The Doomsday Clock has been maintained by members of the Bulletin of the Atomic Scientists since 1947. The Clock is a metaphor for the threats humanity faces from unchecked scientific and technological advances. Midnight represents a hypothetical global catastrophe, and the Bulletin’s opinion on how close the world is to such a catastrophe is represented by the number of minutes until midnight. The global status is assessed in January of each year, and the minute hand is set accordingly. The main factors currently influencing the Clock are nuclear risk and global warming. The Bulletin‘s Science and Security Board also monitors new developments in the life sciences and technology that could inflict irrevocable harm to humanity.