I think that's where everyone stands still. The word might is an assumption. Assumptions should never lead to policy making. We use to have a system where everyone who owned land had to respect their neighbor's land by not polluting. That includes via air or water. So, it has a balance. However, when government owns land, they have no desire to take care of it properly. Land should be in the hands of the people because people generally care about their own possessions.
But on the other hand, you should never make political decisions on the assumption that everything will be alright. That by itself is an assumption. Might is not an assumption, it is a "What-if". Assuming it WON'T happen is an assumption.
Really, do pros and cons.
1)If we try to prevent it, and it doesn't happen, it would lead to lower economy, and possibly depression etc.
2) If we try to prevent it, and it does happen, we will have lower economy, but it might not be as bad as it otherwise would.
3) If we don't prepare and it don't happen, everyone will be happy and economy will be good
4) If we don't prepare and it does happen, not only will our economy be worse, it could possibly lead to the worst economy we've ever had. Not only would people get poorer, it could lead to a lot of people dieing because of lack of food, people would become homeless, etc.
Really, would you rather the politicians don't take actions trying to prevent it from happening, rather then sit and wait in case it does NOT happen? That by itself is somewhat contradicting by you, as I assume your post was centered in the "Don't take action" camp.
And its not really about the government taking care of their land. Its about the politicians caring about its citizens well-being and future, and the earth which, believe it or not, is their home, and will always be unless they somehow manage to find a way for interstellar transportation and can move to their own little planet, in which case that will be their now home.
THEN they have all the right they want to say "Screw the earth". But until then, they should care about the earth, as it is their children, grand children etc. that will be affected by it, not them themselves. Is it really that smart to put it off for the other generation to take care of, when it might be too late by then? That's like taking a really huge fucking dump right in their grand children's face.