Laurie Mirko doesn't need to be told about the havoc that extreme weather can wreak on coastal Kiwi communities.

Back in January, he was wading barefoot through floodwaters that reached waist-deep levels after a massive storm smashed into his small Hauraki town.

Homes were quickly swamped when seawater burst over a low bank and into Kaiaua.

Although only a water pump was damaged on Mirko's property, less fortunate residents lost fences, possessions and entire bottom levels of their homes.


"It's so flat here that when there's a king tide, there's not much difference between that and ground level."

But the deluge had made locals even more concerned about what a warmer, wilder future would bring.

Now researchers have highlighted some of the big costs that have come with weather-related events.

They found that those who were wealthier and who lived within a few kilometres of the coast were more likely to lodge claims with the Earthquake Commission (EQC).

Their study, published today by Wellington's Motu Economic and Public Policy Research, analysed more than 25,000 weather-related claims - totalling close to $300m - paid out by the public insurer since the turn of the century.

EQC covered homeowners for damage to land, and in some cases to dwellings and contents, caused by landslip, storm or flood.

Between 2000 and 2017, the mean amount paid out to claimants was $11,420 and the total paid for land damages was $199m, compared with $93m for building damage and $2.6m for damages to contents.

"Only houses with private insurance can receive a payout from EQC and there are some strict constraints on what is covered, so 41 per cent of claimants didn't get any money," said study co-author Professor Ilan Noy, who is chair in the economics of disasters at Victoria University.


Places where the median income sat within the top 40 per cent tended to report more than half of the total claims and payouts made.

"This suggests that, after extreme weather events, higher-income families make more frequent use of EQC insurance and claim more payment than the average New Zealand family."

While the reasons for that weren't clear, Noy suspected these households had better access to the system, a higher exposure due to location preferences, or higher damages caused by higher asset values.

While the average property in New Zealand is approximately 11km from the coast, the average property lodging a claim to EQC after a weather event was located only 6km away.

"We are only just beginning to provide insights about the increasing risk that current and future residential areas might face, given the possibility of increasing frequency of extreme weather events."

The paper noted how the world already appeared to be facing higher frequency and intensity of natural hazards and disasters that were linked to extreme weather and compounded by sea-level rise.

The most recent national assessment found nearly 170,000 buildings sat within 3m of the mean high water spring, exposing them not just to a potential metre of sea level rise by the end of the century, but also storm-tide and wave flooding that could reach 1-2m in exposed places.

Insurance Council of New Zealand chief executive Tim Grafton wasn't surprised by the new report's findings, noting that coastal properties tended to lower lying and with higher values.

While there were no hard estimates around what climate change would cost New Zealand's insurance industry, firms were well aware of the risks.

Flooding and storms so far this year, including that which hit Kaiaua, were estimated to have cost more than $200m in insured losses.

The new research comes weeks after a poll commissioned by the country's largest general insurer, IAG, indicated that most Kiwis now expected to see frequent and extreme storms and inundated coastlines.

Around three quarters of the respondents also agreed we'd need to rethink land use, that some people would need to move from where they currently lived, and that we'd need to support those who were worst affected.