What environmental reasons justify sacrifice?

I can only think of four fundamental environmental rationales off hand.  Email or leave a comment if you think of more.  

1. Global warming 
1. This really just duplicates the following reasons, but is potentially so important that it deserves its own category.
2. Reduce resource extraction to preserve nonrenewables for future generations? 
3. Reduce toxic pollution (poisons by ingestion or breathing)? 
4. Wellbeing of other species?