Updated Tue 15 May 2012, 8:49am AEST
Thousands of mid north coast homes, worth billions of dollars will be threatened by future sea level rises and storm surges.
That is the finding of the new Climate Commission report.
The Critical Decade report says sea level rise is occurring at close to the worst case scenario, with the biggest rises happening on the southern coast.
Rises on the northern coast have been around or just below the global average.
The report concludes that a rise of between half a metre and one metre from 1990 levels is likely to happen by 2100, but more is possible.
A slightly bigger rise, of 1.1 metres, will put at risk around 4000 homes in the Great Lakes, about 1300 homes in the Greater Taree area, including at Old Bar, 1000 in the Clarence and about 800 in the Port Macquarie Hastings area.
The report also predicts a big increase in cane toads from the northern rivers to the mid north coast.
Serious erosion problems faced by beachfront property owners at Lake Cathie, near Port Macquarie have also been highlighted in the Climate Commission report.
The Critical Decade report highlights Lake Cathie, saying coastal erosion has been occurring at an average rate of 2 centimetres a year since 1940.
It says the impacts of this are likely to be exacerbated by rising sea levels.
It says by 2050 up to 16 houses could be in the erosion zone, and even more houses and roads could be destabilised.
The report suggests sea level rise is occurring at close to the worst case scenario.
It says a rise of 1.1 metres by 2100 will directly threaten more than 7000 homes between the Great Lakes and the Clarence.