Does nature and beauty matter if there are no sentient beings to observe it?
When many (most?) people talk about mitigating or reversing climate change, their main goal is the benefit to humanity. Sure, there is some level of empathy and caring for the species going extinct every year, but even part of that is only as far as how a healthy, diverse biosphere better supports human life.
Global civilization has a long history of emptying pristine environments of sentient beings and not realizing what it has done...we have no monopoly on sentience or beauty. We are just a small part of nature.
