KEY POINTS:
Coastal property owners are likely to lobby councils hard for expensive protection measures such as seawalls if climate change makes their homes uninsurable, a natural disasters conference has been told.
Terry Hume, a Niwa coastal scientist, told the Auckland conference that people were still buying properties on the sea front and in high-hazard zones because they perceived the benefits outweighed the risks.
But they lacked knowledge about coastal processes and either denied risk or had blind faith that councils would help in the event of erosion.
Mr Hume said past mistakes had put coastal property in hazardous locations, too close to the sea and failing to take account of natural changes such as shoreline movement.
The level of risk was further increased as the traditional Kiwi bach was replaced by dwellings more like mansions.
A strong sense of individual property rights had to be set against the interests of the wider community which faced the possibility of rising rates to fund coastal protection and increased cost of insurance premiums.
Mr Hume said many lobby groups involved with coastal management issues were well resourced because of their often affluent and politically well-connected members.
Building insurers might not be able to calculate premiums by using historic claims experience because the past was no longer a sufficiently reliable guide to the future.
Insurance premiums might have to increase substantially, be mitigated by higher excesses or in rare cases insurance might become a thing of the past.
Mr Hume said if the insurance industry withdrew from insuring hazard-prone areas community groups would put increased pressure on councils to build hard structures such as seawalls to stop erosion and "hold the line".
It could also see unlawful actions by property owners to arrest erosion such as dumping rock.
A paper prepared by Mr Hume and Paula Blackett, policy scientist AgResearch, also warned that councils' knowledge of natural disaster risks was patchy. It said hazard mapping for natural disasters was undertaken with a different level of detail by regional and district councils.
Mr Hume said that led to a poor nation-wide picture with no standardised methodology for coastal hazard mapping and dispute among experts.
Most hazard analysis did not consider joint probabilities of events such as the occurrence of spring tides with storm surge and high waves, although such models were being developed.
Mr Hume said a sea level rise would see waves breaking higher up the shore and, with storms, would lead to more coastal erosion and flooding.
Climate Change Minister David Parker said the threat of climate change demanded policy responses which survived several electoral cycles and would require good information.
With proper planning a lot of costs from climate change could be avoided or reduced.
"Taking action now is like taking out an insurance policy for the future."
