I have a question and am hoping you may have some comments: What happens to Earth when all beings reach Nirvana? If all beings progress to enlightenment, then they won’t be coming back, right? If so, then the Earth dies… everything from us to krill would be gone, at least physically. I don’t see that this would be a good thing, since to me, the world is a magnificent phenomenon -irrespective of our human experience of living on it. I love this Earth and feel lucky to have experienced its natural beauty. I wonder about this. Would it be possible to be enlightened and live on Earth too? It is a real sticking point for me. Any comments would be GREATLY appreciated.
If you take it that Nirvana means that you exit the cycle of samsara, then that happens after death. A Bodhisattva is an enlightened person who is willing to skip that and stick around on Earth to help others reach enlightenment. Theoretically, eventually, someday every being will reach enlightenment and it would indeed be time for all creatures to move on.
To us here, now, the Earth is a beautiful thing that must be protected for future generations, I believe. However, attachments are something that we will give up after attaining Enlightenment, and that includes being attached to the world. No matter how beautiful it may be, an enlightened person would be willing to let it go if that meant that all suffering would be ended.
You ask, “Would it be possible to live on Earth and be Enlightened too?” Technically, yes, if you return as a Bodhisattva, then you can stay behind, at least until that far-off future when everyone has reached Nirvana. However, it could also be that such a strong attachment to the Earth might keep you from getting there in the first place.
Attachments and irrational grasping/desire are what causes suffering. Attachments, even to things that are otherwise good and wonderful, are still attachments, and will cause suffering eventually.