No, the least effective would be looking for the silver bullet. Because if there is strong economic, business incentive to change nothing, nothing changes. Yes, gas getting more expensive motivates many individuals to seek more fuel-efficient cars and reducing unnecessary driving, carpool/ share rides, etc. There are many things besides a new, more efficient vehicle, and the used car such a person buys in 10 years is more efficient than their current car because of those new cars today. That's how it works, nothing works instantly. A person who understands climate change and expects to either be around or have descendants around would want the effects of climate change to be minimized. An underground shelter will not save them, and would be a lot more expensive than any of the things you said most can't afford. But don't take my word for it, you can just watch the next few decades unfold. We're locked in for serious pain. The question is how much worse we want to make it, not if it can be avoided, at this point.