Explanation:

The sentence "If we do nothing to curb this pollution, I guarantee we will face the wall in the future" needs a phrase that conveys dealing with consequences. Let's evaluate the options:

- Face the wind: Usually implies facing challenges. Not quite fitting for consequences.

- Face the music: ?? This means to confront repercussions or deal with the consequences. It fits perfectly in this context.

- Face the dark: Suggests dealing with the unknown or fear. Not directly about consequences.

- Face the stick: Not a common phrase, and it does not convey dealing with consequences.

Answer: Face the music is the correct substitute.