At least 1.5 billion years after it last saw the surface, flowing liquid may host life.

If Hollywood’s right, the apocalypse will be brutal. Aliens, nuclear war, zombies, plague, enslavement by supersmart robots — none of them are good endings. Some archaeologists, however, believe an apocalypse has already come and gone. About 75,000 years ago, they say, a monster volcanic eruption nearly wiped out humankind, leaving behind only a few thousand people to repopulate the world. The explosion of Indonesia’s Toba volcano was the largest eruption of the last 2 million years. The volcano coughed up some 2,000 to 3,000 cubic kilometers of ash, enough to fill almost three-quar...

Chance more than doubled that capital city will soon experience big temblor, researchers calculate. (p. 20)

At 400 parts per million, greenhouse gas concentration is now higher than it has been for millions of years. (p. 20)