When I was growing up the big three threats (not counting cold-war nuclear annihilation) were:
1) Pollution (remember the Chief Iron Eyes Cody Keep America Beautiful PSA)
2) Overpopulation (and the associated resource depletion -- it requires a lot of raw material to keep pollution at #1) and
3) An imminent and overdue Ice Age (which I guess might solve the other two with a heavy winter kill, resulting in fewer people to pollute -- of course, civilization would also end but that's just the price you pay for a cleaner world).

I'm not able to say that there's no such thing as Global Warming, but I am suspicious of the Neo-Luddites that tend to be at the forefront of that issue. They often seem hypocritical when flying on private jets to meet and say that the rest of us should be riding bicycles and public transit, whether it exists or not.

Most industry is much cleaner than when I was growing up, but still they want to close it down -- if people don't work, how are they going to live.

They want to stop people from encroaching on the environment, but do they have a plan for what to do with the people? Maybe when they get issued their bike, they'll also be allocated a fixed square footage of living space in the collectives that'll replace those evil "factory farms". Hey, people are animals too!!

Pardon my rant, but while I admit that I don't know the answers, I also believe that the "government should regulate people's actions rather than safeguard their freedoms" crowd (like Gore) have been trying to scare people into believing that the world is ending when I just don't believe that's the case. I expect that soon enough, some other doomsday scenario will replace Global Warming, who knows, maybe it'll be zombies.