Remember this headline “Sinking Cities” from @Stuff on 1 May 2022?  The story told of an alarming trend of land subsidence around coastal New Zealand that was doubling the rate of sea level rise and resulted in headlines like “How long will insurers stick with Petone?” 

Well you can calm the farm.

The underlying research that led to those headlines was only in draft when the original story broke.  We were subject to a week-long, orchestrated round of media interviews and gnashing of green teeth – not one journalist enquired as to whether the research had been published.  Turns out the research centred on a short-term data set taken during an ‘interseismic’ period where subsidence is indeed the usual trend.  But over the longer (20 yr+) term, uplift from slow slip events – the tiny earthquakes that occur over months to years – coupled with an earthquake, like Kaikoura, then the subsiding trend disappears.  In fact for the majority of NZ, the long term trend is that Aotearoa is rising out of the water, dragging Zealandia with it. 

Don’t sell the bach just yet!

I wrote up the longer term position in a fully referenced and peer reviewed piece entitled “Is Wellington Sinking?”, published in last month’s Geoscience Society of New Zealand’s periodical.  I was motivated to do so after a long-standing expert, Bruce Hayward, encountered similar issues with the study – but in relation to Auckland – see Is Auckland Sinking?   The ‘science’ that still hasn’t been published has been embraced by the Ministry for the Environment.  Coastal Councils, such as in Kapiti, are quietly putting warnings on LIM reports without telling homeowners, warning prospective buyers and lenders that their property is in a hazard zone with consequential impacts on home values, development constraints and insurance.

Fortunately, we now know that our cities aren’t sinking, that the novel science is not robust – in fact out by 550% when you look at the tide gauge.  Wellingtonians deserve better!

Sean Rush is an ex-Wellington City Councillor, a husband, father, hiker, cyclist with a Masters in Climate Change Science and Policy and a Masters in Petroleum Law and Policy. Sean has lived on three continents, done business in a range of locations, from Moscow to Houston to Calgary to London, but remains a kid from Hawke’s Bay who asks a lot of awkward questions!