In what it calls “the craziest, most megalomaniacal scheme from the 20th century you never heard of”, Strange Maps reports on Atlantropa, a scheme in the 1920s to dam the various entries to the Mediterranean Sea. The idea, brainchild of Herman Sörgel, was to lower the elevation of the sea by as much as 200 meters, and then use the elevation difference to generate hydroelectric power. Oh, and do a bunch of Eurocentric rubbish to Africa (get in line).
One of the obvious issues with the plan is the havoc it would cause on the existing coastline. Venice is no longer really Venice when it’s 200 meters above sea level, for example. Also, the increased water salinity would probably kill what’s currently living in the water. These reasons, among others, are cited as example of why “Sörgel’s plan would be considered outdated today”. I, however, think now might be just the right time for damming the Mediterranean.
If global warming doomsday predictions are to be believed, global sea levels will rise by some non-trivial amount in the next century. You can find maps showing the effects of 100m rises, for example.* That being the case, if the Atlantropa plan could be recast as a way to keep the levels of the Mediterranean as they are now it might be more palatable.
The idea would be to build the dams assuming the ocean’s level will rise. As that happens outside the dam, make adjustments to keep level on the inside the same. Thus, the coastline of the Mediterranean is preserved, while the rest of the world drowns.
Alternately, using the same dam system, you could actually turn the Mediterranean into an elevated bowl, instead. By pumping water from outside the dam to fill up the bowl, you turn the Mediterranean into a large store of water, protecting the rest of the world from the rising sea level instead. This would come at the cost of drowning most of the cradle of Western Civilization, but it’s not like anyone would really miss, say, Greece. Later (much later), when the world starts cooling again and the ice caps start reclaiming water, you could gradually release the stored Mediterranean water and keep world sea level constant still.
* More realistic projections for the next century, however, are only in the range of tens of centimeters, making the plan I propose here less fun.