It seems, that no one really knows what is going to happen.
Global Warming verses a Ice Age
Hey how about another Comet strike
Or a major volcanic eruption that could spread enough ash in the air to chill the planet causing a major extinction.
The Comet and Volcano are more likely than the technological induced weather change.
What created more destruction, Mt. St. Helens or the technology of the entire west coast for the last 20 years, oh what the heck, last 100 years. Perhaps you should ask those people from Pompeii.
This does not even take in to account the hurricanes or tornados that are regular destructors.
I say lets tame nature, itís the real destructive force around here,
Letís just evolve to a space going people and leave this Big Blue Marble to itís own devices and anyone that wants to stay without the benefits of technology can remain behind.
I'm sure Mom Earth can purge all traces of us in a few hundred year, perhaps a thousand.
Just my rant