The demise of civilization has been predicted since it began, but the odds of keeping Planet Earth alive and well are getting worse amid a breakneck pace of scientific advances, according to Martin Rees, Britain's honorary astronomer royal. Rees' predictions were discussed in a June 9 Reuters story.

Rees calculates that the odds of an apocalyptic disaster striking Earth have risen to about 50 percent from 20 percent a hundred years ago. The 60-year-old scientist, author of the recently published Our Final Hour, says science is advancing in a far more unpredictable and potentially dangerous pattern than ever before. He lists as mankind's biggest threats: nuclear terrorism, deadly engineered viruses, rogue machines and genetic engineering that could alter human character. All of those could result from innocent error or the action of a single malevolent individual.

By 2020, an instance of bioterror or bioerror will have killed a million people, Rees contends. "There is a growing gap between doors that are open and doors that should be open," Rees, a professor at Britain's Cambridge University, said in a recent interview.

The cosmologist concedes that natural disasters have always loomed -- so-called supervolanoes could explode at any time and asteroids could slam into the planet, causing massive climate changes -- but says the most frightening risks are probably man-made.