The EPA has at no point in history had the abilty to "fight climate change". It is just no longer going to be allowed to even pretend to try. In theory, if the current government of the US were immediately overthrown in a violent revolution, and a new green socialist government was built in its ruins, and then that government conquered the world, and imposed harsh austerity measures on the survivors of the Final World War, it could begin to actually fight climate change.

Back to the real world though- the mass extinction is well underway, all future tipping points will be blown past on the way to a new hothouse Earth era. It is happening faster than any previous mass extinction so will probably be right up there with the worst of them. The only real variable at play is that the longer it takes for humans to either go extinct or permanently collapse back to the stone age, the higher percentage of Earth's biodiversity will be wiped out with us.

But yeah, sure. If we vote the Democrats back in '28, we can totally go back to setting targets and guidelines and publishing reports on things and Taking Climate Change Very Seriously. As long as it doesn't inconvenience the donor class too much, of course.

Rules made by humans are entirely able to be changed by humans.

Nothing this administration does is technically irreversible. It just depends on how far you are willing to go to reverse it.