Rising sea levels are threatening almost 8000 homes, 76 businesses and about 100km of road in Napier.
In a landmark report released yesterday, Environment Commissioner Dr Jan Wright called for an overhaul of the way New Zealand is preparing for sea level rise.
According to the report, much of Napier has been built on land that rose out of the sea during the 1931 earthquake or has been reclaimed since that time.
"Nearly 8000 homes are less than 150 centimetres above the spring high tide mark, and a considerable area of the city, including the airport, is less than 50 centimetres above the spring high tide mark," it reads.
Dr Wright said homes, businesses and infrastructure worth billions of dollars have been built on low-lying land close to the coast.
"In time, some coastal land will become uninhabitable," she said
"At Haumoana, the shoreline has retreated 40 metres inland since the 1931 earthquake due to 70cm of land subsidence and changes to sediment supply from rivers. This erosion is almost certain to increase as the sea rises." She said the most difficult aspect was impact on people's homes, which for many are much more than financial security.
"Councils must use science that is fit for purpose, and engage with communities in a measured way and with empathy."
Napier Mayor Bill Dalton said the report was excellent work, but people should not panic because the issue was being addressed regionally.
"In the long term we need to plan for the fact that ocean levels are rising," he said.
Hawke's Bay Regional Council's group manager for asset management Mike Adye said the region has coastal hazard lines that are embedded within its regional coastal environment plan.
"We are now working with Hastings and Napier councils to develop a coastal strategy," he said.
Mr Adye referenced the commissioner's map contained in the report that claimed there are a substantial number of houses potentially affected within that 1.5m zone.
"One of the reasons we are doing the coastal hazards strategy is because Napier is absolutely reliant on the integrity of the beach barrier," he said. Napier MP Stuart Nash said the report was a "wake-up call".
"I mean huge parts of Westshore including the airport, and including a lot of the suburbs of Napier, are at risk in the next sort of 50 years.
"We have got work to do."
Tukituki MP Craig Foss said the commissioner's report was a welcome contribution to public discussion on climate change.