[hinkley]

If global warming continues to raise sea level, it could well become the case that such a project is undertaken but with the goal of keeping the Mediterranean roughly where it is, which would simplify changes necessary elsewhere to keep the Black Sea a sea and keep harbors navigable.

Lowering the Mediterranean a few feet and running turbines at a flow rate to counteract evaporation might work, especially since evaporation and power usage track somewhat. Hot days evaporate more water, and require more air conditioning. The volume of the reservoir would allow quite a bit of buffer if you wanted to time shift some of that usage, aiming for monthly or quarterly averages instead of daily.