First off, he is alive or dead? All we've had for maybe three years are audio tapes. This video from 2007, here analyzed in Radio Free Europe Afghanistan, looks a little odd to me.
The beard looks fake and since when does he dye his hair? Every other video has him almost completely gray headed. In 2001, Time reported the use of at least 10 doubles.
His voice? Voices are not that hard to fake, ask Rich Little!
It would be to the advantage of al Qaida to keep the idea of Bin Laden alive, for propaganda but more importantly, OBL had access to hundreds of millions of dollars of his own, not to mention the donations they collect every year. Even hiding out in caves costs money. Arms, food for your "soldiers", explosives for your human weapons including air flight, etc.
As far as the global warming angle? Please. This is just an attempt to wrangle in more hatred for America. Don't know how that's possible, the world hates us, period.
So. Do you think he is alive or dead? Have any proof? I'd love to hear it.