I'm surprised they didn't mention Super volcanoes:
http://www.bbc.co.uk/science/horizon/1999/supervolcanoes.shtml
As for global warming, I really don't think it is an E.L.E. - many may die or be displaced but on the whole mankind will adapt. It also isn't in a viruse's best interests to eradicate ALL its potential hosts.
I think the only extinction level events would come about from a severe 'nuclear winter' caused by super volcanoes, asteroid impacts or our own weapons. Imagine what the world would be like after a night that lasted three years!