Great, now the ocean levels are going to drop and kill the marine life.
This isn't happening anytime soon, even if industrial production levels are reached someday. All the water on the Earth is part of a cycle, whatever its uses, it goes back to the sea after some time, which can be a long time, sure, but it does.
The problem might be lying in the reduced salt levels in the sea. *This* could be a problem, not sea level. Melt all the pure water at the poles, and this will create a huge problem for salt water lifeforms, and consequently for humans! The amount of water will remain the same overall.