If the richest and most powerful countries say "there is no climate change" and "others want to destroy our economy", then the answer is a pessimistic one. The same applies to countries that say "yes, there is a climate change and we must do something", but in the end avoid doing anything to unwind the death spiral.
> Most rich countries acknowledge climate change and try to come up with solutions. The big outlier is the US.
You could generalise that to:-
Most rich countries acknowledge <foo is a problem> and try to come up with solutions. The big outlier is the US.
Where <foo> is healthcare, corporate governance, lobbying, women's rights, racism, income equality, prison incarceration rates, police brutality.
Growing up in the UK in the 80's I was fascinated by America and planned on one day visiting if not living there.
Now? If I leave the UK (and I probably will) it'll likely be Germany or Holland, they aren't perfect (what is?) but they look a lot better than the US/UK these days.
The problem is: if you remove yourself, it's still going on back home. It's probably better to stay where you have some power to try to change it for everyone's good, particularly when foo is something like climate that affects the whole world. (or that's what I tell myself when Canada beckons)
Maybe but then on the flip side in my country we've had a decade of things getting progressively worse up to and including the massively pointless, expensive and dangerous Brexit.
I'm pretty tired of it to be honest, I don't recognise this country any more.