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Thousands of properties are at risk from rising sea levels and tides. Here's how to protect yourself against coastal erosion and inundation

Vision of giant waves at Bondi Beach

Wild swells have battered the NSW coast over the weekend, with Sydney's iconic Bondi Beach disappearing beneath raging ocean. 

Up the coast, the northern beaches also copped a beating and the surf club at Newcastle's Redhead Beach was inundated by waves, washing away the wheelchair ramp to the beach.

The conditions have sparked concerns over damage from erosion, with Waverley Council Mayor Paula Masselos warning the state's entire coastline has been affected. 

Redhead beach in Newcastle, NSW, was among coastline battered with huge swells over the weekend.  (Supplied: David Chung )

"Every beach along the New South Wales coast has significant coast erosion, from Bondi to Manly, Cronulla and up along the Mid North Coast," he said. 

And it's not just in NSW. Rising sea levels are posing a risk for properties all across Australia — now and many decades into the future. 

The latest report from the Intergovernmental Panel on Climate Change (IPCC) — the most comprehensive report on climate change ever released — estimates a sea level rise of up to 55 centimetres by the end of the century, while not ruling out a two-metre increase in the same period.

In 2009, more than a decade before the IPCC report, the federal government's now-dissolved Department of Climate Change estimated that between 157,000 and 247,600 individual residential buildings could be at risk of inundation if sea levels were to rise by 1.1 metres. 

Experts have warned that some of these homes could soon become uninsurable. In the worst-case scenario, owners could be left with properties they cannot live in, afford to fix, or sell.

Homes in Sydney's northern beaches, like this property in Narrabeen, have suffered from coastal erosion.  (ABC News: Philippa McDonald)

Even so, living by the water and the lifestyle it offers continues to attract many hopeful home buyers. And it's predicted that the trend towards remote working, fast-tracked by the COVID-19 pandemic, could inspire even more people to make a sea-change.

So, what can you do to ensure your dream home will remain so for decades to come? Here's what you need to know.

Buyers must do their own research

Climate change poses an array of risks that could impact private property. When it comes to sea level rise, the two main possibilities are erosion, when coastal foundations are worn away by tides, and inundation, which refers to flooding caused by rising sea levels.

"People need to take this issue very seriously," says Dr Karl Mallon, the chief executive of Climate Valuation — an organisation that provides climate change risk analysis to banks and insurers.

"Home buyers can't depend on insurers, banks, or councils to alert them or protect them from future problems from extreme weather or climate change."

That means doing your own research before putting down a deposit. But what should people be looking for — and where should they go for accurate information?

Organisations offering climate risk analysis to private property owners, like Climate Valuation, are one place to start. 

These services allow property buyers to search an address and receive a score for the property's climate change risk level for the present and into the future, depending on the building's location, structure type, age, and materials.

Climate Valuation's risk ratings broadly range from A to C, with detailed explanations for what each category constitutes. (Supplied: Climate Valuation)

A quick, free search could alert buyers to possible issues that require further investigation. "If you're seeing a 'C' either now, or in 2050, that's a big red flag and people can then choose to do their own research," Mallon says.

But, he adds: "Even for a really informed home buyer, getting access to the information they need to make a decision is actually quite difficult.

"At the moment, it's very much buyer beware."

One thing to consider is the property's elevation, which can typically be found in survey documentation. The higher the property's current and projected position above sea level the safer it generally will be from coastal inundation.

Some councils also have flood maps available to the public or, depending on where you plan to live, may offer sea rise maps.

When researching the risk of inundation, Mallon says it's important to consider the impact of potential storm surges as well as sea level rise over time on coastal or low lying property.

Three things to look for

The next question is what damage is likely if sea water does encroach near, or onto, the property.

Mallon says buyers should consider three key questions: 

  1. 1.Will water reach the property, either now, in a storm surge, or over the next few decades? 
  2. 2.Could water enter the home?
  3. 3.If water does get into the property, will it cause damage?

If the answer to the first two questions is yes, it's time to ask if the property has been built to withstand flooding: are the foundations elevated or is the home made of flood-resistant materials?

An example of a traditional Queenslander home, with the main structure raised on stilts.  (Wikimedia: State Library of Queensland)

For example, a traditional Queenslander home is built on raised stumps or pillars to allow water to pass under the structure. 

And certain building materials, such as fibre cement, concrete, or bricks, generally cope better with inundation than gyprock, soft woods or fibreglass.

Even if the home was originally built to be flood-safe, it's important to keep in mind that modifications may have been made to the property after it was first designed — such as a granny flat or extension under the original structure. 

Potential buyers should also look into what — if any — coastal management plans are already in place in the area, and what the council is planning to do in the future to protect assets. This may include building sea walls or barriers along an estuary.

For example, last year construction began on a controversial 1.3-metre sea wall from Collaroy to South Narrabeen in Sydney's north, designed to prevent future erosion threatening beachfront homes.

Home owners along the stretch have chipped in up to 80 per cent of funding for the project. The remaining funds will come from the state government and local council.

Why it's important to plan ahead

Climate change modelling tends to deal with dates far into the future and beyond many of our lifetimes. This makes it difficult to assess the gravity of risk facing individual owners.

Most mortgages in Australia are structured for up to 30 years, but Mallon says property owners should be thinking further ahead when deciding where to buy and build.

There are a number of reasons for this.

Firstly, sea levels may rise faster than has so far been predicted.

But more importantly, when it comes time to sell, Mallon says banks will be looking at the vulnerability of the property in the coming decades.

This means that even if the risk to a property is low when the owner wants to sell it in 30 years, the person they wish to sell it to may not be able to get a mortgage if the risk is set to increase over the next 30 years. 

This means property owners could face problems long before they've experienced the physical effects of climate change.

"You have to take a long term view because other people are taking a long term view and that's how they'll choose to value your property," Mallon says. 

Look carefully at insurance policies 

What home insurance will actually cover is another area to examine closely: does the policy include acts of the sea, such as inundation? The answer is probably not. 

The Insurance Council of Australia states that no region is currently "uninsurable" but acknowledges that "some regions may become difficult to insure in the future unless governments invest in appropriate physical mitigation and adaptation strategies". 

According to the Insurance Council, actions of the sea are generally not covered by home insurance. They urge anyone concerned about these hazards to check their policies and speak to their insurer. 

Last year, the Australian Competition and Consumer Commission (ACCC) found that extreme weather events had forced the cost of insurance up so significantly that as many as 20 per cent of residents in Northern Australia chose to go without it

"Our concern is that we are still hearing stories of people that have bought homes, they've not checked the insurability, they find that the flood cover is very expensive … or it's become very expensive," Mallon says.

"If [home buyers] go to their insurance company and ask 'will my insurance be the same in 30 years as it is today?' They won't get an answer to that question."

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