I think the main message of this film was for humans to stop trashing our own back yards. The planet won't survive, and neither will we if we ignore it! Most of us would agree "well, total tree destruction won't happen overnight". And there it is. Like slowly rising temperature spread over decades, there's no hurry, we don't notice it, then bam! - there are no trees.
The look of the city in 50 years from now was a bleak but interesting aesthetic. And beautiful natural scenery after the time travel.
This film's time travel was an interesting layer, which had to be there to demonstrate the question "are we in control of our fate?"
Performances were great to watch.