That just means you've invented a new fancy way to combat rising oceans!

(No, in reality, we have nowhere near the power to make appreciable amounts of hydrogen escape. Even if you electrolyzed water continuously with 2.5 TW of power, which is roughly global average electricity generation, you'd lose something like 4 cubic kilometers of water per year. The Earth meanwhile has over a billion cubic kilometers of water in its oceans, so you'd need over 250 million years to make them disappear.)

Only if the hydrogen is very high up. Hydrogen released at ground level will almost entirely be oxidized before it can get that high.