There are lots of ways the world might end to be found in ancient predictions, such as the abrupt ending of the Mayan calendar on December 21st of this year. Now science has added its own warnings. These can all be found in The Coffee Table Book of Doom. Some of them are more likely than others, but there is one Doom scenario on the horizon which is certain, total, and will bring about the end of everything we know.
A solar supernova.
Astrophysicists calculate that a star like our own has a life of about ten billion years. Ours is middle-aged, about half-way there. At some point during the next five billion years, in the space of a few seconds, the core of the Sun will collapse in on itself, explode and, for a brief instant, shine at a billion times its present brightness. We won't mind, of course, because we will long since have been vaporized. We won't be aware of being sucked into the black hole the Sun leaves in its wake, and being compressed into an unimaginably small space.
Not all Doom scenarios are so far in the future. We now know of impending calamities such as the eruption of the super caldera beneath Yellowstone Park, which would bring about an endless winter and massive species extinction. Or a tsunami 50 stories high travelling at the speed of a jumbo jet which would devastate the Eastern United States. Or a new strain of influenza virus which would create a global pandemic. Or gamma and x-rays from a hyperactive sun wiping out satellites and digital communications and plunging us back into the Stone Age.
Being human, the first question is always what we can do about it. Not everyone will react in the same way. Here are some possible responses: