UAE has those silly palm island suburbs near Dubai, so they have a bit to lose. As far as the strait traffic being mostly oil, it would be almost trivial to build pipes and rails across to a port like, say, Khor Fakkan and transfer oil to sea tankers and containers from sea freighters, keeping all the gulf traffic inside the gulf. As far as the interior water level, the Shatt is the main feeder, so just building a pipeline upstream to draw fresh water out (giving Iraq a hand in the game) to distribute to other countries, thus regulating the level in the gulf.
The real irony, though, is that their product is what is putting their fancy shit in peril. They have to ship oil to maintain their wealth, which then has to go to maintaining the dike to control the effects of their product on their own comfort.
The main near term consequence of global warming in the US will be massive increases in air conditioning. Triggering even more fossil fuel consumption to drive the AC.
I was primarily concerned with the relative scaling (which is more or less independent of the exact shape of the wall), rather than the absolute magnitude. And we see that walling the strait is going to be extremely more difficult than walling the entire coastline, just in terms of raw materials.
But think of all the construction jobs global warming will be giving us! [/broken window fallacy]
If the Gulf has a net evaporation loss, then the material for the dam should be troweled out of its floor. Increasing its depth, and thus making it colder, would mitigate the loss, at least a little.
Would that have an effect though? Sure a tiny amount of colder water would flow in from the Indian ocean, but evaporation happens at the surface which would quickly reach the same equilibrium as before. And even if it was a factor, the volum of such a dam would be an insignificant change in the volume of the gulf.
