It will probably increase the concentration of water vapor in the atmosphere, which will lead to further warming as water vapor absorbs the heat radiated by Earth.

Don’t forget that oxygen is useful for breathing too. Semi-important, I hear.

ChatGPT estimates that if we converted all of earth’s atmospheric oxygen into water (via burning with hydrogen), ocean levels would rise about 3.7 meters: https://chat.openai.com/share/c9c8ce51-6070-49b6-a092-86e4a4...

I don’t have time to check this math, so take it with a substantial grain of salt.