All your other suggestions are fine, we can use more energy, more arable land, more cooling evaporation (in case global warming is real), etc. The only problem is suggesting that this flooding will have any impact on sea levels WRT Greenland's ice. I prefer to point to the fact that the melt from Greenland is trivial and there's no reason to believe it will rise unless one is to believe certain climate models which are not driven by physics and cannot be verified.
Further, evaporation rates are only a small part of the function on how sea and lake levels will rise and fall. There are vast stretches of low and even below sea level areas in west central Asia (especially around the Caspian Sea) where shorelines are receding, not increasing.
Some of this is, indeed, even man made, particularly the overuse of water resources from the Soviet era. A diversion of even salty sea water to these areas would assist in an ecological recovery, even without regard to global warming.
The Qattara Depression example was cited specifically because it would be a relatively low cost engineering project. A diversion project from, say, the Black Sea to the Caspian Sea would be possible but much more complicated and expensive, but still cheap compared to the type of economic dismantling the global warming alarmists are talking about.
The fact that they won't even discuss ocean diversion projects as part of the solution gives you a clue as to just how phony and invented this problem really is. They are fixated on Marxist and top-down economic solutions only.
However, Marxism is just as much an ecological catastrophe as it is a human and economic catastrophe wherever it had been tried. That's my main point.