Modified from a Newshub article (dated May 29th, 2021): Tens of thousands of Kiwi homes in low-lying coastal areas throughout the country could be deemed uninsurable over the next few decades due to increased storminess, accelerated sea-level rise and corresponding increases in coastal erosion.
In late February of this year (23-02-2021), Auckland Council recently released a public report entitled “Predicting Auckland’s exposure to coastal instability and erosion” and it reveals that large sections of Auckland’s low-lying coastline could erode back by more than 200 metres by 2130.
Richard Hills, chair of Auckland Council’s Environment and Climate Change Committee, commented that “Auckland’s long and diverse coastline makes the city extremely susceptible to instability and erosion”.
“We have a diverse coastline that includes three major harbours, sandy beaches and dunes, rocky shores and cliffs, estuaries, and offshore islands. An important part of the council’s mandate is to understand the potential risks and impacts of coastal erosion in Tāmaki Makaurau. Our coastal and geotechnical experts have recently completed research that guides us all to understand the potential impact on our coastline from forecasted sea level rise.”
The released report forecasts sea level rise and subsequent impacts on Areas Susceptible to Coastal Instability and/or Erosion (ASCIE) across four climate change scenarios:
- Low to eventual net-zero emission scenario (RCP* 2.6 M)
- Intermediate-low emissions scenario (RCP 4.5 M)
- High-emissions scenario (RCP 8.5 M)
- Higher extreme scenario, with essentially no controls on emission by 2100 (RCP 8.5 H+)
* NOTE: RCP = Representative Concentration Pathway; which is essentially a greenhouse gas concentration trajectory adopted by the Intergovernmental Panel on Climate Change (IPCC)
Around the Auckland coastline erosion susceptibility lines were predicted for 2050, 2080 and 2130, based on sea level rise forecasts determined from latest emission and sea-level data as well as national guidance from NIWA and the Ministry for the Environment. These erosion susceptibility lines now easily visible via the council’s online mapping service.
However, maps included in the report show that if global emissions remain high and we continue to track along the RCP 8.5 M scenario (high emissions), large swathes of Auckland (>100 metres back from the current coastline) will be at risk of eroding or become steadily unstable within the next 110 years.
- 2050: High-emissions scenario (RCP 8.5 M)
- 2080: High-emissions scenario (RCP 8.5 M)
- 2130: High-emissions scenario (RCP 8.5 M)
- 2130: Higher extreme scenario, with essentially no controls on emission by 2100 (RCP 8.5 H+)
The report indicates that the ASCIE for beaches would mainly be caused by more frequently occurring storm events over the next 30 years or so, but with sea level rise becoming more of a dominant factor over an extended time-frame.
According to the council report, ASCIE distances across Auckland cliffs will vary according to the geological makeup of the cliff (orientation of strata, presence of faults) its cliff height, its aspect with respect to prevailing wind and waves, and thickness and moisture retention of soils on the cliff surface.
The Auckland council is now working on a Unitary Plan change to ensure that the new coastal erosion study and map data will be considered in all future development along its coast.
Maps are one thing – but interpreting them can be another ! Preparedness for future coastal development is also vitally important BUT what about your existing coastal property ?? Do you know how it might fair in the future ?
Allow Geohazard Assessment Services to examine specific beach-front and/or cliff attributes that may enhance (or impede) erosion affecting your property ..
Contact Geohazard Assessment Services to arrange a hassle-free expert and affordable site-specific assessment to identify any potential natural hazard issues – afterall when thinking about buying a property or ‘climate-proofing’ your property – its infinitely better (for peace-of-mind) to ….. ‘know the ground beneath your feet‘