From a communicative perspective- yes, you can say this and people will understand what you mean. In terms of more ‘accurate’/natural English, I’d recommend saying ‘the earth is polluted’ instead.

The sentence means that there is some amount of pollution on earth, which seems like an obvious statement. You could add a word, such as 'much' pollution to make your likely intended meaning clearer, but Isabel's version sounds more natural.

You can certainly say that. However, it doesn't really mean much. It's like saying "there is sadness on earth". Pollution of what? Where? The earth itself is not polluted. Pollution is only found in the air, land and sea. The solid planet itself is not polluted. You can say "pollution is found everywhere" "the air, land, and sea are everywhere polluted" "the earth's environment is polluted"