A challenge in making people care about techno-apocalypse is that most of the proposed technologies which could cause it exist in the future, not the present.
There’s all-out thermonuclear war, sure. If the Bush administration is dumb enough to attack Iran before he leaves office, then we could have serious problems with Russia (the country my family left when the Communists took over), whose minister of defense has cautioned the US not to lay a hand on Iran. If Putin’s successor is as gangster as he is, then Cold War part II (or Hot War part I) can’t be ruled out.
But would this kill everyone? Not too likely. Although burning cities do create black clouds which can initiate widespread crop failure, this effect is temporary. The world is a big place, and you can’t nuke it all.
So, in examining possible sources of human extinction risk, we have to look to the future. In a way this is reassuring, because we have time to prepare, but in another way it’s not, because some of the scenarios are too futuristic …