Was there excessive polution on Earth?
I know that the advertisements mentioned pollution, but the I don't recall the movie saying the Earth was polluted. I recently re-watched this film on Netflix, and it is mentioned that the entire Earth has a constant temperature of 75-degrees, so no runway climate change there like Soylent Green. They also mention there is not poverty, no disease, and everyone has a job.
So the forests on Earth don't appear to have been destroyed by pollution. Rather, something else must have displaced them. And the Earth seems livable and comfortable despite this.