The Doomsday Clock is a symbolic clock face, maintained since 1947 by the board of directors of the Bulletin of the Atomic Scientists at the University of Chicago. The clock was initially set to seven minutes to midnight (11:53pm) and has been adjusted 27 times since its inception. The closer the clock is to midnight, the closer the world is estimated to be to global disaster. The most recent officially-announced setting — five minutes to midnight (11:55pm) — was made on January 10, 2012.
Originally, the clock represented the threat of global nuclear war. Since 2007 it has also reflected climate-changing technologies and “new developments in the life sciences that could cause global harm.”
In 1953, the clock’s closest approach to midnight since its inception was set at 11:58 when the United States and the Soviet Union tested thermonuclear devices within nine months of each other. (wiki)