Many of NSW's iconic beaches and parks are at "extreme risk" from rising sea levels and national work is needed so the public accepts the cost of fighting erosion, a report quietly released by the state government says.
The consultants' report, released by the state government two days before New Year's Eve, has found that every single one of the about 20 beaches along 150 kilometres of central NSW's most pristine coastline, and two national parks are facing "extreme risk" of climate change.
Global warming threatened all the former Great Lake Council's beaches, including Hawks Nest, Blueys and Jimmys Beaches and One and Seven Mile National Parks, the report by BMT WBM environmental engineers warned.
"[All 20 council beaches] were found to be at extreme or high risk from coastal hazards, at present or future," the report said.
The areas were either already at extreme risk or would be by 2060 or 2100, the report said.
The CSIRO forecasts a likely rise in sea levels of between 0.45 to 0.88 metres by the end of the century.
About 70 residential properties are expected to face risks from slippage and erosion by the end of the century.
"Many of the properties at highest risk are also those with the highest property values," the report concluded.
Roads and sewerage infrastructure would also likely be damaged.
The state government is currently analysing data on sand volumes at Blueys and Boomerang Beaches before it formulates its coastal zone management plan this year.
But the report concluded that the state government could do more to support a consistent response among coastal councils and needed to consult the community about the likely cost of preparing for future rises.
"There are generally two approaches ??? accept the impact and loss of land, and shift or remove assets so that the beach can retreat," the report said. "[But] these actions can be extremely costly."
In 2012 the state government gave councils the power to set their own targets for sea-level rises as long as they accorded with credible scientific opinion.
But the report warned that flaws in beach studies about sand volumes, and different councils using different approaches to photograph and measure erosion, suggested the state or federal government should develop unitary standards for coastal councils.
"A national approach to coastal management, including a common methodology for valuing coastal assets and services, is regarded as essential," the report concluded.
A spokesman for the Office of Environment and Heritage said it worked closely with coastal councils and was jointly developing a coastal zone management plan.
"Councils can also apply for funds under the $63 million Coastal and Estuary Grants program," the spokesman said.