Rising sea levels could leave low-lying towns such as Busselton under water by 2100 if emissions went unchecked, according to one of Australia's foremost climate change experts.
Paul Hardisty, the director of the CSIRO's climate adaptation flagship, said Australia and WA faced coastal flooding in the coming decades that could cause damage worth trillions.
Pointing to the walls that were being repaired or newly built along the Swan River, Dr Hardisty said authorities were already being forced to adapt even if most people did not notice.
He told a conference hosted by the Committee for Economic Development of Australia that sea level rises of 1m appeared inevitable.
The comments from the former senior manager at engineering firm WorleyParsons were prompted by a question from Lyn Beazley, who stepped down as WA chief scientist last year.
Responding to the question, Dr Hardisty said: "You go to Busselton, for instance, and the whole town is at half a metre of elevation and certainly well within the range, by 2070, that without sea walls they'll be under water."
"And they know it," Dr Hardisty said.
"Coastal inundation is one of the effects that played into the financial estimates of exposure… looming into the trillions of dollars across Australia.
"So it's a significant issue.
"And this is just going to keep going.
"It's basically being driven by the thermal expansion of water as much as anything else and that has got a lot of inertia behind it.
"We're going to see a metre no matter what we do."
Mr Hardisty also criticised the practice of measuring a country's success solely by its gross domestic product, saying it was flawed because it ignored the damage economic growth sometimes caused people and the environment.
Danny Price, the architect of the Abbott Government's so-called direct action plan, told the conference the policy could be just as, if not more, effective than the carbon tax and at a lower cost.
Mr Price, a founder of Frontier Economics, also savaged Clive Palmer's intervention in the climate change debate, saying his plan to have an emissions trading scheme set at zero was a "cruel hoax".
"I don't subscribe to the economic orthodoxy that carbon trading is the dominant model and the one that will prevail over time," he said.
"I don't think it will.
"In fact I think we're wasting our time on that type of arrangement.
"There are much better ways of achieving climate changes policies in Australia and elsewhere."