To move such immense amounts of water, you need energy. A lot of it. For that energy to be available, you will likely be creating carbon dioxide. This raising

To move such immense amounts of water, you need energy. A lot of it. For that energy to be available, you will likely be creating carbon dioxide. This raising the levels further. This requiring more energy. It's kinda like the rocket fuel equation, except the end result is throwing some of the most precious resource we have into space. If an energy hungry solution is what you are after, you'll be far better off raising the landmasses at risk than trying to siphon the oceans.