Odds are decent that if we ignored climate change it would cause billions of people to die and create massive disruptions in the lives of those who live over the next several centuries.

It would only be catastrophic, not existential. We should work hard to reduce the risks and mitigate the impacts, but the species will go on even if we ignore it.

And, almost everything is getting better faster than anyone predicted. There's a strong case for climate optimism, and a future that we can improve by continuing to take action and put in the hard work of fixing the world.