peninsula would see 30cm of sea-level rise by 2040, instead of 2060. The coastline in the area is sinking by 3mm a year.
“Thirty centimetres of sea-level rise means the one in 50-year coastal storm flood will occur annually,” Naish said.
However, some areas at the top of Lyttelton Harbour have shown a rise in the land.
Land movement data was based on median numbers taken between 2003 and 2011, and does not include the impact of the Christchurch earthquakes.
The data showed New Brighton’s coastline was sinking at 0.8mm a year, but Naish said since the earthquakes it has actually been sinking at 8mm a year, twice as fast as the global sea-level rise.
“We don’t know how long this will go on for.”
Levy said he expected councils and planners to be the primary users of the new projection information, and that the finance and insurance sectors had already been asking for the data.
Naish said the new science would give time to put in place equitable and effective adaptation measures that would limit the impact of unavoidable sea-level rise.
The Christchurch City Council has already embarked on a long process to adapt the city and Banks Peninsula to climate change.
Changes to managing new developments are being made to the district plan and the council has agreed on guidelines for adapting existing areas.
Whakaraupō Lyttelton Harbour will be the first area in Christchurch to go through climate change planning, expected to start in the spring and take 18 months.
Simon Watts, observatory director at Brighton Observatory of Environment and Economics who built his home in Southshore, said it was always better to know about things rather than be ambushed, but said the devil was always in the detail.
He said there were areas in Christchurch that rose after the earthquakes and others that sunk.
“For some areas it could be good news and others it could be bad news.
“Yes, people should be concerned because if parts of New Zealand sink by 3mm a year, that is effectively doubling the rate of sea level rise for those places."
What's your favourite tomato recipe?
Kia ora neighbours. We know your tomato plants are still growing, but we're looking ahead to the harvest already! If you've got a family recipe for tomatoes, we'd love to see it and maybe publish it in our magazine to share with our readers. Send your recipe to mailbox@nzgardener.co.nz, and if we use it in the mag, you will receive a free copy of our February 2025 issue.
Warnings about scams
This Fraud Awareness Week, we’re reminding everyone to stay sharp and look out for the warning signs of scams to stop them before they start.
Here’s what to watch out for:
🔍 Unrealistic offers or promises of easy money that are too good to be true
🔍 Pressure tactics: Scammers may rush or threaten you to act immediately.
🔍 Requests for personal info: Be cautious if you’re asked for bank details, passwords, or sensitive information.
🔍 Unusual payment methods like gift cards, cryptocurrency, or wire transfers.
🔍 Unverified contacts: Emails, calls, or messages from unknown or suspicious sources.
How to protect yourself:
✅ Stop and think before sharing personal details or making payments.
✅ Don't click on any links until you know that it is safe.
✅ Verify the source: Contact the organisation directly using official channels.
✅ If something’s not right, it's OK to hang up, walk away, ignore it and move on.
If you wish to report a scam, contact Police on 105 or report it online via 105.police.govt.nz/use-105.
Older residents call for Amberley bus service
By David Hill, Local Democracy Reporter
A lack of public transport and access to healthcare were among the issues raised in recent a survey of older residents in the Hurunui district.
The Hurunui District Council surveyed residents aged over 60 during August and September, as it looks to develop an age-friendly community plan to support an ageing population.
There are currently no public bus services in Hurunui, which includes the town of Amberley, about 40km north of Christchurch.
Community development facilitator Vanessa Nelmes said public transport is a big issue for many elderly people, while accessing medical care when needed remains a concern.
While there are a number of community vehicle trusts operating in the district, respondents felt a regular bus service from Amberley to Rangiora and/or Christchurch is needed.
Hurunui mayor Marie Black has been among those advocating for a bus service, but for now Environment Canterbury says there are no plans to offer public transport in the district.
The distance to medical care in Christchurch and the lack of a dentist were also mentioned, Nelmes said.
The survey received 213 responses from residents aged from 60 to their 90s, with half coming from residents in the south ward, which includes Amberley.
Nelmes said the survey found a majority of the respondents felt confident using computers, internet and / or smart phones.
‘‘It kind of puts that myth to bed that old people don’t like using technology.
‘‘I think we really do need to change our mindset compared to what is really happening in our community.’’
Although about 50 respondents said they were not confident using technology, showing there was still a need for providing support.
The survey also asked if people would like to improve their skills with technology and it was ‘‘evenly split’’, Nelmes said.
A concerning trend in the survey was a number of respondents who said they felt socially isolated, especially those new to the community, she said.
‘‘We had half a dozen people who replied along the lines, ‘you have to put yourself out there, but it’s how to make the first step’.’’
The survey has been analysed by the age-friendly steering group, which plans to widen its membership to include different agencies such as district nursing and is seeking a rural voice, Nelmes said.
Council staff plan to do a stocktake of services available for senior citizens in the district, before beginning work on a draft age-friendly plan.
Environment Canterbury public transport strategy and planning manager Sonia Pollard said there are no plans to extend bus services into Amberley or the wider Hurunui district.
‘‘The focus for public transport improvements is on delivery of the core routes in Christchurch and the direct services between the main urban areas in Waimakariri and Selwyn districts and Christchurch City.
‘‘Service improvements are reliant on funding through local rates and the National Land Transport Programme.’’
She said routes outside large urban areas are unlikely to meet the funding criteria in the 2024/27 National Land Transport Programme.
But as part of the 2025/26 annual plan staff are considering how to best serve the rural community, including assessing new routes outside the Greater Christchurch boundary.
■ LDR is local body journalism co-funded by RNZ and NZ On Air.
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