Tim the Plumber wrote:
Given Denmark currently spends ~$1 billion dollars USD a year on sea-level control for 5,316 km of coastline and there are 1,634,701 km of coastline in the world, there is ~308 times the coastline to control. That would be a minimum of ~$308 billion USD in cost if the numbers are extrapolated.
If you use clasic Enviromental thinking then yes. If however you use more sensable normal assesments of the world then you should understand that Denmark is low lieing and exposed to rough seas.
As would be nearly every coastline in the world with an additional 2 foot increase in sea height. There would be some which would not and there would be some which would be more impacted, which would average out.
It is also densely populated and goes to great lengths to protect it's coast very little of which is cliff or salt mash or not valuable economically.
But you stated they spent more on traffic signals at one time did you not? The neat thing about sea level rise is that it affects a lot of area and to protect a small area can cause more of a rise in other nearby areas.
Given the GDP of the world in 2011 was $6,966 billion this would be a minimum of ~5% of the world GDP each year to deal with sea level rise. This, of course could be higher in some areas and lower in others where the land is just given up to the sea. This also assumes all countries would bear the cost, which is not correct as those with coastlines will pay those costs. That is also only the cost of sea level rise and does not touch on the impacts on current agriculture or infrastructure. Some countries will not be able to afford this hit.
Second "green maths" rediculous multiple. Most of the world's coast line is not inhabited, the Arctic ocea, the Southern Ocean, the coast of western Austrailia or the coast of Western Sahara etc etc do not matter. Who cares if they move a few meters inland?
I think you have some supporting evidence to provide concerning the claim most of the world's coastline not being inhabited. I know od people who actually live on the western coast of Australia and I cannot see them holding the view you do about it not mattering.
You also ignore the problem with the harbors and ports where the rise cannot just be mitigated with a soil berm. Thus the average cost use considers such inequalities in cost.
The inhabited coastal areas are made up of:-
1 Cliff. If the sea rises 2 feet up the cliff it does not matter. No change.
What percentage of the coastlines are covered?
2 Salt marsh. The best sea defence there is. As the sea rises it will grow up with it, continuing to trap silt and slowly forming new land.
Actually the salt marsh would be covered with two feet of seawater and the new salt marsh would be on land farther inland.
3 Beach. Beaches are active things where the sand or pebles are moved about by each wave and especially by large storm waves. They are created by the sea depositing sand in that place. If the sea level gradually rises the beach will generally rise with it. Such beaches are dangerous and popular places to build homes on, the next storm might take the beach away and destroy houses near it, It is a generally good idea to spend money fighting this. If you are rich enough to buy beach front property then you should understand it comes with a price tag.
The beach will move up and inland so it is now a lot farther inland than it was before. Thus all of the property, roads, etc. which were not over about 3 feet higher than the ocean now are going to be beach in the future. The price tag is very high when talking about 2 feet, but you said there would be no problems and this sounds like an expensive problem you are trying to ignore.
4 Built enviroment. Dockyards and ports will have to be repaired and rebuilt many times over the next 100 years. That's how it goes in industrial sites. That there may be small changes in sea level will be nothing to the changes in such things as the depth of the hulls of the ships. There are plans to build "Malaka Max" ships, the biggest ships that can fit between Singapore and Jarva(?). They will need new dockyard facilities.
Draft is generally attained by dredging channels etc. not building new facilities. The increased replacement rate IS a cost you also seem to be ignoring in the claim of there not being a problem.
5 Coastal rigid defences such as the Dutch Dykes. When they are being maintained they will need a couple of feet adding on to them. Add 20% to the budget and see how it does. In 10 years time check if more is needed.
How did you arrive at a 20% increase for the Dutch? The increase in sea level will have an exponential impact on the normal maintenance levels in addition to the cost of adding the new level of protection.
None of these coastal enviroments will need much more money spent on them than is done so now. Perhaps the budget of Denmark's sea defence department will have to rise by the amount Denmark spends on painting white line on the roads. Everywhere else will get of a lot lighter.
This sounds like a WAG unsupported by anything other than wishful thinking. If they spend 1 billion dollars a year now with no increase in sea level, how do you conclude an increase of 2 feet will not cause an increase in maintenance costs or the cost of new levels?