I think that in any political conversation you ought to keep the material base that undergirds people's attitudes on a subject in view. Why don't westerners care more about climate change?

(Gen X and older) The major effects of climate collapse will come for their children, not themselves
Stability and comfort are threatened by the radical change necessary to shift out of the fossil economy
Alienation generally wards people against wanting to take radical actions because they do not perceive themselves to belong to a social group to which they have any responsibility of action
Imperialism as a whole benefits from wrecking the Global South

Are people actually aware of all these material conditions? Not necessarily. But the fact that they are the base on which the propaganda of the western climate movement is built has already limited what it can say. You have to navigate these points, you have to acknowledge that there are reasons for a self-interested westerner to conclude they simply do not want to be invested in an environmentalist movement because climate collapse is not a big deal to them. In a way, your scab comparison is not a great analogy, because scabs are people that would otherwise benefit from the long term gains of organized labor. As the situation stands, a significant number of ordinary people in the west have more skin in the fossil fuel game than the humanity surviving the 21st century game.