Originally, the Clock, which hangs on a wall in a Bulletin's office in the University of Chicago, represented an analogy for the threat of global nuclear war; however, since 2007 it has also reflected climate change and new developments in the life sciences and technology that could inflict irrevocable harm to humanity.
The most recent officially announced setting?three minutes to midnight (11:57 pm)?was made on January 22, 2015.
Doomsday Clock moves two minutes closer to midnight - CBS News