The ocean is absolutely carbonated. What do you think fish are made of?
Also, there is shitload of bicarbonate ion in the ocean.

That is not accurate. The earth is 0.02 % water. Oh and that makes at least one stupid alien invasion movie even more stupid.
You mean the one where water is toxic for the aliens?
Wouldn’t that 0.02% make it more likely they visited earth without realising the surface is covered in water?
You know, ignoring the fact that hydrogen and oxygen are some of the most common elements in the universe and water is the most common molecule.
There is at least one where they come here to take our water (Oblivion, otherwise an OK movie). The “water is toxic movie” (signs?) is, of course, somehow even more stupid. Man that movie was crap all around.




