Their answers make for fascinating reading (or skimming)—the raw materials for a whole science fiction library.
This passage, for instance, reminded me of Cormac McCarthy's The Road:
Accidental nuclear war between two superpowers may or may not happen in my lifetime, but if it does, it will obviously change everything. The climate change we are currently discussing pales in comparison with nuclear winter, and the current economic turmoil is of course nothing compared to the resulting global crop failures, infrastructure collapse and mass starvation, with survivors succumbing to hungry armed gangs systematically pillaging from house to house.
And then Brian Eno (whose name I was surprised to find among all the scientists and philosophers), mentions the book explicitly in his ominous wonderings about what would happen if a general sort of pessimism took hold:
... suppose the feeling changes: that people start to anticipate the future world ... as something more closely resembling the nightmare of desperation, fear and suspicion described in Cormac McCarthy's post-cataclysm novel The Road. What happens then?
The following: Humans fragment into tighter, more selfish bands. Big institutions, because they operate on longer time-scales and require structures of social trust, don't cohere. There isn't time for them. Long term projects are abandoned — their payoffs are too remote. Global projects are abandoned — not enough trust to make them work. Resources that are already scarce will be rapidly exhausted as everybody tries to grab the last precious bits. Any kind of social or global mobility is seen as a threat and harshly resisted. Freeloaders and brigands and pirates and cheats will take control. Survivalism rules. Might will be right.
This is a dark thought, but one to keep an eye on. Feelings are more dangerous than ideas, because they aren't susceptible to rational evaluation. They grow quietly, spreading underground, and erupt suddenly, all over the place. They can take hold quickly and run out of control ('FIRE!') and by their nature tend to be self-fueling. If our world becomes gripped by this particular feeling, everything it presupposes could soon become true.
Not all the predictions are this gloomy, by the way.