I saw part of a special on the History channel this weekend but couldn't watch the entire program at the time. The focus of the show was the six greatest threats to human life on the planet.
First was the possibility of nuclear holocaust, potentially problematic as the number of governments around the world, not all particularly stable, with nuclear weapons technology increases.
Second was biological, the potential for a global pandemic that could spread widely before it was even recognized, let alone before treatments could be developed. The greater concern there was not a spontaneously occurring pandemic but the more effective microbiological infectious agents that potentially could be developed as weapons.
Global climate change was third. I didn't see the whole segment, unfortunately, but most of it fit with things I already know to some extent. Droughts, flooding, and changes in storm activity and severity were among those occurrences covered. I had to leave the program at this point.
I recommend the program to anyone who may be interested in this. It was well presented, as are most programs on the HC, and did attempt to address both pros and cons of each position. I'll definitely try to see it when it's re-run. Had to get up at 5 a.m. on Sunday to attend a seminar so I missed the remainder of the show.