Average sea levels may not change significantly in the next few years but they will accelerate in the future, a coastal hazard consultant has warned.
"We will see impacts in our lifetime," said Doug Ramsay, manager of Niwa's Pacific activities.
"We know sea levels are going to rise but not how quickly."
However, rises of more than a metre by 2100 could not be ruled out and should at least be considered in assessing the vulnerability of existing coastal development.
The biggest challenge New Zealand faced was how to deal with the seaside developments established over the last 60 or so years, before there was much awareness of climate control, he told APNZ.
Planners now were better informed and prospective buyers of coastline property should do their homework.
"If an area was getting flooded in the past, it certainly won't improve in the future."
Mr Ramsay said any erosion was also likely to continue.
"Talk to your council. Look at old photos," he advised.
There was tension between long-term planners trying to do what was right and those who wanted things to happen in their lifetime. Decision-making was also affected by politicians' short election time frames.
Mr Ramsay said consultation should be held among all the "different communities of interest," including councils, developers and insurers.
"It needs greater discussion, rather than in pockets."
A keynote speaker at a "meeting the challenge" conference on sea level rise in Wellington today, he told delegates New Zealand trends were similar to the global average, "so we can really adopt global projections till monitoring shows otherwise".
Another speaker, Martin Manning of the Climate Change Research Institute at Wellington's Victoria University, said planning needed to take account of a continually changing environment.
"Decision-making has to be done quite a while before it (sea level rise) happens. We have to plan for a future a long way out there."
He said rising seas could happen "quite rapidly" and preparations needed to be in place.
Dr Manning's colleague, Judy Lawrence, told the conference there was an urgent need for wider co-operation in identifying risks and how to avoid and prevent damage from future hazards.
Lessons could be learned from earthquake-stricken Christchurch.
"We need an approach that is aligned between the three levels of government - local, regional and national," she said.
They should talk to each other and to the public about how to deal with the long-term hazards posed by climate change.
The lessons were there from the Christchurch earthquakes on how frameworks, roles and responsibilities might be redesigned in anticipation of how to cope more flexibly with future disaster.
"It is not if, but when, it will happen," said Ms Lawrence.