A major new climate risk assessment has delivered a sobering warning for coastal Australia: more than 267,000 properties and upwards of two million hectares of land across the country could face flood damage by the year 2100 if sea levels continue to rise at current projections. The findings, drawn from a nationwide analysis by Australian researchers, add fresh urgency to a debate that has simmered in coastal communities from Queensland to Western Australia for more than a decade.

For Western Australians, the numbers are not an abstract, far-off problem. Perth’s low-lying river suburbs, the Peel region around Mandurah, and stretches of the state’s south-west coastline have already recorded measurable erosion and storm-surge damage in recent years. The new research reinforces what many coastal councils have been budgeting for quietly behind the scenes: managed retreat, sea walls, and stricter planning controls are no longer contingency plans, they are becoming standard practice.

What the Research Found

The study combined elevation mapping, tidal modelling and population data to estimate which parcels of land sit within reach of extreme sea-level events by the turn of the century. Researchers found that the exposure is not limited to a handful of high-profile hotspots. Instead, risk is spread across hundreds of local government areas, with the heaviest concentrations in low-lying estuarine areas, river deltas and sandy foreshore suburbs where homes were built close to the water in the twentieth century, long before contemporary flood mapping existed.

Crucially, the modelling does not assume a single catastrophic event. Instead it factors in the compounding effect of rising baseline sea levels combined with the kind of storm surges and king tides that already occur periodically along the Australian coast. As the baseline creeps upward, events that were once rare start to happen more frequently, turning what used to be a one-in-a-century flood into something closer to an annual inconvenience, and eventually a permanent inundation.

Why Western Australia Should Pay Attention

Western Australia’s coastline stretches more than 20,000 kilometres, and a significant share of the state’s population lives within a few kilometres of the ocean or an estuary. Suburbs built along the Swan and Canning rivers, the Peel-Harvey estuary and the beaches of the Mandurah and Rockingham corridor are routinely cited by coastal engineers as among the most exposed in the state to a combination of sea-level rise and storm-driven erosion.

The WA Department of Transport has previously flagged erosion hotspots along the metropolitan coast, and local governments including the City of Mandurah and the Town of Cottesloe have already begun incorporating coastal hazard setbacks into their planning schemes. What the new national data adds is scale: it places Western Australia’s local challenges inside a much bigger national picture, making the case that piecemeal, council-by-council responses may not be enough on their own.

The Economic and Insurance Angle

Beyond the environmental impact, the financial exposure is significant. Insurers have already begun reassessing premiums in flood-prone postcodes across Australia, and mortgage lenders are increasingly factoring long-term climate exposure into valuations. Property owners in identified risk zones may eventually face higher insurance costs, more stringent building requirements, or in some cases difficulty securing cover at all. For state and local governments, the cost of protective infrastructure such as sea walls, dune restoration and stormwater upgrades runs into the billions of dollars nationally, a bill that will need to be shared between different tiers of government and, in some cases, private landowners.

What Can Be Done

Coastal adaptation experts generally point to a mix of responses rather than a single fix. Soft engineering solutions, such as restoring dunes and replanting coastal vegetation, can buffer wave energy at a lower cost than concrete barriers. Where retreat is unavoidable, forward planning, land swaps and staged buyback schemes tend to produce better outcomes for affected communities than emergency relocations after a disaster strikes. Updated flood mapping, tighter development controls in vulnerable zones and continued investment in early-warning systems for storm surges are also central to the response being recommended by researchers and coastal management bodies alike.

For now, the takeaway for Western Australian residents and policymakers is clear: coastal flood risk is a long-term planning issue rather than a distant hypothetical. With more than two million hectares of Australian land identified as exposed by 2100, the conversation about how, when and where to build along the coast is likely to intensify in the years ahead, and WA’s own vulnerable stretches of coastline will be part of that national reckoning.

The Bigger Picture

Climate scientists stress that the figures behind this kind of research should be treated as a planning baseline rather than a fixed prediction, since the exact pace of sea-level rise depends heavily on future global emissions trajectories that are still being negotiated through international climate processes. Lower-emissions scenarios modelled by the same body of research suggest a meaningfully smaller, though still significant, increase in exposed land and property, underscoring why global mitigation efforts remain directly relevant to local coastal planning decisions in places like Western Australia.

In the meantime, WA’s Department of Transport and coastal local governments continue to update erosion hotspot mapping on a rolling basis, giving residents and prospective buyers a way to check exposure for specific properties before committing to a purchase. Real estate agents in some coastal suburbs report that buyers are increasingly asking about flood and erosion risk during the purchase process, a shift from a decade ago when the question rarely came up outside of a small number of well-known hotspots.