in chapter two of the Managing our Coastal Zone in a Changing Climate report a Dr Hunter, in his submission, explained‘ the rule of thumb’ for the effects of sea level rise on erosion:

if you get one metre of sea level rise—which is pretty well the upper limit of what we expect this century—that will give us a shoreline recession of between 50 and 100 metres. In other words, the shoreline on average will move back 50 to 100 metres. So if we take a middle of the range projection of half a metre for this century then we are talking about a recession of the shoreline, on average, of between 25 and 50 metres back.

This approximates the so-called ‘Bruun rule’— ‘[a]n oft cited rule of thumb is the “Bruun rule” which states that each 1cm of rise in sea level results in about 1m of coastal recession’.

Anon,
many ignore the rule of thumb. An example is the Property Council of Australia (South Australian Division)'s plan for a revitalised and rejuvenated central business district in Adelaide. Adelaide 2036: Building on Light's Vision" ignores the effects of climate change and rising sea levels on the capital city. This is so even though the report says:

we need to stop thinking about Adelaide in the 1800s and 1900s and instead focus on what our great city should be when we achieve our bicentenary in 2036...It is time to say that we will not resile from delivering a city of vibrancy and buzz; a city thatdraws the best and brightest from across Australia and across the globe. We will not go quietly into the night!

Clearly they haven't been talking to the insurance companies about the impact of Adelaide's subsiding coastline on the built environment and property values.

to be fair the Property Council was only talking about the CBD when it said that we either support a growing, changing city, or watch it die.

Their concern or vision is that the central city of Adelaide will become the dynamic and economic powerhouse of the state, providing unique opportunities for working, doing business, living, relaxing, visiting and learning.

Adaptation isn't an option for substantial chunks of the Gold Coast, where we have the sea to the east, natural and man-made rivers, creeks and canals to the west, and a couple of hundred metres of reclaimed mud flats in between. That pretty much describes the whole high-rise strip. Take ground water into account as well in the suburbs.

Some of our local roads flood every January with the king tides. Locals take it upon themselves to clear stormwater drains. One of mum's neighbours fell into a sink hole in his backyard last week. We're overdue for a king tide/storm surge combination, and everyone knows it. A few centimetres of sea level is a huge amount. I'm surprised anyone can get insurance on anything.

the either or scenario-- either support a growing, changing city, or watch it die-- doesn't make much sense when the CBD is changing rapidly. The Property Council does talk in terms of Adelaide:

growing to maximise its economic, environment and social sustainability and will reflect the aspirations of the communities of the state.

'environmental sustainability' is a hollow word if the report does not address Adelaide 2036 in the context of the effects of climate change.

Their context is their earlier report --Adelaide: The Way Forward --released in 2000-- not the current work of the IPCC. It is as if they are living in a bubble.

Lyn,

The Report says that sea level rise will exacerbate the existing problems of erosion or inundation of coastal land caused by high tides, storm surges and cyclones.Extreme sea level events will result in increased flooding (inundation) and increased erosion of ‘soft’ (sandy and muddy) coastlines.

They agree with you that:

while sea level is going to rise by what some might think is a modest amount, that small amount is going to cause a disproportionately large increase in the frequency of flooding events from the sea associated with high tides and storm surges

What that means is that if you have a flooding event which only happens every year at the moment, by the end of the century it will be happening ... every day.

Lyn
re the insurance issue you raise. No doubt the scope of insurance coverage is being reduced in some coastal areas of Australia because of climate change, particularly the increased threat of sea inundation and riverine flooding.

We do know about examples from Britain and the United States where insurance had been withdrawn or not been renewed in areas deemed prone to climate change impacts. The Insurance companies in Australia would have identified the regions and properties at risk, and , in the early stages, premiums are going to rise. That means less and less people take out insurance.

If insurers come to the conclusion that some areas are not insurable then the public purse needs to be opened. We are talking billions of dollars. The state governments are not going to like that.

Chaper 4 of the Report deals with insurance issues. What we learn is in its submission to the committee the Insurance Council of Australia said that risks identified by them as not generally covered by insurance or as ‘presently difficult to insure against’ include ‘Storm Surge, Landslip and Sea Level Rise’.

They add in their oral presentation that their most recent study shows there are 896,000 residential properties below six metres and within 3,000 metres of existing coastline, so that is a significant exposure that is out there.The value of property in Australia exposed to this risk range from $50 billion to $150 billion. So with regard to insurance coverage when the home had to be demolished because of coastal erosion there is nil coverage.

