and there’s apparently nothing to be done to fix it in our lifetimes,
This really isn’t true, and treating it as true will lead to a much nastier future than “it feels really hot out most of the time”. It has implications for agriculture and ecological collapse, with entire societies being destroyed and some of the more privileged ones turning to eco-fascism. It’s a much darker future than you give it credit for, but also much less inevitable.
It’s certainly true that politicians and the owning class oppose environmental action very strongly, but that doesn’t make it hopeless. We, the working class, are the basis of their power and wealth; we concretely have the power to force them to cooperate or topple them entirely. Clearly, the enviromental movements aren’t that strong yet, but they are getting stronger and the decaying environment will provide a basis for accelerating their growth as more people like you and I begin to take these issues seriously.