Surging sea levels could cost the Victorian economy as much as a COVID lockdown every two years, an inquiry has been told.
Homes, farms, industrial infrastructure and conservation reserves were all at risk from coastal erosion, king tides and inundation, according to a multi-university report tabled at a state inquiry into climate resilience on Wednesday.
The report costed inaction at $337 billion by 2100, equivalent to an annual impact of 2.7 per cent of gross state product if mitigation and adaptation measures were ignored.
"That's about half the impact of COVID lockdowns on the Victorian economy per year, just due to the unmitigated impacts of sea level rise and storm surge," Victorian Marine and Coastal Council's Jacquie White told the inquiry.
"By 2040, we'll already have $123 billion in cumulative impact."
The council, along with Life Saving Victoria, commissioned the report from environmental economists from the University of Melbourne, Australian National University and University of Tasmania.
The two organisations have recommended an independent taskforce be established to guide Victoria's response to rising sea levels and storm surge, for a new coastal future fund and to build community awareness of how to adapt.
"If we act now, actions that avoid the cost of $1 of impact before 2040 is equivalent to avoiding $4 in 2070 or $10 in 2100," Ms White said.
"It will cost Victorians more to delay ... and we also have the legislative framework to build resilience and adapt."
The inquiry heard from southwest coast shire councillors where beach access points had been lost and councils that had begun building natural barriers to battle coastal erosion.
University of Melbourne environmental economics and biosecurity professor Tom Kompas noted the problem of rising sea levels wasn't limited to the coast.
"A lot of the inundation that happens here along the coast, and it happens more or less inland, it comes through rivers," Prof Kompas told the inquiry.
"Southbank isn't on the coast ... neither is Docklands, literally, but it's the Yarra that floods."
Prof Kompas said a wide range of investments, from natural barriers all the way to retreat - where entire communities are moved further inland - had to be weighed up to get the best outcomes.
Investigations had shown a number of small local government areas and suburbs could achieve significant risk reductions at relatively low costs.
