Rising seas are threatening to encroach on low-lying parts of Melbourne within 20 years, causing flooding and erosion in suburbs including St Kilda, Point Cook, Mordialloc, Seaford and Frankston.

Other places at risk include areas around Queenscliff and Barwon Heads on the Bellarine Peninsula; the south-west Victorian towns of Port Fairy and Portland; and Tooradin, Lang Lang and Seaspray in the state's south-east.

Melbourne bayside areas are among those ranked as at risk. Credit:Luis Ascui

A report tabled in Victoria's Parliament last week examines the myriad threats to the state’s fragile coastline, painting an alarming picture of damage to the environment and suburban Melbourne if no action is taken.

The Victorian Environmental Assessment Council report cites a 20-centimetre sea-level rise by 2040 and between 40 centimetres and one metre by century’s end.