Here's my take:
End of the world scenarios generate good ratings, so the TV channels will flood us with them until public interest wanes.
Most of these ideas like global warming are junk science made up by crackpots, taking little pieces of a big picture from here and there and trying to capitalize on them.
I have to laugh at these scenarios. "What happens when da grid goes down and we gots no moe intewebz??" Know what happens? We look like the rest of the world. Yeah, I'm sure you heard it: if you own more than one set of clothes, drive a car, have your own home, etc., you're in the top 5% richest people in the world. The numbers change, but the concept stays the same.
In the early to mid 1900s, the majority of Americans were either involved in commercial farming to one degree or another, or at least grew some of their own food. We'd go back to that. Somalia and other african crapholes do not reflect what would happen here. People too stupid and lazy to do anything but slaughter each other when they aren't busy getting messed up on khaat, is not the demographic we have. The fall of a first world nation looks like it did when Eastern Europe fell. There will be a short time of very bloody conflict, and people will adapt to a new, lower lifestyle and move on.
Bottom line: the "end of the world" for us, looks like a normal day to most of the world.
Now, if you want to talk about a real end of the world scenario like a supervolcano explosion, massive asteroid strike, pandemic, global thermonuclear war, etc. Why worry about it? There isn't a damn thing you can do about it. Roll the dice, and if you make it, then you can stand around with the other survivors and be surprised that you lived.
Me? I'm going to get my ducks in a row for the surgery I have tomorrow, which requires a first world nation's operational power grid and high-tech society to accomplish, and getting a stack of books and DVDs together for lounging around the house for the next couple of weeks while I recover in the A/C.
Enjoy your life and don't worry about the things you can't control.