No doubt there might be warming, the cause however is unknown. Man is arrogant to think the climate is stable, never has been, never will be.
We should be good stewards to the earth (in other words, dont be a polluting scumbag.)
The biggest problem I have with Al proclaiming the earth is warming, the earth is warming is this- he personally benefits from it. Where does he buy his carbon credits from (which are just a whole socialistic scam anyways?) His own company! Scumbag. If you believe the sky is falling, you take steps to prevent it, not just expect others to heed your warnings and do it for you while you sit in your mansion. If he REALLY believed it- he wouldn't fly around in private airplanes, big ol SUVs especially when he could do live 'shows' via the internet and use much fewer resources spreading his message.
I just went to arizona near lake powell. You could see the pollution from a singe power plant from miles (MANY MANY miles) away. That could be eliminated for about 3 million bucks/year. They choose not to do it. Before you say 3 mil is a lot of money- think of the cost of coal (it burns about 8 million tons of coal/yr).. 3 mil is nothing.
There is a finding of no significant impact for the plant- all you have to do is go out west to see the significant impact of dirty power (not all coal is dirty, and the coal that is can be cleaned up). That is where the stewardship comes in. Clean up your crap.