Humanity's demise may be our own doing.

At the BBC's annual Reith Lectures, physicist Stephen Hawking said advances in science and technology could lead to the end of the world.

"Although the chance of a disaster to planet Earth in a given year may be quite low, it adds up over time, and becomes a near certainty in the next thousand or ten thousand years," he told the BBC. "By that time we should have spread out into space, and to other stars, so a disaster on Earth would not mean the end of the human race," Hawking says.

Here are his predictions for the nightmarish scenarios that could end the world (or at least humanity's participation in it).