Ocean level rise or the big freeze on half the planet?

[T1 Terry]

T1,
That’s the situation for vast swathes of Melbourne.
The area we lived in had a height above mean sea level of FOUR metres.
Climate forecasts indicate that, worst case, the area could be “extreme waterfront” properties within a century.
(ie. “underwater”!)
Best case: the water table underneath them will be about a metre or less. Good luck laying waterpipes, underground power etc for new houses in that!
The contractors building the new Westgate Tunnel are already facing huge problems with waterlogged substrate… that’s AFTER they dug through the thick layer of chemically contaminated soil on the old industrial sites.

A friend of ours in Yea built his dream house backing onto the Yea River, roughly 250 mtrs away. Asked the council what te 100 yr flood height was and built the house some 250 mtrs above that ..... it has now been flooded 3 times in a row, it wasn't even finished being repaired from the second flood when it was flooded even worse .... he has given up, insurance doesn't want to know him any more and he just doesn't want to live there any more .... no hope of ever recouping even his initial outlay ..... A very sad turn of events and it hasn't helped his mental health at all ...... You think you've gone over and above to make sure this will be your forever place, sunk all your money into it .. then .......

The house we bought on Purnong Rd Mannum, enquired about the "'56" flood height, told it never reached the road .... yet the last flood was 3.3 mtrs above normal river height, it circled the letterbox across the road and we were in the middle block that stayed above the water level, the rest of the road went under.
The 1956 flood was 5.35 mtrs, 2 mtrs higher, the house itself would have been above the water, but we would have a full moat around it ..... What do we build now there is no house? One group says there will never be another '56 flood, it would take less than 300mm sea level rise to reduce the river fall to only 670mm above the AHD sea level https://www.jurovichsurveying.com.au/fa ... %20country.

That doesn't allow a lot for drainage from Mannum to the sea, if it can't drain away then it will rise substantially if we have another flood like the last one ......
I think that might have been involved the reason why NRMA doesn't want to rebuild our house .... they couldn't very well refuse to insure it or say it was in a flood zone and never should have been built there at a later date ....
The yard in Upper Mannum should be safe though

T1 Terry

[native pepper]

Built my house 100m above sea level, 80m is the claimed worse case scenario if everything melted and as our bottom paddock is only 20m above the sea we could have a bay below us . Melting glaciers are creating many problems in lots of areas already In Europe and Asia, when they do finally melt lots of the Northern hemisphere could lose their rivers and water supplies. Very hard to predict what will happen as nature sure isn't telling us, just giving us signs of things to come. Feel really sorry for the generations after us, they may be in for some tough times climate wise.

On the other hand, increasing heavy storm downpours resulting in massive flash floods could well wipe out lots of infrastructure and living areas. Especially people are still building in what they class as idyllic places with a lovely creek, river or sea shore on the doorstep. Considering we've know about sea rise for 50 years, not very logical and councils and governments are only interests it economic growth, not logical sanity, they outcomes for many aren't good.

[supersparky]

Maybe the gubment of the future will just build a sea wall around the low bits and pump the rivers over it. We could call it Holland then.

[T1 Terry]

Maybe the gubment of the future will just build a sea wall around the low bits and pump the rivers over it. We could call it Holland then.

Funny you should say that. Mid Murray Council put in a big diam. drain that runs the length of the CBD, very close to the river edge .... but enough room for the levee wall on the river side. I believe the plan is to pump all the ground water and rain water, into this big drain, then out over the levee wall, that way half the town doesn't get flooded and the main street stays open. All those that paid the big $$ for river front properties along River Lane .... they knew where they built, council made them build any living area above the '56 flood level, so all the ground floor areas are garages and entertainment rooms, those that bought on the water front around the Marina, same story. Those with a jetty, hope it floats

T1 Terry

[supersparky]

Thats a bit like the area where I live, kinda.
Those that could afford warerfront on the Gold Coast are mostly 1.5 - 2 metres above the high tide mark. Some of the streets near our place are lower than the king tide level and from time to time you can give your car an underbody salt water wash if you aren't careful. When the big flood comes we'll all be in a spot of bother. Luckily for us, our house is about 500mm higher than all the other houses in the street.
I'll be looking at the grass from the wrong side then , I reckon, so it will be someone else's problem.

[native pepper]

Aus once had an inland sea they say, more than likely we will have another one in the future. There's areas of W Aus which are very close to sea level and inland below sea level. Be interesting to see what sea level rise would inundate parts of inland Aus, then there's the gulf country, lots of that is around sea level and runs down to lake Eyre.

[BruceS]

You just never know!!
There's a lot of sea below sea level too. Have to fill that first!
https://en-gb.topographic-map.com/map-n ... 785&zoom=4

[jon_d]

na Bruce. It's all planned.

The pot holes will eventually join up and become a big drain into the centre. .... simples.

[T1 Terry]

You just never know!!
There's a lot of sea below sea level too. Have to fill that first!
https://en-gb.topographic-map.com/map-n ... 785&zoom=4

Expand the map out till the scale reads 10kms then click on the bits with lines in them ....... add a sea level rise to more than usual rain fall in the centre bring Lake Eyre ad surrounding areas up a few mtrs, say 3 mtrs combined, see which way the water would flow, then factor in the water movement underground because of the saturated water table causing that to rise the same 3 mtrs ....... when that fills up, Lake Eyre will not only be huge, but there will be no where for it to drain away, only evaporation ..... that just leads to more rain ...... Now follow the tail from Lake Torrens to Port Augusta and check how far they are above sea level.

Now add this to the equation, from a source you might trust https://research.csiro.au/slrwavescoast ... el-change/ All those Mean Sea Level numbers

MSL
The average height of the ocean's surface, which can vary slightly over time and from place to place. In Australia, the AHD is based on a MSL value measured in 1966-1968 at 30 tide gauges around the country

The actual ocean has risen

How much has sea level risen since 1970?
Between 1901 and 2018, the average sea level rose by 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This was faster than the sea level had ever risen over at least the past 3,000 years. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022.

So, those measurements need to be adjusted from 1968 levels to 2025 levels .......

Then bring in the hypothetical loss of the Atlantic ocean currents and the warm water moving from the northern hemisphere to the southern polar caps, those changing sea levels shown on the CSIRO graph for the northern hemisphere, will become the southern hemisphere's sea level fluctuations, added to what we already have ..... that could be nasty.......

T1 Terry

[native pepper]

This is an interesting article today on this subject.

https://www.abc.net.au/news/2024-11-22/ ... /104626804

"Hundreds of polar researchers have issued an emergency statement calling for urgent action to deal with the impacts of climate change in Antarctica.

Antarctica and the Southern Ocean have been undergoing rapid and extreme changes in recent years, including unprecedented heatwaves and record-low sea ice levels."