Research from NIWA shows the sea is creeping up, with flooding from storm surges starting to happen more frequently with king tides.
NIWA scientist Rob Bell says rises of more than a metre by 2100 can't be ruled out.
He says given 65 percent of kiwis live within five kilometres of the sea, including 12 of New Zealand's 15 largest cities, we really need to consider what rising sea levels mean for us.
"In low lying areas in some parts of New Zealand it's getting pretty close to overtopping some of the land marks, and some parts of the motorway."
Rob Bell says planners and engineers need to work around the uncertainty about how quickly polar ice sheets may melt in future.
He says planning is needed given most cities are located five-kilometres from the sea.
"Quite a few councils sort of say, 'well we'll wait around for a bit more certainty', but that's not necessarily going to happen in the foreseeable year, or two, or three."
Rob Bell says higher storm surges can damage beaches, seawalls, buildings, roads and other infrastructure.
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