Humanity is at risk from a series of dangers of our own making, according to Prof Stephen Hawking.
He gave a lecture to an audience of hundreds attending the first in a series of BBC Reith Lectures, which pertain to research about black holes. That audience of hundreds has now turned into the entire world, fixated on the words that Hawking says. Especially when predictions of doom, gloom, and booms are made.
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.
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.
However, we will not establish self-sustaining colonies in space for at least the next hundred years, so we have to be very careful in this period.