As the committee dryly observed where land is inundated or eroded by rising sea levels, coastal landowners and lenders in the banking and finance sector could face significant losses. The Australian Government is not doing anything relating to insurance coverage in the coastal zone.

"If insurers come to the conclusion that some areas are not insurable then the public purse needs to be opened. We are talking billions of dollars. The state governments are not going to like that"

Taxpayers (voters) probably wouldn't like it either. People generally don't favour forking out to rescue the wealthy.

As waterfront properties become uninsurable they'll decrease in value, which is the sort of thing that gets people's attention.

The report pointed to about 4 previous reports and noted past recommendations had been ignored or were too difficult to act on because of jurisdiction complications. Just say the recommendation for a national plan was adopted - given the way this government has responded to climate change so far...

Personally, I'd rather see this dealt with at the local level.

Lyn,
the Insurance Council of Australia talked in terms of an insurance deficit. They recommended that one way to address the deficit or gap was for the Australian Government to consider the development of a coastal land value insurance scheme to manage risks in this area.

This would involve establishing an insurance fund into which owners of low-lying coastal land would ‘pay a regular levy so as to provide compensation when rising sea levels cause their land to become permanently unusable.

Gary,
That seems fair.

Playing devil's advocate, what would happen if sea levels rise faster than expected? Even if such a scheme was started today, there'd be a substantial shortfall.

I imagine the land would have to start seriously losing value before any serious action was taken. Which is pretty much the whole story when it comes to government response to climate change overall.

Lyn,
as I understand it sea levels are rising faster than IPPC predictions-or they are in the IPPC's upper level. The best solution for property owners is to sell up before property prices start falling and move to higher ground.

Lyn,
aren't there skirmishes between property owners and local councils over stay and fight the storm surges with barriers or retreat in northern NSW ?

I seem to remember reading something about Byron Bay. There's also some conflict in East Gippsland.If I remember right, -the local council okayed a development and the planning authority in Melbourne knocked it back because of the risk from rising sea levels.

At the very minimum there should be no new development in high risk coastal areas.

Nan,
the cases you mention raise the thorny issue of planning in coastal areas. According to the Report's chapter 4 planning is a mess in the context of rising sea levels, as coastal planning guidelines have traditionally been based on a notion of static sea level both now and into the future.

So there is a need to incorporate IPCC projections of sea level rise + regional variations into local scale planning codes. That means lots of web-based tools for, and up-skilling of, planners since it is local councils who are determining coastal adaptation practices to mange risk for their local government area. Coastal adaptation relates to so-called protect, redesign, rebuild, elevate, relocate and retreat policies.

I dare say that planned retreat is rather contentious--eg., the Byron Shire Council has a long established policy of planned retreat for certain beach compartments within the shire. But this strategy lacks statutory support from the state government. Hence the conflict you refer to.

Hence the levees, pumps and seawalls that will demanded by property owners at risk of inundation or erosion

It won't be long before we see barrages at Port Philip and Botany Bay? The very low third runway at Sydney Airport will need to be elevated. The houses around Swansea Tasmania need to be relocated. A 1m sea level rise will inundate 100% of properties adjoining Lake Macquarie.

And so on and so. The sea has risen a few centimetres along much of the coast of east + southern Australia. Coastal management programs have not been designed to counter that rise, but in many cases have accommodated it without noticing what it signifies.

Nan,

The Byron Bay example has been going on for years

http://www.parliament.nsw.gov.au/Prod/parlment/hansart.nsf/V3Key/LC19961015046

As long as it's only affecting a few small areas there are enough competing interests to stall larger scale planning.

http://www.sunshinecoastdaily.com.au/story/2009/10/20/rich-to-pay-for-seawall-saviours-seawall-plan-is-f/

Money quote from that article:

“Why should everyone else pay because you wanted to live on an eroded sand dune?”

Bilongil at Byron Bay is a small, exclusive, eroded sand dune. Property owners there can afford to build their own seawalls. Although there's hardly anything left to be building seawalls on.

Anon's point on the Sydney runway is a better example of the sort of problem that could trigger meaningful action. If things got bad enough, you'd also have the Botany Bay sewage outlets backing up and flooding the carpets in Glebe. Sydney plumbing is ancient. The oil refinery at Kurnell where the sand dunes of Mad Max fame have been spirited off by Hooker Sands, would also go under. It would also be the end for the Cronulla Sharks home ground. What a shame.

The statement made about "opening the public purse" for areas that become not insurable is completely idiotic.

As with people buying in bush settings its buyer beware.