If Australia and the USA both came to their senses then climate action would very much happen.
China could also take the lead here; it's actually surprising that they aren't because it's an ideal opportunity for them to project power on a global scale and an important step in their replacing the USA as the global super power.
Climate action does not project power or offer an economic return. It's pretty much guaranteed to be the opposite - forgoing an opportunity or building things at your expense in order to not disadvantage the rest of the world.
That's not guaranteed to be true. Leading the way on fostering new cleantech is a way to get ahead of the same cleantech industries elsewhere. The question is really how good can the timing be rather than if it's going to happen.
China could also take the lead here; it's actually surprising that they aren't because it's an ideal opportunity for them to project power on a global scale and an important step in their replacing the USA as the global super power.