The government's "Climate Change Risks to Australia's Coasts" report found between 157,000 and 247,600 existing residential buildings were in danger of being flooded by 2100 if seas rose by 1.1 metres (43 inches).

Major ports and other crucial infrastructure were also vulnerable, said Climate Change Minister Penny Wong.

"Sea-level rise, more intense cyclones and ocean acidification will potentially increase the capital and operating costs of ports quite significantly by mid-century," said Wong, releasing the report.

"A number of airports are also located in low-lying areas in the coastal zone, and are at risk of inundation in the coming century," she added.

Billed as the most comprehensive and scientifically-based look at the issue to date, the report found 120 ports, five power stations and substations and three water treatment plants were within 200 metres (yards) of the coast.

The 1.1 metre rise was a "plausible" estimate of likely sea-level elevation due to climate change, based on the most recently published scientific data, the report said.

Sydney Airport, Australia's largest and gateway to almost 32 million people a year, was particularly vulnerable because of its bayfront location, the report warned.

"The combined effects of sea-level rise, storm surge and tidal action resulting in significant inundation ... could effectively close the airport," the report said.

Wong said some of the changes flagged in the report were already happening and its findings could not be ignored.

"This report highlights the need for planned, coordinated action to help manage the risks," Wong said.

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