Even though we, collectively, are driving said train. As a believer in the great filter theory[1] it's a shame given how far we've apparently come, only to be brought low by our desires, our inability to believe we could screw ourselves this royally, and our collective lack of give-a-shit to fix it.

[1] https://en.wikipedia.org/wiki/Great_Filter

climate change isn't an one/off effect but gradual

every bit of improvement is a higher chance to avoid some of the most catastrophic outcomes (where the unlikely but possible worst outcome being a mass extinction chain reaction which humanity will find very very hard to survive in a functioning manner/without losing their future)

so still worth fighting for any improvement even if we can't avoid a catastrophe anymore, as there is a huge margin between what we still can archive, and what we might end up with if we stop fighting and are quite unlucky